THE HIERARCHY OF NUTRITION EVIDENCE AND
HOW TO INTERPRET THEM
Introduction
1.9: Types of Research Studies and How To Interpret Them
The field of nutrition is dynamic, and our understanding and practices are always evolving.
Nutrition scientists are continuously conducting new research and publishing their findings in
peer-reviewed journals. This adds to scientific knowledge, but it’s also of great interest to the
public, so nutrition research often shows up in the news and other media sources. You might be
interested in nutrition research to inform your own eating habits, or if you work in a health
profession, so that you can give evidence-based advice to others. Making sense of science
requires that you understand the types of research studies used and their limitations.
The Hierarchy of Nutrition Evidence
Researchers use many different types of study designs depending on the question they are
trying to answer, as well as factors such as time, funding, and ethical considerations. The study
design affects how we interpret the results and the strength of the evidence as it relates to
real-life nutrition decisions. It can be helpful to think about the types of studies within a
pyramid representing a hierarchy of evidence, where the studies at the bottom of the pyramid
usually give us the weakest evidence with the least relevance to real-life nutrition decisions, and
the studies at the top offer the strongest evidence, with the most relevance to real-life nutrition
decisions.
Figure 2.3. The hierarchy of evidence shows types of research studies relative to their strength
of evidence and relevance to real-life nutrition decisions, with the strongest studies at the top
and the weakest at the bottom.
The pyramid also represents a few other general ideas. There tend to be more studies
published using the methods at the bottom of the pyramid, because they require less time,
money, and other resources. When researchers want to test a new hypothesis, they often start
with the study designs at the bottom of the pyramid, such as in vitro, animal, or observational
studies. Intervention studies are more expensive and resource-intensive, so there are fewer of
these types of studies conducted. But they also give us higher quality evidence, so they’re an
important next step if observational and non-human studies have shown promising results.
Meta-analyses and systematic reviews combine the results of many studies already conducted,
so they help researchers summarize scientific knowledge on a topic.
Non-Human Studies: In Vitro & Animal Studies
The simplest form of nutrition research is an in vitro study. In vitro means “within glass,”
(although plastic is used more commonly today) and these experiments are conducted within
flasks, dishes, plates, and test tubes. These studies are performed on isolated cells or tissue
samples, so they’re less expensive and time-intensive than animal or human studies. In vitro
studies are vital for zooming in on biological mechanisms, to see how things work at the cellular
or molecular level. However, these studies shouldn’t be used to draw conclusions about how
things work in humans (or even animals), because we can’t assume that the results will apply
to a whole, living organism.
1.9.1 49296
Animal studies are one form of in vivo research, which translates to “within the living.” Rats and
mice are the most common animals used in nutrition research. Animals are often used in
research that would be unethical to conduct in humans. Another advantage of animal dietary
studies is that researchers can control exactly what the animals eat. In human studies,
researchers can tell subjects what to eat and even provide them with the food, but they may
not stick to the planned diet. People are also not very good at estimating, recording, or
reporting what they eat and in what quantities. In addition, animal studies typically do not cost
as much as human studies.
There are some important limitations of animal research. First, an animal’s metabolism and
physiology are different from humans. Plus, animal models of disease (cancer, cardiovascular
disease, etc.), although similar, are different from human diseases. Animal research is
considered preliminary, and while it can be very important to the process of building scientific
understanding and informing the types of studies that should be conducted in humans, animal
studies shouldn’t be considered relevant to real-life decisions about how people eat.
Observational Studies
Observational studies in human nutrition collect information on people’s dietary patterns or
nutrient intake and look for associations with health outcomes. Observational studies do not
give participants a treatment or intervention; instead, they look at what they’re already doing
and see how it relates to their health. These types of study designs can only identify
correlations (relationships) between nutrition and health; they can’t show that one factor causes
another. (For that, we need intervention studies, which we’ll discuss in a moment.)
Observational studies that describe factors correlated with human health are also called
epidemiological studies.1
One example of a nutrition hypothesis that has been investigated using observational studies is
that eating a Mediterranean diet reduces the risk of developing cardiovascular disease. (A
Mediterranean diet focuses on whole grains, fruits and vegetables, beans and other legumes,
nuts, olive oil, herbs, and spices. It includes small amounts of animal protein (mostly fish),
dairy, and red wine.2) There are three main types of observational studies, all of which could
be used to test hypotheses about the Mediterranean diet:
Cohort studies follow a group of people (a cohort) over time, measuring factors such as diet
and health outcomes. A cohort study of the Mediterranean diet would ask a group of people to
describe their diet, and then researchers would track them over time to see if those eating a
Mediterranean diet had a lower incidence of cardiovascular disease.
Case-control studies compare a group of cases and controls, looking for differences between
the two groups that might explain their different health outcomes. For example, researchers
might compare a group of people with cardiovascular disease with a group of healthy controls
to see whether there were more controls or cases that followed a Mediterranean diet. Cross-
sectional studies collect information about a population of people at one point in time. For
example, a cross-sectional study might compare the dietary patterns of people from different
countries to see if diet correlates with the prevalence of cardiovascular disease in the different
countries.
Prospective cohort studies, which enroll a cohort and follow them into the future, are usually
considered the strongest type of observational study design. Retrospective studies look at what
happened in the past, and they’re considered weaker because they rely on people’s memory of
what they ate or how they felt in the past. There are several well-known examples of
prospective cohort studies that have described important correlations between diet and disease:
1.9.2 49296 Framingham Heart Study: Beginning in 1948, this study has followed the
residents of Framingham, Massachusetts to identify risk factors for heart disease.
Health Professionals Follow-Up Study: This study started in 1986 and enrolled 51,529 male
health professionals (dentists, pharmacists, optometrists, osteopathic physicians, podiatrists,
and veterinarians), who complete diet questionnaires every 2 years.
Nurses Health Studies: Beginning in 1976, these studies have enrolled three large cohorts of
nurses with a total of 280,000 participants. Participants have completed detailed questionnaires
about diet, other lifestyle factors (smoking and exercise, for example), and health outcomes.
Observational studies have the advantage of allowing researchers to study large groups of
people in the real world, looking at the frequency and pattern of health outcomes and
identifying factors that correlate with them. But even very large observational studies may not
apply to the population as a whole. For example, the Health Professionals Follow-Up Study and
the Nurses Health Studies include people with above-average knowledge of health. In many
ways, this makes them ideal study subjects, because they may be more motivated to be part of
the study and to fill out detailed questionnaires for years. However, the findings of these
studies may not apply to people with less baseline knowledge of health.
We’ve already mentioned another important limitation of observational studies—that they can
only determine correlation, not causation. A prospective cohort study that finds that people
eating a Mediterranean diet have a lower incidence of heart disease can only show that the
Mediterranean diet is correlated with lowered risk of heart disease. It can’t show that the
Mediterranean diet directly prevents heart disease. Why? There are a huge number of factors
that determine health outcomes such as heart disease, and other factors might explain a
correlation found in an observational study. For example, people who eat a Mediterranean diet
might also be the same kind of people who exercise more, sleep more, have higher income (fish
and nuts can be expensive!), or be less stressed. These are called confounding factors; they’re
factors that can affect the outcome in question (i.e., heart disease) and also vary with the
factor being studied (i.e., Mediterranean diet).
Intervention Studies
Intervention studies, also sometimes called experimental studies or clinical trials, include some
type of treatment or change imposed by the researcher. Examples of interventions in nutrition
research include asking participants to change their diet, take a supplement, or change the time
of day that they eat. Unlike observational studies, intervention studies can provide evidence of
cause and effect, so they are higher in the hierarchy of evidence pyramid.
The gold standard for intervention studies is the randomized controlled trial (RCT). In an RCT,
study subjects are recruited to participate in the study. They are then randomly assigned into
one of at least two groups, one of which is a control group (this is what makes the study
controlled). In an RCT to study the effects of the Mediterranean diet on cardiovascular disease
development, researchers might ask the control group to follow a low-fat diet (typically
recommended for heart disease prevention) and the intervention group to eat a Mediterrean
diet. The study would continue for a defined period of time (usually years to study an outcome
like heart disease), at which point the researchers would analyze their data to see if more
people in the control or Mediterranean diet had heart attacks or strokes. Because the treatment
and control groups were randomly assigned, they should be alike in every other way except for
diet, so differences in heart disease could be attributed to the diet. This eliminates the problem
of confounding factors found in observational research, and it’s why RCTs can provide evidence
of causation, not just correlation.
Imagine for a moment what would happen if the two groups weren’t randomly assigned. What
if the researchers let study participants choose which diet they’d like to adopt for the study?
They might, for whatever reason, end up with more overweight people who smoke and have
high blood pressure in the low-fat diet group, and more people who exercised regularly and had
already been eating lots of olive oil and nuts for years in the Mediterranean diet group. If they
found that the Mediterranean diet group had fewer heart attacks by the end of the study, they
would have no way of knowing if this was because of the diet or because of the underlying
differences in the groups. In other words, without randomization, their results would be
compromised by confounding factors, with many of the same limitations as observational
studies.
In an RCT of a supplement, the control group would receive a placebo—a “fake” treatment that
contains no active ingredients, such as a sugar pill. The use of a placebo is necessary in medical
research because of a phenomenon known as the placebo effect. The placebo effect results in a
beneficial effect because of a subject’s belief in the treatment, even though there is no
treatment actually being administered.
1.9.3 49296
An example of the placebo effect
Blinding is a technique to prevent bias in intervention studies. In a study without blinding, the
subject and the researchers both know what treatment the subject is receiving. This can lead to
bias if the subject or researcher have expectations about the treatment working, so these types
of trials are used less frequently. It’s best if a study is double-blind, meaning that neither the
researcher nor the subject know what treatment the subject is receiving. It’s relatively simple to
double-blind a study where subjects are receiving a placebo or treatment pill, because they
could be formulated to look and taste the same. In a single-blind study, either the researcher or
the subject knows what treatment they’re receiving, but not both. Studies of diets—such as the
Mediterranean diet example—often can’t be double-blinded because the study subjects know
whether or not they’re eating a lot of olive oil and nuts. However, the researchers who are
checking participants’ blood pressure or evaluating their medical records could be blinded to
their treatment group, reducing the chance of bias.
Like all studies, RCTs and other intervention studies do have some limitations. They can be
difficult to carry on for long periods of time and require that participants remain compliant with
the intervention. They’re also costly and often have smaller sample sizes. Furthermore, it is
unethical to study certain interventions. (An example of an unethical intervention would be to
advise one group of pregnant mothers to drink alcohol to determine its effects on pregnancy
outcomes, because we know that alcohol consumption during pregnancy damages the
developing fetus.)
Not all scienti c studies are created equ…
VIDEO: “Not all scientific studies are created equal” by David H. Schwartz, YouTube (April 28,
2014), 4:26.
Meta-Analyses and Systematic Reviews
At the top of the hierarchy of evidence pyramid are systematic reviews and meta-analyses. You
can think of these as “studies of studies.” They attempt to combine all of the relevant studies
that have been conducted on a research question and summarize their overall conclusions.
Researchers conducting a systematic review formulate a research question and then
systematically and independently identify, select, evaluate, and synthesize all high-quality
evidence that relates to the research question. Since systematic reviews combine the results of
many studies, they help researchers produce more reliable findings. A meta-analysis is a type of
systematic review that goes one step further, combining the data from multiple studies and
using statistics to summarize it, as if creating a mega-study from many smaller studies.4
However, even systematic reviews and meta-analyses aren’t the final word on scientific
questions. For one thing, they’re only as good as the studies that they include. The Cochrane
Collaboration is an international consortium of researchers who conduct
1.9.4 49296 systematic reviews in order to inform evidence-based healthcare, including
nutrition, and their reviews are among the most well-regarded and rigorous in science. For the
most recent Cochrane review of the Mediterranean diet and cardiovascular disease, two authors
independently reviewed studies published on this question. Based on their inclusion criteria, 30
RCTs with a total of 12,461 participants were included in the final analysis. However, after
evaluating and combining the data, the authors concluded that “despite the large number of
included trials, there is still uncertainty regarding the effects of a Mediterranean‐style diet on
cardiovascular disease occurrence and risk factors in people both with and without
cardiovascular disease already.” Part of the reason for this uncertainty is that different trials
found different results, and the quality of the studies was low to moderate. Some had problems
with their randomization procedures, for example, and others were judged to have unreliable
data. That doesn’t make them useless, but it adds to the uncertainty about this question, and
uncertainty pushes the field forward towards more and better studies. The Cochrane review
authors noted that they found seven ongoing trials of the Mediterranean diet, so we can hope
that they’ll add more clarity to this question in the future.5
Science is an ongoing process. It’s often a slow process, and it contains a lot of uncertainty, but
it’s our best method of building knowledge of how the world and human life works. Many
different types of studies can contribute to scientific knowledge. None are perfect—all have
limitations—and a single study is never the final word on a scientific question. Part of what
advances science is that researchers are constantly checking each other’s work, asking how it
can be improved and what new questions it raises.
2.3: Types of Research Studies and How To Interpret Them by Alice Callahan, Heather Leonard,
& Tamberly Powell is licensed CC BY-NC-SA 4.0.
1.9.5 49296 1.10: Healthy Skepticism in Nutrition Science
By this point in the unit, you should understand the types of studies used in nutrition research
and the quality of evidence each can provide. As you sift through studies, there are a few
limitations of nutrition research that are always worth keeping in mind:
Challenges in nutrition research: There are some inherent challenges to researching what
people eat and how it affects their health. This fact limits the quality of evidence and stirs
controversy in nutrition research.
Influence of food industry funding: Because government funding for nutrition research is
limited, much of it is funded by the food industry. Industry’s primary goal is to sell more of their
products, so they have a conflict of interest that can result in bias in the way they design
studies and interpret the results.
Being alert to these two things means always examining nutrition research with a healthy sense
of skepticism. Let’s take a closer look at these two issues in nutrition science.
Challenges in Nutrition Research
How does the food we eat affect our health? This question is exceedingly difficult to answer
with certainty. We all need to eat every day, but we can choose from a huge array of possible
foods in different combinations. And it’s probably not what we eat on any given day that
matters, but what we eat over months and years and decades—our long-term eating patterns—
that matter to our long-term health.
Imagine that you’re a nutrition researcher, and you’ve made the observation that over the last
50 years in the U.S., people have been consuming more and more processed foods (foods
made with refined ingredients and industrial processes, usually with the addition of sugar, fat,
and/or salt). You hypothesize that processed foods are contributing to obesity, which has also
increased over the last 50 years. You might first test your hypothesis in animal studies by
feeding mice and rats a buffet of potato chips, soda, and Twinkies, and measuring changes in
their body weight. You might find that the animals do, in fact, gain weight on this diet.
However, you know that what is true in rodents isn’t always true in humans, and you’ll need to
study humans in order to understand the role of processed foods in the obesity epidemic.
Your next step might be to conduct an observational study, the most common type of study
design in human nutrition research. For example, you might do a cross-sectional study where
you compare groups of people who eat a lot of processed foods with those who eat very little.
Or you might conduct a prospective cohort study in which you ask people how much processed
foods they eat and then follow them over time, looking for correlations between processed food
consumption and their body composition.
These types of studies have been conducted, and they’ve found correlations between
consumption of processed foods and obesity. For example, a cross-sectional study published in
2018 compared the consumption of processed foods and the prevalence of obesity in 19
European countries and found that countries where people eat more processed foods also have
a greater prevalence of obesity.1 A prospective cohort study published in 2016 followed nearly
8,500 university graduates in Spain and found that those who ate more processed foods were
more likely to be overweight or obese 9 years later.2
1.10.1 49297 From these results, can we conclude that eating more processed food causes
weight gain? Nope. It’s a tempting conclusion, but this brings us to the first major problem with
nutrition research: Observational studies can only show that two variables (eating processed
foods and obesity, in this case) are correlated, not that one causes the other. This distinction is
especially important in nutrition because diet is intertwined with many other lifestyle and
socioeconomic factors that also affect health outcomes. For example, people who eat more
processed food might also eat fewer fruits and vegetables, exercise or sleep less, have more
stress, or have less access to preventative healthcare. These are just a few of the confounding
factors that could explain the observed correlation between processed food consumption and
weight gain. Weight gain might have nothing to do with processed food and instead be driven
by one or all of these factors, or others that we haven’t considered.
The second major problem with observational nutrition research is that it’s difficult to accurately
quantify what and how much people eat, especially over long periods of time. Epidemiological
studies usually rely on questionnaires that ask people to remember how much food they ate,
but people are notoriously bad at remembering this type of information, and sometimes we
fudge the truth. For example, you might remember that you had a cup of coffee but forget that
you added cream, completely forget about a mid-morning muffin snack, or guess that you ate 2
cups of veggies when it was closer to 1.5 cups. And many diet questionnaires, called food
frequency questionnaires, ask people to recollect and mentally average their food and beverage
intake for the last 12 months, not just yesterday. The image below shows part of a page from a
24-page National Health and Nutrition Examination Survey (NHANES) food questionnaire, a
national survey often used for research on country-wide dietary patterns. As you can see, these
questions are detailed, and there’s plenty of room for small errors to accumulate.
Figure 2.5. A sample page from the NHANES Food Questionnaire.
A third challenge in nutrition research is that diet is just so complex. Stanford physician and
researcher John Ioannidis, a frequent critic of observational nutrition research, described the
complexity of diet in a 2018 editorial published in JAMA: “Individuals consume thousands of
chemicals in millions of possible daily combinations. For instance, there are more than 250,000
different foods and even more potentially edible items, with 300,000 edible plants alone.” He
also points out that how an individual responds to a particular dietary pattern can be influenced
by genetics, age, and the way they metabolize nutrients. “Disentangling the potential influence
on health outcomes of a single dietary component from these other variable is challenging, if
not impossible,” Ioannidis wrote.3
1.10.2 49297
Returning to the question of processed foods, all three of these challenges impact how we
interpret observational studies that show a correlation between processed food consumption
and weight gain. It doesn’t mean that these studies are useless, but we want to be aware of
their limitations and consider other ways to test the hypothesis. One way to overcome these
challenges is to conduct a randomized controlled trial (RCT), the study design that gives us the
highest quality evidence. RCTs are time and funding-intensive experiments, so they’re usually
only conducted after consistent evidence from observational and laboratory studies has
accumulated.
It turns out that there has been a randomized controlled trial of processed foods and weight
gain. It was funded by the National Institutes of Health and published in 2019 in the journal Cell
Metabolism.4 In this study, 20 participants lived in the NIH’s Clinical Center for one month,
where they consumed only processed foods for two weeks and only unprocessed foods for
another two weeks, and they could eat as much or as little as they liked during each of these
periods. The diets were carefully designed by dietitians so that they were matched in calories,
sugar, fat, fiber, and macronutrients, and the exact amounts consumed by the participants
were measured every day (solving the problem of measuring diet complexity and accurately
describing what and how much people eat every day).
The study found that people ate about 500 kilocalories more and gained about a pound per
week when they were eating processed foods. This study design could show causation, not just
correlation, because the other nutritional factors like calories, sugar, fat, fiber, and
macronutrients were held constant, and the diets were tested in the same people, so other
factors such as genetics, sleep, stress, and exercise were constant between the two types of
diets. (This was an example of a crossover randomized controlled trial, in which each subject
serves as their own control, and they completed the processed and unprocessed phases of the
trial in random order.)
Figure 2.6. At left, researchers Kevin Hall and Stephanie Chung talk with one of the processed
foods trial participants at the NIH Clinical Center, an inpatient facility where participants lived
for the duration of the study. At right, an NIH worker prepares meals for participants in the
center’s kitchen. All meals were provided for study participants to carefully control their diet
during the trial.
This study suggested something very important—that food processing causes people to eat
more food and gain weight. However, even the best study design has limitations. For one thing,
this study was small (just 20 participants), and it only lasted for two
1.10.3 49297 weeks, so we don’t know if the findings apply to the general population over
a lifetime of complex, ever-changing diets. The next steps will be to try to repeat the study in
another group of people to see if the finding holds and to design studies to figure out why
processed foods cause increased caloric intake.
As you evaluate nutrition research, especially observational studies, keep in mind the inherent
challenges of nutrition research and look for randomized controlled trials that can help solve
those challenges. Even for randomized controlled trials, consider their limitations, and know that
one study is never enough to fully answer a question in the complex field of nutrition.
Industry Influence: Follow the Money
Understanding how diet influences health is a pressing need. By some estimates, a suboptimal
diet is the single greatest changeable risk factor contributing to death and disability worldwide,
and in the United States, the cost of diet-related chronic diseases are estimated to be as high
as $1 trillion each year.5 Yet, for all its importance, nutrition science has long suffered from a
lack of government investment, with only about 5 percent of the National Institutes of Health
(NIH) budget, or $1.8 billion, directed towards research on how the foods we eat affect our
health, according to a 2019 investigation by Politico. “In 2018, NIH funding for cancer, which
affects just under 9 percent of the population, was $6.3 billion. Funding for obesity, which
affects about 30 percent of the country, was about $1 billion,” the article noted.6
With so little government funding for nutrition science, who is funding the rest of the studies
that feed the constant news cycle? Many are funded by food companies and industry groups,
either to conduct studies in their own research divisions or in the form of grants given to
university scientists. That’s problematic, because food companies and industry groups have an
inherent bias or conflict of interest. Their primary goal is to promote their products and to sell
more of them—not to advance knowledge of food and health—and this affects how they frame
research questions, design and interpret studies, and report their results.
Marion Nestle, a retired nutrition professor at New York University, has written extensively
about this problem. For a year in 2015-2016, she informally tracked industry-funded studies and
found that 90 percent of the time, their conclusions benefited the industry that funded them. In
another example, a 2013 meta-analysis found that among studies that looked at whether soda
consumption contributed to obesity, those funded by the soda industry were five times more
likely to conclude that it doesn’t contribute to obesity compared to those not funded by the
industry.7 (Consider the processed foods RCT we just discussed. It was funded by the National
Institutes of Health, which doesn’t have a stake in the results. Would you trust the results of a
study of processed foods if it was funded by Nabisco? Or for that matter, the Broccoli Growers
of America? Probably not.)
There’s likely a long history of biased nutrition research influencing dietary advice. For example,
in the 1960s, the sugar industry paid well-respected academic scientists to publish research
concluding that it was fat—not sugar—that was detrimental to heart health.8 (Both too much
fat and too much sugar can negatively affect heart health, but it benefited the sugar industry to
focus the blame on fat.) As recently as 2015, Coca-Cola was funding research meant to
promote lack of physical activity as the main cause of obesity, shifting blame away from dietary
factors, such as drinking soda.9 When food companies drive the narrative coming out of
nutrition research, this can potentially impact public policy.
Media attention has made researchers and policy makers much more aware of the problems
with industry funding and conflicts of interest in nutrition research, and they’re working to solve
them. But regardless, if you see reports of a study that shows that blueberries can block
bladder infections, pistachios can prevent pancreatitis, or cinnamon can cure cancer… well, you
should be skeptical, and always check the funding source. Studies on a single type of food are
almost always industry-funded.
How to find clarity in a complex field
Let’s review some of the key issues:
Nutrition research is really difficult to do well. We want to know how nutrition relates to health
over the long term, but it’s hard to quantify how people eat over a lifetime and track them for
long enough to see an impact.
We often rely on observational studies, which can only show that two variables are correlated,
not that one causes the other. Randomized controlled trials are rare, and they’re often small,
short-term studies that may or may not tell us what happens in the real world.
Diet is exceptionally complex, with countless combinations of different nutrients and foods.
One study is never enough to fully answer a question in the complex field of nutrition.
Nutrition research is often funded by the food industry, which can be biased towards results
that benefit business, not human health.
It turns out that there has been a randomized controlled trial of processed foods and weight
gain. It was funded by the National Institutes of Health and published in 2019 in the journal Cell
Metabolism.4 In this study, 20 participants lived in the NIH’s Clinical Center for one month,
where they consumed only processed foods for two weeks and only unprocessed foods for
another two weeks, and they could eat as much or as little as they liked during each of these
periods. The diets were carefully designed by dietitians so that they were matched in calories,
sugar, fat, fiber, and macronutrients, and the exact amounts consumed by the participants
were measured every day (solving the problem of measuring diet complexity and accurately
describing what and how much people eat every day).
The study found that people ate about 500 kilocalories more and gained about a pound per
week when they were eating processed foods. This study design could show causation, not just
correlation, because the other nutritional factors like calories, sugar, fat, fiber, and
macronutrients were held constant, and the diets were tested in the same people, so other
factors such as genetics, sleep, stress, and exercise were constant between the two types of
diets. (This was an example of a crossover randomized controlled trial, in which each subject
serves as their own control, and they completed the processed and unprocessed phases of the
trial in random order.)
Figure 2.6. At left, researchers Kevin Hall and Stephanie Chung talk with one of the processed
foods trial participants at the NIH Clinical Center, an inpatient facility where participants lived
for the duration of the study. At right, an NIH worker prepares meals for participants in the
center’s kitchen. All meals were provided for study participants to carefully control their diet
during the trial.
This study suggested something very important—that food processing causes people to eat
more food and gain weight. However, even the best study design has limitations. For one thing,
this study was small (just 20 participants), and it only lasted for two
1.10.3 49297 weeks, so we don’t know if the findings apply to the general population over
a lifetime of complex, ever-changing diets. The next steps will be to try to repeat the study in
another group of people to see if the finding holds and to design studies to figure out why
processed foods cause increased caloric intake.
As you evaluate nutrition research, especially observational studies, keep in mind the inherent
challenges of nutrition research and look for randomized controlled trials that can help solve
those challenges. Even for randomized controlled trials, consider their limitations, and know that
one study is never enough to fully answer a question in the complex field of nutrition.
Industry Influence: Follow the Money
Understanding how diet influences health is a pressing need. By some estimates, a suboptimal
diet is the single greatest changeable risk factor contributing to death and disability worldwide,
and in the United States, the cost of diet-related chronic diseases are estimated to be as high
as $1 trillion each year.5 Yet, for all its importance, nutrition science has long suffered from a
lack of government investment, with only about 5 percent of the National Institutes of Health
(NIH) budget, or $1.8 billion, directed towards research on how the foods we eat affect our
health, according to a 2019 investigation by Politico. “In 2018, NIH funding for cancer, which
affects just under 9 percent of the population, was $6.3 billion. Funding for obesity, which
affects about 30 percent of the country, was about $1 billion,” the article noted.6
With so little government funding for nutrition science, who is funding the rest of the studies
that feed the constant news cycle? Many are funded by food companies and industry groups,
either to conduct studies in their own research divisions or in the form of grants given to
university scientists. That’s problematic, because food companies and industry groups have an
inherent bias or conflict of interest. Their primary goal is to promote their products and to sell
more of them—not to advance knowledge of food and health—and this affects how they frame
research questions, design and interpret studies, and report their results.
Marion Nestle, a retired nutrition professor at New York University, has written extensively
about this problem. For a year in 2015-2016, she informally tracked industry-funded studies and
found that 90 percent of the time, their conclusions benefited the industry that funded them. In
another example, a 2013 meta-analysis found that among studies that looked at whether soda
consumption contributed to obesity, those funded by the soda industry were five times more
likely to conclude that it doesn’t contribute to obesity compared to those not funded by the
industry.7 (Consider the processed foods RCT we just discussed. It was funded by the National
Institutes of Health, which doesn’t have a stake in the results. Would you trust the results of a
study of processed foods if it was funded by Nabisco? Or for that matter, the Broccoli Growers
of America? Probably not.)
There’s likely a long history of biased nutrition research influencing dietary advice. For example,
in the 1960s, the sugar industry paid well-respected academic scientists to publish research
concluding that it was fat—not sugar—that was detrimental to heart health.8 (Both too much
fat and too much sugar can negatively affect heart health, but it benefited the sugar industry to
focus the blame on fat.) As recently as 2015, Coca-Cola was funding research meant to
promote lack of physical activity as the main cause of obesity, shifting blame away from dietary
factors, such as drinking soda.9 When food companies drive the narrative coming out of
nutrition research, this can potentially impact public policy.
Media attention has made researchers and policy makers much more aware of the problems
with industry funding and conflicts of interest in nutrition research, and they’re working to solve
them. But regardless, if you see reports of a study that shows that blueberries can block
bladder infections, pistachios can prevent pancreatitis, or cinnamon can cure cancer… well, you
should be skeptical, and always check the funding source. Studies on a single type of food are
almost always industry-funded.
It turns out that there has been a randomized controlled trial of processed foods and weight
gain. It was funded by the National Institutes of Health and published in 2019 in the journal Cell
Metabolism.4 In this study, 20 participants lived in the NIH’s Clinical Center for one month,
where they consumed only processed foods for two weeks and only unprocessed foods for
another two weeks, and they could eat as much or as little as they liked during each of these
periods. The diets were carefully designed by dietitians so that they were matched in calories,
sugar, fat, fiber, and macronutrients, and the exact amounts consumed by the participants
were measured every day (solving the problem of measuring diet complexity and accurately
describing what and how much people eat every day).
The study found that people ate about 500 kilocalories more and gained about a pound per
week when they were eating processed foods. This study design could show causation, not just
correlation, because the other nutritional factors like calories, sugar, fat, fiber, and
macronutrients were held constant, and the diets were tested in the same people, so other
factors such as genetics, sleep, stress, and exercise were constant between the two types of
diets. (This was an example of a crossover randomized controlled trial, in which each subject
serves as their own control, and they completed the processed and unprocessed phases of the
trial in random order.)
Figure 2.6. At left, researchers Kevin Hall and Stephanie Chung talk with one of the processed
foods trial participants at the NIH Clinical Center, an inpatient facility where participants lived
for the duration of the study. At right, an NIH worker prepares meals for participants in the
center’s kitchen. All meals were provided for study participants to carefully control their diet
during the trial.
This study suggested something very important—that food processing causes people to eat
more food and gain weight. However, even the best study design has limitations. For one thing,
this study was small (just 20 participants), and it only lasted for two
1.10.3 49297 weeks, so we don’t know if the findings apply to the general population over
a lifetime of complex, ever-changing diets. The next steps will be to try to repeat the study in
another group of people to see if the finding holds and to design studies to figure out why
processed foods cause increased caloric intake.
As you evaluate nutrition research, especially observational studies, keep in mind the inherent
challenges of nutrition research and look for randomized controlled trials that can help solve
those challenges. Even for randomized controlled trials, consider their limitations, and know that
one study is never enough to fully answer a question in the complex field of nutrition.
Industry Influence: Follow the Money
Understanding how diet influences health is a pressing need. By some estimates, a suboptimal
diet is the single greatest changeable risk factor contributing to death and disability worldwide,
and in the United States, the cost of diet-related chronic diseases are estimated to be as high
as $1 trillion each year.5 Yet, for all its importance, nutrition science has long suffered from a
lack of government investment, with only about 5 percent of the National Institutes of Health
(NIH) budget, or $1.8 billion, directed towards research on how the foods we eat affect our
health, according to a 2019 investigation by Politico. “In 2018, NIH funding for cancer, which
affects just under 9 percent of the population, was $6.3 billion. Funding for obesity, which
affects about 30 percent of the country, was about $1 billion,” the article noted.6
With so little government funding for nutrition science, who is funding the rest of the studies
that feed the constant news cycle? Many are funded by food companies and industry groups,
either to conduct studies in their own research divisions or in the form of grants given to
university scientists. That’s problematic, because food companies and industry groups have an
inherent bias or conflict of interest. Their primary goal is to promote their products and to sell
more of them—not to advance knowledge of food and health—and this affects how they frame
research questions, design and interpret studies, and report their results.
Marion Nestle, a retired nutrition professor at New York University, has written extensively
about this problem. For a year in 2015-2016, she informally tracked industry-funded studies and
found that 90 percent of the time, their conclusions benefited the industry that funded them. In
another example, a 2013 meta-analysis found that among studies that looked at whether soda
consumption contributed to obesity, those funded by the soda industry were five times more
likely to conclude that it doesn’t contribute to obesity compared to those not funded by the
industry.7 (Consider the processed foods RCT we just discussed. It was funded by the National
Institutes of Health, which doesn’t have a stake in the results. Would you trust the results of a
study of processed foods if it was funded by Nabisco? Or for that matter, the Broccoli Growers
of America? Probably not.)
There’s likely a long history of biased nutrition research influencing dietary advice. For example,
in the 1960s, the sugar industry paid well-respected academic scientists to publish research
concluding that it was fat—not sugar—that was detrimental to heart health.8 (Both too much
fat and too much sugar can negatively affect heart health, but it benefited the sugar industry to
focus the blame on fat.) As recently as 2015, Coca-Cola was funding research meant to
promote lack of physical activity as the main cause of obesity, shifting blame away from dietary
factors, such as drinking soda.9 When food companies drive the narrative coming out of
nutrition research, this can potentially impact public policy.
Media attention has made researchers and policy makers much more aware of the problems
with industry funding and conflicts of interest in nutrition research, and they’re working to solve
them. But regardless, if you see reports of a study that shows that blueberries can block
bladder infections, pistachios can prevent pancreatitis, or cinnamon can cure cancer… well, you
should be skeptical, and always check the funding source. Studies on a single type of food are
almost always industry-funded.
It turns out that there has been a randomized controlled trial of processed foods and weight
gain. It was funded by the National Institutes of Health and published in 2019 in the journal Cell
Metabolism.4 In this study, 20 participants lived in the NIH’s Clinical Center for one month,
where they consumed only processed foods for two weeks and only unprocessed foods for
another two weeks, and they could eat as much or as little as they liked during each of these
periods. The diets were carefully designed by dietitians so that they were matched in calories,
sugar, fat, fiber, and macronutrients, and the exact amounts consumed by the participants
were measured every day (solving the problem of measuring diet complexity and accurately
describing what and how much people eat every day).
The study found that people ate about 500 kilocalories more and gained about a pound per
week when they were eating processed foods. This study design could show causation, not just
correlation, because the other nutritional factors like calories, sugar, fat, fiber, and
macronutrients were held constant, and the diets were tested in the same people, so other
factors such as genetics, sleep, stress, and exercise were constant between the two types of
diets. (This was an example of a crossover randomized controlled trial, in which each subject
serves as their own control, and they completed the processed and unprocessed phases of the
trial in random order.)
Figure 2.6. At left, researchers Kevin Hall and Stephanie Chung talk with one of the processed
foods trial participants at the NIH Clinical Center, an inpatient facility where participants lived
for the duration of the study. At right, an NIH worker prepares meals for participants in the
center’s kitchen. All meals were provided for study participants to carefully control their diet
during the trial.
This study suggested something very important—that food processing causes people to eat
more food and gain weight. However, even the best study design has limitations. For one thing,
this study was small (just 20 participants), and it only lasted for two
1.10.3 49297 weeks, so we don’t know if the findings apply to the general population over
a lifetime of complex, ever-changing diets. The next steps will be to try to repeat the study in
another group of people to see if the finding holds and to design studies to figure out why
processed foods cause increased caloric intake.
As you evaluate nutrition research, especially observational studies, keep in mind the inherent
challenges of nutrition research and look for randomized controlled trials that can help solve
those challenges. Even for randomized controlled trials, consider their limitations, and know that
one study is never enough to fully answer a question in the complex field of nutrition.
Industry Influence: Follow the Money
Understanding how diet influences health is a pressing need. By some estimates, a suboptimal
diet is the single greatest changeable risk factor contributing to death and disability worldwide,
and in the United States, the cost of diet-related chronic diseases are estimated to be as high
as $1 trillion each year.5 Yet, for all its importance, nutrition science has long suffered from a
lack of government investment, with only about 5 percent of the National Institutes of Health
(NIH) budget, or $1.8 billion, directed towards research on how the foods we eat affect our
health, according to a 2019 investigation by Politico. “In 2018, NIH funding for cancer, which
affects just under 9 percent of the population, was $6.3 billion. Funding for obesity, which
affects about 30 percent of the country, was about $1 billion,” the article noted.6
With so little government funding for nutrition science, who is funding the rest of the studies
that feed the constant news cycle? Many are funded by food companies and industry groups,
either to conduct studies in their own research divisions or in the form of grants given to
university scientists. That’s problematic, because food companies and industry groups have an
inherent bias or conflict of interest. Their primary goal is to promote their products and to sell
more of them—not to advance knowledge of food and health—and this affects how they frame
research questions, design and interpret studies, and report their results.
Marion Nestle, a retired nutrition professor at New York University, has written extensively
about this problem. For a year in 2015-2016, she informally tracked industry-funded studies and
found that 90 percent of the time, their conclusions benefited the industry that funded them. In
another example, a 2013 meta-analysis found that among studies that looked at whether soda
consumption contributed to obesity, those funded by the soda industry were five times more
likely to conclude that it doesn’t contribute to obesity compared to those not funded by the
industry.7 (Consider the processed foods RCT we just discussed. It was funded by the National
Institutes of Health, which doesn’t have a stake in the results. Would you trust the results of a
study of processed foods if it was funded by Nabisco? Or for that matter, the Broccoli Growers
of America? Probably not.)
There’s likely a long history of biased nutrition research influencing dietary advice. For example,
in the 1960s, the sugar industry paid well-respected academic scientists to publish research
concluding that it was fat—not sugar—that was detrimental to heart health.8 (Both too much
fat and too much sugar can negatively affect heart health, but it benefited the sugar industry to
focus the blame on fat.) As recently as 2015, Coca-Cola was funding research meant to
promote lack of physical activity as the main cause of obesity, shifting blame away from dietary
factors, such as drinking soda.9 When food companies drive the narrative coming out of
nutrition research, this can potentially impact public policy.
Media attention has made researchers and policy makers much more aware of the problems
with industry funding and conflicts of interest in nutrition research, and they’re working to solve
them. But regardless, if you see reports of a study that shows that blueberries can block
bladder infections, pistachios can prevent pancreatitis, or cinnamon can cure cancer… well, you
should be skeptical, and always check the funding source. Studies on a single type of food are
almost always industry-funded.
It turns out that there has been a randomized controlled trial of processed foods and weight
gain. It was funded by the National Institutes of Health and published in 2019 in the journal Cell
Metabolism.4 In this study, 20 participants lived in the NIH’s Clinical Center for one month,
where they consumed only processed foods for two weeks and only unprocessed foods for
another two weeks, and they could eat as much or as little as they liked during each of these
periods. The diets were carefully designed by dietitians so that they were matched in calories,
sugar, fat, fiber, and macronutrients, and the exact amounts consumed by the participants
were measured every day (solving the problem of measuring diet complexity and accurately
describing what and how much people eat every day).
The study found that people ate about 500 kilocalories more and gained about a pound per
week when they were eating processed foods. This study design could show causation, not just
correlation, because the other nutritional factors like calories, sugar, fat, fiber, and
macronutrients were held constant, and the diets were tested in the same people, so other
factors such as genetics, sleep, stress, and exercise were constant between the two types of
diets. (This was an example of a crossover randomized controlled trial, in which each subject
serves as their own control, and they completed the processed and unprocessed phases of the
trial in random order.)
Figure 2.6. At left, researchers Kevin Hall and Stephanie Chung talk with one of the processed
foods trial participants at the NIH Clinical Center, an inpatient facility where participants lived
for the duration of the study. At right, an NIH worker prepares meals for participants in the
center’s kitchen. All meals were provided for study participants to carefully control their diet
during the trial.
This study suggested something very important—that food processing causes people to eat
more food and gain weight. However, even the best study design has limitations. For one thing,
this study was small (just 20 participants), and it only lasted for two
1.10.3 49297 weeks, so we don’t know if the findings apply to the general population over
a lifetime of complex, ever-changing diets. The next steps will be to try to repeat the study in
another group of people to see if the finding holds and to design studies to figure out why
processed foods cause increased caloric intake.
As you evaluate nutrition research, especially observational studies, keep in mind the inherent
challenges of nutrition research and look for randomized controlled trials that can help solve
those challenges. Even for randomized controlled trials, consider their limitations, and know that
one study is never enough to fully answer a question in the complex field of nutrition.
Industry Influence: Follow the Money
Understanding how diet influences health is a pressing need. By some estimates, a suboptimal
diet is the single greatest changeable risk factor contributing to death and disability worldwide,
and in the United States, the cost of diet-related chronic diseases are estimated to be as high
as $1 trillion each year.5 Yet, for all its importance, nutrition science has long suffered from a
lack of government investment, with only about 5 percent of the National Institutes of Health
(NIH) budget, or $1.8 billion, directed towards research on how the foods we eat affect our
health, according to a 2019 investigation by Politico. “In 2018, NIH funding for cancer, which
affects just under 9 percent of the population, was $6.3 billion. Funding for obesity, which
affects about 30 percent of the country, was about $1 billion,” the article noted.6
With so little government funding for nutrition science, who is funding the rest of the studies
that feed the constant news cycle? Many are funded by food companies and industry groups,
either to conduct studies in their own research divisions or in the form of grants given to
university scientists. That’s problematic, because food companies and industry groups have an
inherent bias or conflict of interest. Their primary goal is to promote their products and to sell
more of them—not to advance knowledge of food and health—and this affects how they frame
research questions, design and interpret studies, and report their results.
Marion Nestle, a retired nutrition professor at New York University, has written extensively
about this problem. For a year in 2015-2016, she informally tracked industry-funded studies and
found that 90 percent of the time, their conclusions benefited the industry that funded them. In
another example, a 2013 meta-analysis found that among studies that looked at whether soda
consumption contributed to obesity, those funded by the soda industry were five times more
likely to conclude that it doesn’t contribute to obesity compared to those not funded by the
industry.7 (Consider the processed foods RCT we just discussed. It was funded by the National
Institutes of Health, which doesn’t have a stake in the results. Would you trust the results of a
study of processed foods if it was funded by Nabisco? Or for that matter, the Broccoli Growers
of America? Probably not.)
There’s likely a long history of biased nutrition research influencing dietary advice. For example,
in the 1960s, the sugar industry paid well-respected academic scientists to publish research
concluding that it was fat—not sugar—that was detrimental to heart health.8 (Both too much
fat and too much sugar can negatively affect heart health, but it benefited the sugar industry to
focus the blame on fat.) As recently as 2015, Coca-Cola was funding research meant to
promote lack of physical activity as the main cause of obesity, shifting blame away from dietary
factors, such as drinking soda.9 When food companies drive the narrative coming out of
nutrition research, this can potentially impact public policy.
Media attention has made researchers and policy makers much more aware of the problems
with industry funding and conflicts of interest in nutrition research, and they’re working to solve
them. But regardless, if you see reports of a study that shows that blueberries can block
bladder infections, pistachios can prevent pancreatitis, or cinnamon can cure cancer… well, you
should be skeptical, and always check the funding source. Studies on a single type of food are
almost always industry-funded.
It turns out that there has been a randomized controlled trial of processed foods and weight
gain. It was funded by the National Institutes of Health and published in 2019 in the journal Cell
Metabolism.4 In this study, 20 participants lived in the NIH’s Clinical Center for one month,
where they consumed only processed foods for two weeks and only unprocessed foods for
another two weeks, and they could eat as much or as little as they liked during each of these
periods. The diets were carefully designed by dietitians so that they were matched in calories,
sugar, fat, fiber, and macronutrients, and the exact amounts consumed by the participants
were measured every day (solving the problem of measuring diet complexity and accurately
describing what and how much people eat every day).
The study found that people ate about 500 kilocalories more and gained about a pound per
week when they were eating processed foods. This study design could show causation, not just
correlation, because the other nutritional factors like calories, sugar, fat, fiber, and
macronutrients were held constant, and the diets were tested in the same people, so other
factors such as genetics, sleep, stress, and exercise were constant between the two types of
diets. (This was an example of a crossover randomized controlled trial, in which each subject
serves as their own control, and they completed the processed and unprocessed phases of the
trial in random order.)
Figure 2.6. At left, researchers Kevin Hall and Stephanie Chung talk with one of the processed
foods trial participants at the NIH Clinical Center, an inpatient facility where participants lived
for the duration of the study. At right, an NIH worker prepares meals for participants in the
center’s kitchen. All meals were provided for study participants to carefully control their diet
during the trial.
This study suggested something very important—that food processing causes people to eat
more food and gain weight. However, even the best study design has limitations. For one thing,
this study was small (just 20 participants), and it only lasted for two
1.10.3 49297 weeks, so we don’t know if the findings apply to the general population over
a lifetime of complex, ever-changing diets. The next steps will be to try to repeat the study in
another group of people to see if the finding holds and to design studies to figure out why
processed foods cause increased caloric intake.
As you evaluate nutrition research, especially observational studies, keep in mind the inherent
challenges of nutrition research and look for randomized controlled trials that can help solve
those challenges. Even for randomized controlled trials, consider their limitations, and know that
one study is never enough to fully answer a question in the complex field of nutrition.
Industry Influence: Follow the Money
Understanding how diet influences health is a pressing need. By some estimates, a suboptimal
diet is the single greatest changeable risk factor contributing to death and disability worldwide,
and in the United States, the cost of diet-related chronic diseases are estimated to be as high
as $1 trillion each year.5 Yet, for all its importance, nutrition science has long suffered from a
lack of government investment, with only about 5 percent of the National Institutes of Health
(NIH) budget, or $1.8 billion, directed towards research on how the foods we eat affect our
health, according to a 2019 investigation by Politico. “In 2018, NIH funding for cancer, which
affects just under 9 percent of the population, was $6.3 billion. Funding for obesity, which
affects about 30 percent of the country, was about $1 billion,” the article noted.6
With so little government funding for nutrition science, who is funding the rest of the studies
that feed the constant news cycle? Many are funded by food companies and industry groups,
either to conduct studies in their own research divisions or in the form of grants given to
university scientists. That’s problematic, because food companies and industry groups have an
inherent bias or conflict of interest. Their primary goal is to promote their products and to sell
more of them—not to advance knowledge of food and health—and this affects how they frame
research questions, design and interpret studies, and report their results.
Marion Nestle, a retired nutrition professor at New York University, has written extensively
about this problem. For a year in 2015-2016, she informally tracked industry-funded studies and
found that 90 percent of the time, their conclusions benefited the industry that funded them. In
another example, a 2013 meta-analysis found that among studies that looked at whether soda
consumption contributed to obesity, those funded by the soda industry were five times more
likely to conclude that it doesn’t contribute to obesity compared to those not funded by the
industry.7 (Consider the processed foods RCT we just discussed. It was funded by the National
Institutes of Health, which doesn’t have a stake in the results. Would you trust the results of a
study of processed foods if it was funded by Nabisco? Or for that matter, the Broccoli Growers
of America? Probably not.)
There’s likely a long history of biased nutrition research influencing dietary advice. For example,
in the 1960s, the sugar industry paid well-respected academic scientists to publish research
concluding that it was fat—not sugar—that was detrimental to heart health.8 (Both too much
fat and too much sugar can negatively affect heart health, but it benefited the sugar industry to
focus the blame on fat.) As recently as 2015, Coca-Cola was funding research meant to
promote lack of physical activity as the main cause of obesity, shifting blame away from dietary
factors, such as drinking soda.9 When food companies drive the narrative coming out of
nutrition research, this can potentially impact public policy.
Media attention has made researchers and policy makers much more aware of the problems
with industry funding and conflicts of interest in nutrition research, and they’re working to solve
them. But regardless, if you see reports of a study that shows that blueberries can block
bladder infections, pistachios can prevent pancreatitis, or cinnamon can cure cancer… well, you
should be skeptical, and always check the funding source. Studies on a single type of food are
almost always industry-funded.
It turns out that there has been a randomized controlled trial of processed foods and weight
gain. It was funded by the National Institutes of Health and published in 2019 in the journal Cell
Metabolism.4 In this study, 20 participants lived in the NIH’s Clinical Center for one month,
where they consumed only processed foods for two weeks and only unprocessed foods for
another two weeks, and they could eat as much or as little as they liked during each of these
periods. The diets were carefully designed by dietitians so that they were matched in calories,
sugar, fat, fiber, and macronutrients, and the exact amounts consumed by the participants
were measured every day (solving the problem of measuring diet complexity and accurately
describing what and how much people eat every day).
The study found that people ate about 500 kilocalories more and gained about a pound per
week when they were eating processed foods. This study design could show causation, not just
correlation, because the other nutritional factors like calories, sugar, fat, fiber, and
macronutrients were held constant, and the diets were tested in the same people, so other
factors such as genetics, sleep, stress, and exercise were constant between the two types of
diets. (This was an example of a crossover randomized controlled trial, in which each subject
serves as their own control, and they completed the processed and unprocessed phases of the
trial in random order.)
Figure 2.6. At left, researchers Kevin Hall and Stephanie Chung talk with one of the processed
foods trial participants at the NIH Clinical Center, an inpatient facility where participants lived
for the duration of the study. At right, an NIH worker prepares meals for participants in the
center’s kitchen. All meals were provided for study participants to carefully control their diet
during the trial.
This study suggested something very important—that food processing causes people to eat
more food and gain weight. However, even the best study design has limitations. For one thing,
this study was small (just 20 participants), and it only lasted for two
1.10.3 49297 weeks, so we don’t know if the findings apply to the general population over
a lifetime of complex, ever-changing diets. The next steps will be to try to repeat the study in
another group of people to see if the finding holds and to design studies to figure out why
processed foods cause increased caloric intake.
As you evaluate nutrition research, especially observational studies, keep in mind the inherent
challenges of nutrition research and look for randomized controlled trials that can help solve
those challenges. Even for randomized controlled trials, consider their limitations, and know that
one study is never enough to fully answer a question in the complex field of nutrition.
Industry Influence: Follow the Money
Understanding how diet influences health is a pressing need. By some estimates, a suboptimal
diet is the single greatest changeable risk factor contributing to death and disability worldwide,
and in the United States, the cost of diet-related chronic diseases are estimated to be as high
as $1 trillion each year.5 Yet, for all its importance, nutrition science has long suffered from a
lack of government investment, with only about 5 percent of the National Institutes of Health
(NIH) budget, or $1.8 billion, directed towards research on how the foods we eat affect our
health, according to a 2019 investigation by Politico. “In 2018, NIH funding for cancer, which
affects just under 9 percent of the population, was $6.3 billion. Funding for obesity, which
affects about 30 percent of the country, was about $1 billion,” the article noted.6
With so little government funding for nutrition science, who is funding the rest of the studies
that feed the constant news cycle? Many are funded by food companies and industry groups,
either to conduct studies in their own research divisions or in the form of grants given to
university scientists. That’s problematic, because food companies and industry groups have an
inherent bias or conflict of interest. Their primary goal is to promote their products and to sell
more of them—not to advance knowledge of food and health—and this affects how they frame
research questions, design and interpret studies, and report their results.
Marion Nestle, a retired nutrition professor at New York University, has written extensively
about this problem. For a year in 2015-2016, she informally tracked industry-funded studies and
found that 90 percent of the time, their conclusions benefited the industry that funded them. In
another example, a 2013 meta-analysis found that among studies that looked at whether soda
consumption contributed to obesity, those funded by the soda industry were five times more
likely to conclude that it doesn’t contribute to obesity compared to those not funded by the
industry.7 (Consider the processed foods RCT we just discussed. It was funded by the National
Institutes of Health, which doesn’t have a stake in the results. Would you trust the results of a
study of processed foods if it was funded by Nabisco? Or for that matter, the Broccoli Growers
of America? Probably not.)
There’s likely a long history of biased nutrition research influencing dietary advice. For example,
in the 1960s, the sugar industry paid well-respected academic scientists to publish research
concluding that it was fat—not sugar—that was detrimental to heart health.8 (Both too much
fat and too much sugar can negatively affect heart health, but it benefited the sugar industry to
focus the blame on fat.) As recently as 2015, Coca-Cola was funding research meant to
promote lack of physical activity as the main cause of obesity, shifting blame away from dietary
factors, such as drinking soda.9 When food companies drive the narrative coming out of
nutrition research, this can potentially impact public policy.
Media attention has made researchers and policy makers much more aware of the problems
with industry funding and conflicts of interest in nutrition research, and they’re working to solve
them. But regardless, if you see reports of a study that shows that blueberries can block
bladder infections, pistachios can prevent pancreatitis, or cinnamon can cure cancer… well, you
should be skeptical, and always check the funding source. Studies on a single type of food are
almost always industry-funded.
It turns out that there has been a randomized controlled trial of processed foods and weight
gain. It was funded by the National Institutes of Health and published in 2019 in the journal Cell
Metabolism.4 In this study, 20 participants lived in the NIH’s Clinical Center for one month,
where they consumed only processed foods for two weeks and only unprocessed foods for
another two weeks, and they could eat as much or as little as they liked during each of these
periods. The diets were carefully designed by dietitians so that they were matched in calories,
sugar, fat, fiber, and macronutrients, and the exact amounts consumed by the participants
were measured every day (solving the problem of measuring diet complexity and accurately
describing what and how much people eat every day).
The study found that people ate about 500 kilocalories more and gained about a pound per
week when they were eating processed foods. This study design could show causation, not just
correlation, because the other nutritional factors like calories, sugar, fat, fiber, and
macronutrients were held constant, and the diets were tested in the same people, so other
factors such as genetics, sleep, stress, and exercise were constant between the two types of
diets. (This was an example of a crossover randomized controlled trial, in which each subject
serves as their own control, and they completed the processed and unprocessed phases of the
trial in random order.)
Figure 2.6. At left, researchers Kevin Hall and Stephanie Chung talk with one of the processed
foods trial participants at the NIH Clinical Center, an inpatient facility where participants lived
for the duration of the study. At right, an NIH worker prepares meals for participants in the
center’s kitchen. All meals were provided for study participants to carefully control their diet
during the trial.
This study suggested something very important—that food processing causes people to eat
more food and gain weight. However, even the best study design has limitations. For one thing,
this study was small (just 20 participants), and it only lasted for two
1.10.3 49297 weeks, so we don’t know if the findings apply to the general population over
a lifetime of complex, ever-changing diets. The next steps will be to try to repeat the study in
another group of people to see if the finding holds and to design studies to figure out why
processed foods cause increased caloric intake.
As you evaluate nutrition research, especially observational studies, keep in mind the inherent
challenges of nutrition research and look for randomized controlled trials that can help solve
those challenges. Even for randomized controlled trials, consider their limitations, and know that
one study is never enough to fully answer a question in the complex field of nutrition.
Industry Influence: Follow the Money
Understanding how diet influences health is a pressing need. By some estimates, a suboptimal
diet is the single greatest changeable risk factor contributing to death and disability worldwide,
and in the United States, the cost of diet-related chronic diseases are estimated to be as high
as $1 trillion each year.5 Yet, for all its importance, nutrition science has long suffered from a
lack of government investment, with only about 5 percent of the National Institutes of Health
(NIH) budget, or $1.8 billion, directed towards research on how the foods we eat affect our
health, according to a 2019 investigation by Politico. “In 2018, NIH funding for cancer, which
affects just under 9 percent of the population, was $6.3 billion. Funding for obesity, which
affects about 30 percent of the country, was about $1 billion,” the article noted.6
With so little government funding for nutrition science, who is funding the rest of the studies
that feed the constant news cycle? Many are funded by food companies and industry groups,
either to conduct studies in their own research divisions or in the form of grants given to
university scientists. That’s problematic, because food companies and industry groups have an
inherent bias or conflict of interest. Their primary goal is to promote their products and to sell
more of them—not to advance knowledge of food and health—and this affects how they frame
research questions, design and interpret studies, and report their results.
Marion Nestle, a retired nutrition professor at New York University, has written extensively
about this problem. For a year in 2015-2016, she informally tracked industry-funded studies and
found that 90 percent of the time, their conclusions benefited the industry that funded them. In
another example, a 2013 meta-analysis found that among studies that looked at whether soda
consumption contributed to obesity, those funded by the soda industry were five times more
likely to conclude that it doesn’t contribute to obesity compared to those not funded by the
industry.7 (Consider the processed foods RCT we just discussed. It was funded by the National
Institutes of Health, which doesn’t have a stake in the results. Would you trust the results of a
study of processed foods if it was funded by Nabisco? Or for that matter, the Broccoli Growers
of America? Probably not.)
There’s likely a long history of biased nutrition research influencing dietary advice. For example,
in the 1960s, the sugar industry paid well-respected academic scientists to publish research
concluding that it was fat—not sugar—that was detrimental to heart health.8 (Both too much
fat and too much sugar can negatively affect heart health, but it benefited the sugar industry to
focus the blame on fat.) As recently as 2015, Coca-Cola was funding research meant to
promote lack of physical activity as the main cause of obesity, shifting blame away from dietary
factors, such as drinking soda.9 When food companies drive the narrative coming out of
nutrition research, this can potentially impact public policy.
Media attention has made researchers and policy makers much more aware of the problems
with industry funding and conflicts of interest in nutrition research, and they’re working to solve
them. But regardless, if you see reports of a study that shows that blueberries can block
bladder infections, pistachios can prevent pancreatitis, or cinnamon can cure cancer… well, you
should be skeptical, and always check the funding source. Studies on a single type of food are
almost always industry-funded.
It turns out that there has been a randomized controlled trial of processed foods and weight
gain. It was funded by the National Institutes of Health and published in 2019 in the journal Cell
Metabolism.4 In this study, 20 participants lived in the NIH’s Clinical Center for one month,
where they consumed only processed foods for two weeks and only unprocessed foods for
another two weeks, and they could eat as much or as little as they liked during each of these
periods. The diets were carefully designed by dietitians so that they were matched in calories,
sugar, fat, fiber, and macronutrients, and the exact amounts consumed by the participants
were measured every day (solving the problem of measuring diet complexity and accurately
describing what and how much people eat every day).
The study found that people ate about 500 kilocalories more and gained about a pound per
week when they were eating processed foods. This study design could show causation, not just
correlation, because the other nutritional factors like calories, sugar, fat, fiber, and
macronutrients were held constant, and the diets were tested in the same people, so other
factors such as genetics, sleep, stress, and exercise were constant between the two types of
diets. (This was an example of a crossover randomized controlled trial, in which each subject
serves as their own control, and they completed the processed and unprocessed phases of the
trial in random order.)
Figure 2.6. At left, researchers Kevin Hall and Stephanie Chung talk with one of the processed
foods trial participants at the NIH Clinical Center, an inpatient facility where participants lived
for the duration of the study. At right, an NIH worker prepares meals for participants in the
center’s kitchen. All meals were provided for study participants to carefully control their diet
during the trial.
This study suggested something very important—that food processing causes people to eat
more food and gain weight. However, even the best study design has limitations. For one thing,
this study was small (just 20 participants), and it only lasted for two
1.10.3 49297 weeks, so we don’t know if the findings apply to the general population over
a lifetime of complex, ever-changing diets. The next steps will be to try to repeat the study in
another group of people to see if the finding holds and to design studies to figure out why
processed foods cause increased caloric intake.
As you evaluate nutrition research, especially observational studies, keep in mind the inherent
challenges of nutrition research and look for randomized controlled trials that can help solve
those challenges. Even for randomized controlled trials, consider their limitations, and know that
one study is never enough to fully answer a question in the complex field of nutrition.
Industry Influence: Follow the Money
Understanding how diet influences health is a pressing need. By some estimates, a suboptimal
diet is the single greatest changeable risk factor contributing to death and disability worldwide,
and in the United States, the cost of diet-related chronic diseases are estimated to be as high
as $1 trillion each year.5 Yet, for all its importance, nutrition science has long suffered from a
lack of government investment, with only about 5 percent of the National Institutes of Health
(NIH) budget, or $1.8 billion, directed towards research on how the foods we eat affect our
health, according to a 2019 investigation by Politico. “In 2018, NIH funding for cancer, which
affects just under 9 percent of the population, was $6.3 billion. Funding for obesity, which
affects about 30 percent of the country, was about $1 billion,” the article noted.6
With so little government funding for nutrition science, who is funding the rest of the studies
that feed the constant news cycle? Many are funded by food companies and industry groups,
either to conduct studies in their own research divisions or in the form of grants given to
university scientists. That’s problematic, because food companies and industry groups have an
inherent bias or conflict of interest. Their primary goal is to promote their products and to sell
more of them—not to advance knowledge of food and health—and this affects how they frame
research questions, design and interpret studies, and report their results.
Marion Nestle, a retired nutrition professor at New York University, has written extensively
about this problem. For a year in 2015-2016, she informally tracked industry-funded studies and
found that 90 percent of the time, their conclusions benefited the industry that funded them. In
another example, a 2013 meta-analysis found that among studies that looked at whether soda
consumption contributed to obesity, those funded by the soda industry were five times more
likely to conclude that it doesn’t contribute to obesity compared to those not funded by the
industry.7 (Consider the processed foods RCT we just discussed. It was funded by the National
Institutes of Health, which doesn’t have a stake in the results. Would you trust the results of a
study of processed foods if it was funded by Nabisco? Or for that matter, the Broccoli Growers
of America? Probably not.)
There’s likely a long history of biased nutrition research influencing dietary advice. For example,
in the 1960s, the sugar industry paid well-respected academic scientists to publish research
concluding that it was fat—not sugar—that was detrimental to heart health.8 (Both too much
fat and too much sugar can negatively affect heart health, but it benefited the sugar industry to
focus the blame on fat.) As recently as 2015, Coca-Cola was funding research meant to
promote lack of physical activity as the main cause of obesity, shifting blame away from dietary
factors, such as drinking soda.9 When food companies drive the narrative coming out of
nutrition research, this can potentially impact public policy.
Media attention has made researchers and policy makers much more aware of the problems
with industry funding and conflicts of interest in nutrition research, and they’re working to solve
them. But regardless, if you see reports of a study that shows that blueberries can block
bladder infections, pistachios can prevent pancreatitis, or cinnamon can cure cancer… well, you
should be skeptical, and always check the funding source. Studies on a single type of food are
almost always industry-funded.
It turns out that there has been a randomized controlled trial of processed foods and weight
gain. It was funded by the National Institutes of Health and published in 2019 in the journal Cell
Metabolism.4 In this study, 20 participants lived in the NIH’s Clinical Center for one month,
where they consumed only processed foods for two weeks and only unprocessed foods for
another two weeks, and they could eat as much or as little as they liked during each of these
periods. The diets were carefully designed by dietitians so that they were matched in calories,
sugar, fat, fiber, and macronutrients, and the exact amounts consumed by the participants
were measured every day (solving the problem of measuring diet complexity and accurately
describing what and how much people eat every day).
The study found that people ate about 500 kilocalories more and gained about a pound per
week when they were eating processed foods. This study design could show causation, not just
correlation, because the other nutritional factors like calories, sugar, fat, fiber, and
macronutrients were held constant, and the diets were tested in the same people, so other
factors such as genetics, sleep, stress, and exercise were constant between the two types of
diets. (This was an example of a crossover randomized controlled trial, in which each subject
serves as their own control, and they completed the processed and unprocessed phases of the
trial in random order.)
Figure 2.6. At left, researchers Kevin Hall and Stephanie Chung talk with one of the processed
foods trial participants at the NIH Clinical Center, an inpatient facility where participants lived
for the duration of the study. At right, an NIH worker prepares meals for participants in the
center’s kitchen. All meals were provided for study participants to carefully control their diet
during the trial.
This study suggested something very important—that food processing causes people to eat
more food and gain weight. However, even the best study design has limitations. For one thing,
this study was small (just 20 participants), and it only lasted for two
1.10.3 49297 weeks, so we don’t know if the findings apply to the general population over
a lifetime of complex, ever-changing diets. The next steps will be to try to repeat the study in
another group of people to see if the finding holds and to design studies to figure out why
processed foods cause increased caloric intake.
As you evaluate nutrition research, especially observational studies, keep in mind the inherent
challenges of nutrition research and look for randomized controlled trials that can help solve
those challenges. Even for randomized controlled trials, consider their limitations, and know that
one study is never enough to fully answer a question in the complex field of nutrition.
Industry Influence: Follow the Money
Understanding how diet influences health is a pressing need. By some estimates, a suboptimal
diet is the single greatest changeable risk factor contributing to death and disability worldwide,
and in the United States, the cost of diet-related chronic diseases are estimated to be as high
as $1 trillion each year.5 Yet, for all its importance, nutrition science has long suffered from a
lack of government investment, with only about 5 percent of the National Institutes of Health
(NIH) budget, or $1.8 billion, directed towards research on how the foods we eat affect our
health, according to a 2019 investigation by Politico. “In 2018, NIH funding for cancer, which
affects just under 9 percent of the population, was $6.3 billion. Funding for obesity, which
affects about 30 percent of the country, was about $1 billion,” the article noted.6
With so little government funding for nutrition science, who is funding the rest of the studies
that feed the constant news cycle? Many are funded by food companies and industry groups,
either to conduct studies in their own research divisions or in the form of grants given to
university scientists. That’s problematic, because food companies and industry groups have an
inherent bias or conflict of interest. Their primary goal is to promote their products and to sell
more of them—not to advance knowledge of food and health—and this affects how they frame
research questions, design and interpret studies, and report their results.
Marion Nestle, a retired nutrition professor at New York University, has written extensively
about this problem. For a year in 2015-2016, she informally tracked industry-funded studies and
found that 90 percent of the time, their conclusions benefited the industry that funded them. In
another example, a 2013 meta-analysis found that among studies that looked at whether soda
consumption contributed to obesity, those funded by the soda industry were five times more
likely to conclude that it doesn’t contribute to obesity compared to those not funded by the
industry.7 (Consider the processed foods RCT we just discussed. It was funded by the National
Institutes of Health, which doesn’t have a stake in the results. Would you trust the results of a
study of processed foods if it was funded by Nabisco? Or for that matter, the Broccoli Growers
of America? Probably not.)
There’s likely a long history of biased nutrition research influencing dietary advice. For example,
in the 1960s, the sugar industry paid well-respected academic scientists to publish research
concluding that it was fat—not sugar—that was detrimental to heart health.8 (Both too much
fat and too much sugar can negatively affect heart health, but it benefited the sugar industry to
focus the blame on fat.) As recently as 2015, Coca-Cola was funding research meant to
promote lack of physical activity as the main cause of obesity, shifting blame away from dietary
factors, such as drinking soda.9 When food companies drive the narrative coming out of
nutrition research, this can potentially impact public policy.
Media attention has made researchers and policy makers much more aware of the problems
with industry funding and conflicts of interest in nutrition research, and they’re working to solve
them. But regardless, if you see reports of a study that shows that blueberries can block
bladder infections, pistachios can prevent pancreatitis, or cinnamon can cure cancer… well, you
should be skeptical, and always check the funding source. Studies on a single type of food are
almost always industry-funded.
It turns out that there has been a randomized controlled trial of processed foods and weight
gain. It was funded by the National Institutes of Health and published in 2019 in the journal Cell
Metabolism.4 In this study, 20 participants lived in the NIH’s Clinical Center for one month,
where they consumed only processed foods for two weeks and only unprocessed foods for
another two weeks, and they could eat as much or as little as they liked during each of these
periods. The diets were carefully designed by dietitians so that they were matched in calories,
sugar, fat, fiber, and macronutrients, and the exact amounts consumed by the participants
were measured every day (solving the problem of measuring diet complexity and accurately
describing what and how much people eat every day).
The study found that people ate about 500 kilocalories more and gained about a pound per
week when they were eating processed foods. This study design could show causation, not just
correlation, because the other nutritional factors like calories, sugar, fat, fiber, and
macronutrients were held constant, and the diets were tested in the same people, so other
factors such as genetics, sleep, stress, and exercise were constant between the two types of
diets. (This was an example of a crossover randomized controlled trial, in which each subject
serves as their own control, and they completed the processed and unprocessed phases of the
trial in random order.)
Figure 2.6. At left, researchers Kevin Hall and Stephanie Chung talk with one of the processed
foods trial participants at the NIH Clinical Center, an inpatient facility where participants lived
for the duration of the study. At right, an NIH worker prepares meals for participants in the
center’s kitchen. All meals were provided for study participants to carefully control their diet
during the trial.
This study suggested something very important—that food processing causes people to eat
more food and gain weight. However, even the best study design has limitations. For one thing,
this study was small (just 20 participants), and it only lasted for two
1.10.3 49297 weeks, so we don’t know if the findings apply to the general population over
a lifetime of complex, ever-changing diets. The next steps will be to try to repeat the study in
another group of people to see if the finding holds and to design studies to figure out why
processed foods cause increased caloric intake.
As you evaluate nutrition research, especially observational studies, keep in mind the inherent
challenges of nutrition research and look for randomized controlled trials that can help solve
those challenges. Even for randomized controlled trials, consider their limitations, and know that
one study is never enough to fully answer a question in the complex field of nutrition.
Industry Influence: Follow the Money
Understanding how diet influences health is a pressing need. By some estimates, a suboptimal
diet is the single greatest changeable risk factor contributing to death and disability worldwide,
and in the United States, the cost of diet-related chronic diseases are estimated to be as high
as $1 trillion each year.5 Yet, for all its importance, nutrition science has long suffered from a
lack of government investment, with only about 5 percent of the National Institutes of Health
(NIH) budget, or $1.8 billion, directed towards research on how the foods we eat affect our
health, according to a 2019 investigation by Politico. “In 2018, NIH funding for cancer, which
affects just under 9 percent of the population, was $6.3 billion. Funding for obesity, which
affects about 30 percent of the country, was about $1 billion,” the article noted.6
With so little government funding for nutrition science, who is funding the rest of the studies
that feed the constant news cycle? Many are funded by food companies and industry groups,
either to conduct studies in their own research divisions or in the form of grants given to
university scientists. That’s problematic, because food companies and industry groups have an
inherent bias or conflict of interest. Their primary goal is to promote their products and to sell
more of them—not to advance knowledge of food and health—and this affects how they frame
research questions, design and interpret studies, and report their results.
Marion Nestle, a retired nutrition professor at New York University, has written extensively
about this problem. For a year in 2015-2016, she informally tracked industry-funded studies and
found that 90 percent of the time, their conclusions benefited the industry that funded them. In
another example, a 2013 meta-analysis found that among studies that looked at whether soda
consumption contributed to obesity, those funded by the soda industry were five times more
likely to conclude that it doesn’t contribute to obesity compared to those not funded by the
industry.7 (Consider the processed foods RCT we just discussed. It was funded by the National
Institutes of Health, which doesn’t have a stake in the results. Would you trust the results of a
study of processed foods if it was funded by Nabisco? Or for that matter, the Broccoli Growers
of America? Probably not.)
There’s likely a long history of biased nutrition research influencing dietary advice. For example,
in the 1960s, the sugar industry paid well-respected academic scientists to publish research
concluding that it was fat—not sugar—that was detrimental to heart health.8 (Both too much
fat and too much sugar can negatively affect heart health, but it benefited the sugar industry to
focus the blame on fat.) As recently as 2015, Coca-Cola was funding research meant to
promote lack of physical activity as the main cause of obesity, shifting blame away from dietary
factors, such as drinking soda.9 When food companies drive the narrative coming out of
nutrition research, this can potentially impact public policy.
Media attention has made researchers and policy makers much more aware of the problems
with industry funding and conflicts of interest in nutrition research, and they’re working to solve
them. But regardless, if you see reports of a study that shows that blueberries can block
bladder infections, pistachios can prevent pancreatitis, or cinnamon can cure cancer… well, you
should be skeptical, and always check the funding source. Studies on a single type of food are
almost always industry-funded.
It turns out that there has been a randomized controlled trial of processed foods and weight
gain. It was funded by the National Institutes of Health and published in 2019 in the journal Cell
Metabolism.4 In this study, 20 participants lived in the NIH’s Clinical Center for one month,
where they consumed only processed foods for two weeks and only unprocessed foods for
another two weeks, and they could eat as much or as little as they liked during each of these
periods. The diets were carefully designed by dietitians so that they were matched in calories,
sugar, fat, fiber, and macronutrients, and the exact amounts consumed by the participants
were measured every day (solving the problem of measuring diet complexity and accurately
describing what and how much people eat every day).
The study found that people ate about 500 kilocalories more and gained about a pound per
week when they were eating processed foods. This study design could show causation, not just
correlation, because the other nutritional factors like calories, sugar, fat, fiber, and
macronutrients were held constant, and the diets were tested in the same people, so other
factors such as genetics, sleep, stress, and exercise were constant between the two types of
diets. (This was an example of a crossover randomized controlled trial, in which each subject
serves as their own control, and they completed the processed and unprocessed phases of the
trial in random order.)
Figure 2.6. At left, researchers Kevin Hall and Stephanie Chung talk with one of the processed
foods trial participants at the NIH Clinical Center, an inpatient facility where participants lived
for the duration of the study. At right, an NIH worker prepares meals for participants in the
center’s kitchen. All meals were provided for study participants to carefully control their diet
during the trial.
This study suggested something very important—that food processing causes people to eat
more food and gain weight. However, even the best study design has limitations. For one thing,
this study was small (just 20 participants), and it only lasted for two
1.10.3 49297 weeks, so we don’t know if the findings apply to the general population over
a lifetime of complex, ever-changing diets. The next steps will be to try to repeat the study in
another group of people to see if the finding holds and to design studies to figure out why
processed foods cause increased caloric intake.
As you evaluate nutrition research, especially observational studies, keep in mind the inherent
challenges of nutrition research and look for randomized controlled trials that can help solve
those challenges. Even for randomized controlled trials, consider their limitations, and know that
one study is never enough to fully answer a question in the complex field of nutrition.
Industry Influence: Follow the Money
Understanding how diet influences health is a pressing need. By some estimates, a suboptimal
diet is the single greatest changeable risk factor contributing to death and disability worldwide,
and in the United States, the cost of diet-related chronic diseases are estimated to be as high
as $1 trillion each year.5 Yet, for all its importance, nutrition science has long suffered from a
lack of government investment, with only about 5 percent of the National Institutes of Health
(NIH) budget, or $1.8 billion, directed towards research on how the foods we eat affect our
health, according to a 2019 investigation by Politico. “In 2018, NIH funding for cancer, which
affects just under 9 percent of the population, was $6.3 billion. Funding for obesity, which
affects about 30 percent of the country, was about $1 billion,” the article noted.6
With so little government funding for nutrition science, who is funding the rest of the studies
that feed the constant news cycle? Many are funded by food companies and industry groups,
either to conduct studies in their own research divisions or in the form of grants given to
university scientists. That’s problematic, because food companies and industry groups have an
inherent bias or conflict of interest. Their primary goal is to promote their products and to sell
more of them—not to advance knowledge of food and health—and this affects how they frame
research questions, design and interpret studies, and report their results.
Marion Nestle, a retired nutrition professor at New York University, has written extensively
about this problem. For a year in 2015-2016, she informally tracked industry-funded studies and
found that 90 percent of the time, their conclusions benefited the industry that funded them. In
another example, a 2013 meta-analysis found that among studies that looked at whether soda
consumption contributed to obesity, those funded by the soda industry were five times more
likely to conclude that it doesn’t contribute to obesity compared to those not funded by the
industry.7 (Consider the processed foods RCT we just discussed. It was funded by the National
Institutes of Health, which doesn’t have a stake in the results. Would you trust the results of a
study of processed foods if it was funded by Nabisco? Or for that matter, the Broccoli Growers
of America? Probably not.)
There’s likely a long history of biased nutrition research influencing dietary advice. For example,
in the 1960s, the sugar industry paid well-respected academic scientists to publish research
concluding that it was fat—not sugar—that was detrimental to heart health.8 (Both too much
fat and too much sugar can negatively affect heart health, but it benefited the sugar industry to
focus the blame on fat.) As recently as 2015, Coca-Cola was funding research meant to
promote lack of physical activity as the main cause of obesity, shifting blame away from dietary
factors, such as drinking soda.9 When food companies drive the narrative coming out of
nutrition research, this can potentially impact public policy.
Media attention has made researchers and policy makers much more aware of the problems
with industry funding and conflicts of interest in nutrition research, and they’re working to solve
them. But regardless, if you see reports of a study that shows that blueberries can block
bladder infections, pistachios can prevent pancreatitis, or cinnamon can cure cancer… well, you
should be skeptical, and always check the funding source. Studies on a single type of food are
almost always industry-funded.
It turns out that there has been a randomized controlled trial of processed foods and weight
gain. It was funded by the National Institutes of Health and published in 2019 in the journal Cell
Metabolism.4 In this study, 20 participants lived in the NIH’s Clinical Center for one month,
where they consumed only processed foods for two weeks and only unprocessed foods for
another two weeks, and they could eat as much or as little as they liked during each of these
periods. The diets were carefully designed by dietitians so that they were matched in calories,
sugar, fat, fiber, and macronutrients, and the exact amounts consumed by the participants
were measured every day (solving the problem of measuring diet complexity and accurately
describing what and how much people eat every day).
The study found that people ate about 500 kilocalories more and gained about a pound per
week when they were eating processed foods. This study design could show causation, not just
correlation, because the other nutritional factors like calories, sugar, fat, fiber, and
macronutrients were held constant, and the diets were tested in the same people, so other
factors such as genetics, sleep, stress, and exercise were constant between the two types of
diets. (This was an example of a crossover randomized controlled trial, in which each subject
serves as their own control, and they completed the processed and unprocessed phases of the
trial in random order.)
Figure 2.6. At left, researchers Kevin Hall and Stephanie Chung talk with one of the processed
foods trial participants at the NIH Clinical Center, an inpatient facility where participants lived
for the duration of the study. At right, an NIH worker prepares meals for participants in the
center’s kitchen. All meals were provided for study participants to carefully control their diet
during the trial.
This study suggested something very important—that food processing causes people to eat
more food and gain weight. However, even the best study design has limitations. For one thing,
this study was small (just 20 participants), and it only lasted for two
1.10.3 49297 weeks, so we don’t know if the findings apply to the general population over
a lifetime of complex, ever-changing diets. The next steps will be to try to repeat the study in
another group of people to see if the finding holds and to design studies to figure out why
processed foods cause increased caloric intake.
As you evaluate nutrition research, especially observational studies, keep in mind the inherent
challenges of nutrition research and look for randomized controlled trials that can help solve
those challenges. Even for randomized controlled trials, consider their limitations, and know that
one study is never enough to fully answer a question in the complex field of nutrition.
Industry Influence: Follow the Money
Understanding how diet influences health is a pressing need. By some estimates, a suboptimal
diet is the single greatest changeable risk factor contributing to death and disability worldwide,
and in the United States, the cost of diet-related chronic diseases are estimated to be as high
as $1 trillion each year.5 Yet, for all its importance, nutrition science has long suffered from a
lack of government investment, with only about 5 percent of the National Institutes of Health
(NIH) budget, or $1.8 billion, directed towards research on how the foods we eat affect our
health, according to a 2019 investigation by Politico. “In 2018, NIH funding for cancer, which
affects just under 9 percent of the population, was $6.3 billion. Funding for obesity, which
affects about 30 percent of the country, was about $1 billion,” the article noted.6
With so little government funding for nutrition science, who is funding the rest of the studies
that feed the constant news cycle? Many are funded by food companies and industry groups,
either to conduct studies in their own research divisions or in the form of grants given to
university scientists. That’s problematic, because food companies and industry groups have an
inherent bias or conflict of interest. Their primary goal is to promote their products and to sell
more of them—not to advance knowledge of food and health—and this affects how they frame
research questions, design and interpret studies, and report their results.
Marion Nestle, a retired nutrition professor at New York University, has written extensively
about this problem. For a year in 2015-2016, she informally tracked industry-funded studies and
found that 90 percent of the time, their conclusions benefited the industry that funded them. In
another example, a 2013 meta-analysis found that among studies that looked at whether soda
consumption contributed to obesity, those funded by the soda industry were five times more
likely to conclude that it doesn’t contribute to obesity compared to those not funded by the
industry.7 (Consider the processed foods RCT we just discussed. It was funded by the National
Institutes of Health, which doesn’t have a stake in the results. Would you trust the results of a
study of processed foods if it was funded by Nabisco? Or for that matter, the Broccoli Growers
of America? Probably not.)
There’s likely a long history of biased nutrition research influencing dietary advice. For example,
in the 1960s, the sugar industry paid well-respected academic scientists to publish research
concluding that it was fat—not sugar—that was detrimental to heart health.8 (Both too much
fat and too much sugar can negatively affect heart health, but it benefited the sugar industry to
focus the blame on fat.) As recently as 2015, Coca-Cola was funding research meant to
promote lack of physical activity as the main cause of obesity, shifting blame away from dietary
factors, such as drinking soda.9 When food companies drive the narrative coming out of
nutrition research, this can potentially impact public policy.
Media attention has made researchers and policy makers much more aware of the problems
with industry funding and conflicts of interest in nutrition research, and they’re working to solve
them. But regardless, if you see reports of a study that shows that blueberries can block
bladder infections, pistachios can prevent pancreatitis, or cinnamon can cure cancer… well, you
should be skeptical, and always check the funding source. Studies on a single type of food are
almost always industry-funded.
It turns out that there has been a randomized controlled trial of processed foods and weight
gain. It was funded by the National Institutes of Health and published in 2019 in the journal Cell
Metabolism.4 In this study, 20 participants lived in the NIH’s Clinical Center for one month,
where they consumed only processed foods for two weeks and only unprocessed foods for
another two weeks, and they could eat as much or as little as they liked during each of these
periods. The diets were carefully designed by dietitians so that they were matched in calories,
sugar, fat, fiber, and macronutrients, and the exact amounts consumed by the participants
were measured every day (solving the problem of measuring diet complexity and accurately
describing what and how much people eat every day).
The study found that people ate about 500 kilocalories more and gained about a pound per
week when they were eating processed foods. This study design could show causation, not just
correlation, because the other nutritional factors like calories, sugar, fat, fiber, and
macronutrients were held constant, and the diets were tested in the same people, so other
factors such as genetics, sleep, stress, and exercise were constant between the two types of
diets. (This was an example of a crossover randomized controlled trial, in which each subject
serves as their own control, and they completed the processed and unprocessed phases of the
trial in random order.)
Figure 2.6. At left, researchers Kevin Hall and Stephanie Chung talk with one of the processed
foods trial participants at the NIH Clinical Center, an inpatient facility where participants lived
for the duration of the study. At right, an NIH worker prepares meals for participants in the
center’s kitchen. All meals were provided for study participants to carefully control their diet
during the trial.
This study suggested something very important—that food processing causes people to eat
more food and gain weight. However, even the best study design has limitations. For one thing,
this study was small (just 20 participants), and it only lasted for two
1.10.3 49297 weeks, so we don’t know if the findings apply to the general population over
a lifetime of complex, ever-changing diets. The next steps will be to try to repeat the study in
another group of people to see if the finding holds and to design studies to figure out why
processed foods cause increased caloric intake.
As you evaluate nutrition research, especially observational studies, keep in mind the inherent
challenges of nutrition research and look for randomized controlled trials that can help solve
those challenges. Even for randomized controlled trials, consider their limitations, and know that
one study is never enough to fully answer a question in the complex field of nutrition.
Industry Influence: Follow the Money
Understanding how diet influences health is a pressing need. By some estimates, a suboptimal
diet is the single greatest changeable risk factor contributing to death and disability worldwide,
and in the United States, the cost of diet-related chronic diseases are estimated to be as high
as $1 trillion each year.5 Yet, for all its importance, nutrition science has long suffered from a
lack of government investment, with only about 5 percent of the National Institutes of Health
(NIH) budget, or $1.8 billion, directed towards research on how the foods we eat affect our
health, according to a 2019 investigation by Politico. “In 2018, NIH funding for cancer, which
affects just under 9 percent of the population, was $6.3 billion. Funding for obesity, which
affects about 30 percent of the country, was about $1 billion,” the article noted.6
With so little government funding for nutrition science, who is funding the rest of the studies
that feed the constant news cycle? Many are funded by food companies and industry groups,
either to conduct studies in their own research divisions or in the form of grants given to
university scientists. That’s problematic, because food companies and industry groups have an
inherent bias or conflict of interest. Their primary goal is to promote their products and to sell
more of them—not to advance knowledge of food and health—and this affects how they frame
research questions, design and interpret studies, and report their results.
Marion Nestle, a retired nutrition professor at New York University, has written extensively
about this problem. For a year in 2015-2016, she informally tracked industry-funded studies and
found that 90 percent of the time, their conclusions benefited the industry that funded them. In
another example, a 2013 meta-analysis found that among studies that looked at whether soda
consumption contributed to obesity, those funded by the soda industry were five times more
likely to conclude that it doesn’t contribute to obesity compared to those not funded by the
industry.7 (Consider the processed foods RCT we just discussed. It was funded by the National
Institutes of Health, which doesn’t have a stake in the results. Would you trust the results of a
study of processed foods if it was funded by Nabisco? Or for that matter, the Broccoli Growers
of America? Probably not.)
There’s likely a long history of biased nutrition research influencing dietary advice. For example,
in the 1960s, the sugar industry paid well-respected academic scientists to publish research
concluding that it was fat—not sugar—that was detrimental to heart health.8 (Both too much
fat and too much sugar can negatively affect heart health, but it benefited the sugar industry to
focus the blame on fat.) As recently as 2015, Coca-Cola was funding research meant to
promote lack of physical activity as the main cause of obesity, shifting blame away from dietary
factors, such as drinking soda.9 When food companies drive the narrative coming out of
nutrition research, this can potentially impact public policy.
Media attention has made researchers and policy makers much more aware of the problems
with industry funding and conflicts of interest in nutrition research, and they’re working to solve
them. But regardless, if you see reports of a study that shows that blueberries can block
bladder infections, pistachios can prevent pancreatitis, or cinnamon can cure cancer… well, you
should be skeptical, and always check the funding source. Studies on a single type of food are
almost always industry-funded.
It turns out that there has been a randomized controlled trial of processed foods and weight
gain. It was funded by the National Institutes of Health and published in 2019 in the journal Cell
Metabolism.4 In this study, 20 participants lived in the NIH’s Clinical Center for one month,
where they consumed only processed foods for two weeks and only unprocessed foods for
another two weeks, and they could eat as much or as little as they liked during each of these
periods. The diets were carefully designed by dietitians so that they were matched in calories,
sugar, fat, fiber, and macronutrients, and the exact amounts consumed by the participants
were measured every day (solving the problem of measuring diet complexity and accurately
describing what and how much people eat every day).
The study found that people ate about 500 kilocalories more and gained about a pound per
week when they were eating processed foods. This study design could show causation, not just
correlation, because the other nutritional factors like calories, sugar, fat, fiber, and
macronutrients were held constant, and the diets were tested in the same people, so other
factors such as genetics, sleep, stress, and exercise were constant between the two types of
diets. (This was an example of a crossover randomized controlled trial, in which each subject
serves as their own control, and they completed the processed and unprocessed phases of the
trial in random order.)
Figure 2.6. At left, researchers Kevin Hall and Stephanie Chung talk with one of the processed
foods trial participants at the NIH Clinical Center, an inpatient facility where participants lived
for the duration of the study. At right, an NIH worker prepares meals for participants in the
center’s kitchen. All meals were provided for study participants to carefully control their diet
during the trial.
This study suggested something very important—that food processing causes people to eat
more food and gain weight. However, even the best study design has limitations. For one thing,
this study was small (just 20 participants), and it only lasted for two
1.10.3 49297 weeks, so we don’t know if the findings apply to the general population over
a lifetime of complex, ever-changing diets. The next steps will be to try to repeat the study in
another group of people to see if the finding holds and to design studies to figure out why
processed foods cause increased caloric intake.
As you evaluate nutrition research, especially observational studies, keep in mind the inherent
challenges of nutrition research and look for randomized controlled trials that can help solve
those challenges. Even for randomized controlled trials, consider their limitations, and know that
one study is never enough to fully answer a question in the complex field of nutrition.
Industry Influence: Follow the Money
Understanding how diet influences health is a pressing need. By some estimates, a suboptimal
diet is the single greatest changeable risk factor contributing to death and disability worldwide,
and in the United States, the cost of diet-related chronic diseases are estimated to be as high
as $1 trillion each year.5 Yet, for all its importance, nutrition science has long suffered from a
lack of government investment, with only about 5 percent of the National Institutes of Health
(NIH) budget, or $1.8 billion, directed towards research on how the foods we eat affect our
health, according to a 2019 investigation by Politico. “In 2018, NIH funding for cancer, which
affects just under 9 percent of the population, was $6.3 billion. Funding for obesity, which
affects about 30 percent of the country, was about $1 billion,” the article noted.6
With so little government funding for nutrition science, who is funding the rest of the studies
that feed the constant news cycle? Many are funded by food companies and industry groups,
either to conduct studies in their own research divisions or in the form of grants given to
university scientists. That’s problematic, because food companies and industry groups have an
inherent bias or conflict of interest. Their primary goal is to promote their products and to sell
more of them—not to advance knowledge of food and health—and this affects how they frame
research questions, design and interpret studies, and report their results.
Marion Nestle, a retired nutrition professor at New York University, has written extensively
about this problem. For a year in 2015-2016, she informally tracked industry-funded studies and
found that 90 percent of the time, their conclusions benefited the industry that funded them. In
another example, a 2013 meta-analysis found that among studies that looked at whether soda
consumption contributed to obesity, those funded by the soda industry were five times more
likely to conclude that it doesn’t contribute to obesity compared to those not funded by the
industry.7 (Consider the processed foods RCT we just discussed. It was funded by the National
Institutes of Health, which doesn’t have a stake in the results. Would you trust the results of a
study of processed foods if it was funded by Nabisco? Or for that matter, the Broccoli Growers
of America? Probably not.)
There’s likely a long history of biased nutrition research influencing dietary advice. For example,
in the 1960s, the sugar industry paid well-respected academic scientists to publish research
concluding that it was fat—not sugar—that was detrimental to heart health.8 (Both too much
fat and too much sugar can negatively affect heart health, but it benefited the sugar industry to
focus the blame on fat.) As recently as 2015, Coca-Cola was funding research meant to
promote lack of physical activity as the main cause of obesity, shifting blame away from dietary
factors, such as drinking soda.9 When food companies drive the narrative coming out of
nutrition research, this can potentially impact public policy.
Media attention has made researchers and policy makers much more aware of the problems
with industry funding and conflicts of interest in nutrition research, and they’re working to solve
them. But regardless, if you see reports of a study that shows that blueberries can block
bladder infections, pistachios can prevent pancreatitis, or cinnamon can cure cancer… well, you
should be skeptical, and always check the funding source. Studies on a single type of food are
almost always industry-funded.
It turns out that there has been a randomized controlled trial of processed foods and weight
gain. It was funded by the National Institutes of Health and published in 2019 in the journal Cell
Metabolism.4 In this study, 20 participants lived in the NIH’s Clinical Center for one month,
where they consumed only processed foods for two weeks and only unprocessed foods for
another two weeks, and they could eat as much or as little as they liked during each of these
periods. The diets were carefully designed by dietitians so that they were matched in calories,
sugar, fat, fiber, and macronutrients, and the exact amounts consumed by the participants
were measured every day (solving the problem of measuring diet complexity and accurately
describing what and how much people eat every day).
The study found that people ate about 500 kilocalories more and gained about a pound per
week when they were eating processed foods. This study design could show causation, not just
correlation, because the other nutritional factors like calories, sugar, fat, fiber, and
macronutrients were held constant, and the diets were tested in the same people, so other
factors such as genetics, sleep, stress, and exercise were constant between the two types of
diets. (This was an example of a crossover randomized controlled trial, in which each subject
serves as their own control, and they completed the processed and unprocessed phases of the
trial in random order.)
Figure 2.6. At left, researchers Kevin Hall and Stephanie Chung talk with one of the processed
foods trial participants at the NIH Clinical Center, an inpatient facility where participants lived
for the duration of the study. At right, an NIH worker prepares meals for participants in the
center’s kitchen. All meals were provided for study participants to carefully control their diet
during the trial.
This study suggested something very important—that food processing causes people to eat
more food and gain weight. However, even the best study design has limitations. For one thing,
this study was small (just 20 participants), and it only lasted for two
1.10.3 49297 weeks, so we don’t know if the findings apply to the general population over
a lifetime of complex, ever-changing diets. The next steps will be to try to repeat the study in
another group of people to see if the finding holds and to design studies to figure out why
processed foods cause increased caloric intake.
As you evaluate nutrition research, especially observational studies, keep in mind the inherent
challenges of nutrition research and look for randomized controlled trials that can help solve
those challenges. Even for randomized controlled trials, consider their limitations, and know that
one study is never enough to fully answer a question in the complex field of nutrition.
Industry Influence: Follow the Money
Understanding how diet influences health is a pressing need. By some estimates, a suboptimal
diet is the single greatest changeable risk factor contributing to death and disability worldwide,
and in the United States, the cost of diet-related chronic diseases are estimated to be as high
as $1 trillion each year.5 Yet, for all its importance, nutrition science has long suffered from a
lack of government investment, with only about 5 percent of the National Institutes of Health
(NIH) budget, or $1.8 billion, directed towards research on how the foods we eat affect our
health, according to a 2019 investigation by Politico. “In 2018, NIH funding for cancer, which
affects just under 9 percent of the population, was $6.3 billion. Funding for obesity, which
affects about 30 percent of the country, was about $1 billion,” the article noted.6
With so little government funding for nutrition science, who is funding the rest of the studies
that feed the constant news cycle? Many are funded by food companies and industry groups,
either to conduct studies in their own research divisions or in the form of grants given to
university scientists. That’s problematic, because food companies and industry groups have an
inherent bias or conflict of interest. Their primary goal is to promote their products and to sell
more of them—not to advance knowledge of food and health—and this affects how they frame
research questions, design and interpret studies, and report their results.
Marion Nestle, a retired nutrition professor at New York University, has written extensively
about this problem. For a year in 2015-2016, she informally tracked industry-funded studies and
found that 90 percent of the time, their conclusions benefited the industry that funded them. In
another example, a 2013 meta-analysis found that among studies that looked at whether soda
consumption contributed to obesity, those funded by the soda industry were five times more
likely to conclude that it doesn’t contribute to obesity compared to those not funded by the
industry.7 (Consider the processed foods RCT we just discussed. It was funded by the National
Institutes of Health, which doesn’t have a stake in the results. Would you trust the results of a
study of processed foods if it was funded by Nabisco? Or for that matter, the Broccoli Growers
of America? Probably not.)
There’s likely a long history of biased nutrition research influencing dietary advice. For example,
in the 1960s, the sugar industry paid well-respected academic scientists to publish research
concluding that it was fat—not sugar—that was detrimental to heart health.8 (Both too much
fat and too much sugar can negatively affect heart health, but it benefited the sugar industry to
focus the blame on fat.) As recently as 2015, Coca-Cola was funding research meant to
promote lack of physical activity as the main cause of obesity, shifting blame away from dietary
factors, such as drinking soda.9 When food companies drive the narrative coming out of
nutrition research, this can potentially impact public policy.
Media attention has made researchers and policy makers much more aware of the problems
with industry funding and conflicts of interest in nutrition research, and they’re working to solve
them. But regardless, if you see reports of a study that shows that blueberries can block
bladder infections, pistachios can prevent pancreatitis, or cinnamon can cure cancer… well, you
should be skeptical, and always check the funding source. Studies on a single type of food are
almost always industry-funded.
It turns out that there has been a randomized controlled trial of processed foods and weight
gain. It was funded by the National Institutes of Health and published in 2019 in the journal Cell
Metabolism.4 In this study, 20 participants lived in the NIH’s Clinical Center for one month,
where they consumed only processed foods for two weeks and only unprocessed foods for
another two weeks, and they could eat as much or as little as they liked during each of these
periods. The diets were carefully designed by dietitians so that they were matched in calories,
sugar, fat, fiber, and macronutrients, and the exact amounts consumed by the participants
were measured every day (solving the problem of measuring diet complexity and accurately
describing what and how much people eat every day).
The study found that people ate about 500 kilocalories more and gained about a pound per
week when they were eating processed foods. This study design could show causation, not just
correlation, because the other nutritional factors like calories, sugar, fat, fiber, and
macronutrients were held constant, and the diets were tested in the same people, so other
factors such as genetics, sleep, stress, and exercise were constant between the two types of
diets. (This was an example of a crossover randomized controlled trial, in which each subject
serves as their own control, and they completed the processed and unprocessed phases of the
trial in random order.)
Figure 2.6. At left, researchers Kevin Hall and Stephanie Chung talk with one of the processed
foods trial participants at the NIH Clinical Center, an inpatient facility where participants lived
for the duration of the study. At right, an NIH worker prepares meals for participants in the
center’s kitchen. All meals were provided for study participants to carefully control their diet
during the trial.
This study suggested something very important—that food processing causes people to eat
more food and gain weight. However, even the best study design has limitations. For one thing,
this study was small (just 20 participants), and it only lasted for two
1.10.3 49297 weeks, so we don’t know if the findings apply to the general population over
a lifetime of complex, ever-changing diets. The next steps will be to try to repeat the study in
another group of people to see if the finding holds and to design studies to figure out why
processed foods cause increased caloric intake.
As you evaluate nutrition research, especially observational studies, keep in mind the inherent
challenges of nutrition research and look for randomized controlled trials that can help solve
those challenges. Even for randomized controlled trials, consider their limitations, and know that
one study is never enough to fully answer a question in the complex field of nutrition.
Industry Influence: Follow the Money
Understanding how diet influences health is a pressing need. By some estimates, a suboptimal
diet is the single greatest changeable risk factor contributing to death and disability worldwide,
and in the United States, the cost of diet-related chronic diseases are estimated to be as high
as $1 trillion each year.5 Yet, for all its importance, nutrition science has long suffered from a
lack of government investment, with only about 5 percent of the National Institutes of Health
(NIH) budget, or $1.8 billion, directed towards research on how the foods we eat affect our
health, according to a 2019 investigation by Politico. “In 2018, NIH funding for cancer, which
affects just under 9 percent of the population, was $6.3 billion. Funding for obesity, which
affects about 30 percent of the country, was about $1 billion,” the article noted.6
With so little government funding for nutrition science, who is funding the rest of the studies
that feed the constant news cycle? Many are funded by food companies and industry groups,
either to conduct studies in their own research divisions or in the form of grants given to
university scientists. That’s problematic, because food companies and industry groups have an
inherent bias or conflict of interest. Their primary goal is to promote their products and to sell
more of them—not to advance knowledge of food and health—and this affects how they frame
research questions, design and interpret studies, and report their results.
Marion Nestle, a retired nutrition professor at New York University, has written extensively
about this problem. For a year in 2015-2016, she informally tracked industry-funded studies and
found that 90 percent of the time, their conclusions benefited the industry that funded them. In
another example, a 2013 meta-analysis found that among studies that looked at whether soda
consumption contributed to obesity, those funded by the soda industry were five times more
likely to conclude that it doesn’t contribute to obesity compared to those not funded by the
industry.7 (Consider the processed foods RCT we just discussed. It was funded by the National
Institutes of Health, which doesn’t have a stake in the results. Would you trust the results of a
study of processed foods if it was funded by Nabisco? Or for that matter, the Broccoli Growers
of America? Probably not.)
There’s likely a long history of biased nutrition research influencing dietary advice. For example,
in the 1960s, the sugar industry paid well-respected academic scientists to publish research
concluding that it was fat—not sugar—that was detrimental to heart health.8 (Both too much
fat and too much sugar can negatively affect heart health, but it benefited the sugar industry to
focus the blame on fat.) As recently as 2015, Coca-Cola was funding research meant to
promote lack of physical activity as the main cause of obesity, shifting blame away from dietary
factors, such as drinking soda.9 When food companies drive the narrative coming out of
nutrition research, this can potentially impact public policy.
Media attention has made researchers and policy makers much more aware of the problems
with industry funding and conflicts of interest in nutrition research, and they’re working to solve
them. But regardless, if you see reports of a study that shows that blueberries can block
bladder infections, pistachios can prevent pancreatitis, or cinnamon can cure cancer… well, you
should be skeptical, and always check the funding source. Studies on a single type of food are
almost always industry-funded.
It turns out that there has been a randomized controlled trial of processed foods and weight
gain. It was funded by the National Institutes of Health and published in 2019 in the journal Cell
Metabolism.4 In this study, 20 participants lived in the NIH’s Clinical Center for one month,
where they consumed only processed foods for two weeks and only unprocessed foods for
another two weeks, and they could eat as much or as little as they liked during each of these
periods. The diets were carefully designed by dietitians so that they were matched in calories,
sugar, fat, fiber, and macronutrients, and the exact amounts consumed by the participants
were measured every day (solving the problem of measuring diet complexity and accurately
describing what and how much people eat every day).
The study found that people ate about 500 kilocalories more and gained about a pound per
week when they were eating processed foods. This study design could show causation, not just
correlation, because the other nutritional factors like calories, sugar, fat, fiber, and
macronutrients were held constant, and the diets were tested in the same people, so other
factors such as genetics, sleep, stress, and exercise were constant between the two types of
diets. (This was an example of a crossover randomized controlled trial, in which each subject
serves as their own control, and they completed the processed and unprocessed phases of the
trial in random order.)
Figure 2.6. At left, researchers Kevin Hall and Stephanie Chung talk with one of the processed
foods trial participants at the NIH Clinical Center, an inpatient facility where participants lived
for the duration of the study. At right, an NIH worker prepares meals for participants in the
center’s kitchen. All meals were provided for study participants to carefully control their diet
during the trial.
This study suggested something very important—that food processing causes people to eat
more food and gain weight. However, even the best study design has limitations. For one thing,
this study was small (just 20 participants), and it only lasted for two
1.10.3 49297 weeks, so we don’t know if the findings apply to the general population over
a lifetime of complex, ever-changing diets. The next steps will be to try to repeat the study in
another group of people to see if the finding holds and to design studies to figure out why
processed foods cause increased caloric intake.
As you evaluate nutrition research, especially observational studies, keep in mind the inherent
challenges of nutrition research and look for randomized controlled trials that can help solve
those challenges. Even for randomized controlled trials, consider their limitations, and know that
one study is never enough to fully answer a question in the complex field of nutrition.
Industry Influence: Follow the Money
Understanding how diet influences health is a pressing need. By some estimates, a suboptimal
diet is the single greatest changeable risk factor contributing to death and disability worldwide,
and in the United States, the cost of diet-related chronic diseases are estimated to be as high
as $1 trillion each year.5 Yet, for all its importance, nutrition science has long suffered from a
lack of government investment, with only about 5 percent of the National Institutes of Health
(NIH) budget, or $1.8 billion, directed towards research on how the foods we eat affect our
health, according to a 2019 investigation by Politico. “In 2018, NIH funding for cancer, which
affects just under 9 percent of the population, was $6.3 billion. Funding for obesity, which
affects about 30 percent of the country, was about $1 billion,” the article noted.6
With so little government funding for nutrition science, who is funding the rest of the studies
that feed the constant news cycle? Many are funded by food companies and industry groups,
either to conduct studies in their own research divisions or in the form of grants given to
university scientists. That’s problematic, because food companies and industry groups have an
inherent bias or conflict of interest. Their primary goal is to promote their products and to sell
more of them—not to advance knowledge of food and health—and this affects how they frame
research questions, design and interpret studies, and report their results.
Marion Nestle, a retired nutrition professor at New York University, has written extensively
about this problem. For a year in 2015-2016, she informally tracked industry-funded studies and
found that 90 percent of the time, their conclusions benefited the industry that funded them. In
another example, a 2013 meta-analysis found that among studies that looked at whether soda
consumption contributed to obesity, those funded by the soda industry were five times more
likely to conclude that it doesn’t contribute to obesity compared to those not funded by the
industry.7 (Consider the processed foods RCT we just discussed. It was funded by the National
Institutes of Health, which doesn’t have a stake in the results. Would you trust the results of a
study of processed foods if it was funded by Nabisco? Or for that matter, the Broccoli Growers
of America? Probably not.)
There’s likely a long history of biased nutrition research influencing dietary advice. For example,
in the 1960s, the sugar industry paid well-respected academic scientists to publish research
concluding that it was fat—not sugar—that was detrimental to heart health.8 (Both too much
fat and too much sugar can negatively affect heart health, but it benefited the sugar industry to
focus the blame on fat.) As recently as 2015, Coca-Cola was funding research meant to
promote lack of physical activity as the main cause of obesity, shifting blame away from dietary
factors, such as drinking soda.9 When food companies drive the narrative coming out of
nutrition research, this can potentially impact public policy.
Media attention has made researchers and policy makers much more aware of the problems
with industry funding and conflicts of interest in nutrition research, and they’re working to solve
them. But regardless, if you see reports of a study that shows that blueberries can block
bladder infections, pistachios can prevent pancreatitis, or cinnamon can cure cancer… well, you
should be skeptical, and always check the funding source. Studies on a single type of food are
almost always industry-funded.
It turns out that there has been a randomized controlled trial of processed foods and weight
gain. It was funded by the National Institutes of Health and published in 2019 in the journal Cell
Metabolism.4 In this study, 20 participants lived in the NIH’s Clinical Center for one month,
where they consumed only processed foods for two weeks and only unprocessed foods for
another two weeks, and they could eat as much or as little as they liked during each of these
periods. The diets were carefully designed by dietitians so that they were matched in calories,
sugar, fat, fiber, and macronutrients, and the exact amounts consumed by the participants
were measured every day (solving the problem of measuring diet complexity and accurately
describing what and how much people eat every day).
The study found that people ate about 500 kilocalories more and gained about a pound per
week when they were eating processed foods. This study design could show causation, not just
correlation, because the other nutritional factors like calories, sugar, fat, fiber, and
macronutrients were held constant, and the diets were tested in the same people, so other
factors such as genetics, sleep, stress, and exercise were constant between the two types of
diets. (This was an example of a crossover randomized controlled trial, in which each subject
serves as their own control, and they completed the processed and unprocessed phases of the
trial in random order.)
Figure 2.6. At left, researchers Kevin Hall and Stephanie Chung talk with one of the processed
foods trial participants at the NIH Clinical Center, an inpatient facility where participants lived
for the duration of the study. At right, an NIH worker prepares meals for participants in the
center’s kitchen. All meals were provided for study participants to carefully control their diet
during the trial.
This study suggested something very important—that food processing causes people to eat
more food and gain weight. However, even the best study design has limitations. For one thing,
this study was small (just 20 participants), and it only lasted for two
1.10.3 49297 weeks, so we don’t know if the findings apply to the general population over
a lifetime of complex, ever-changing diets. The next steps will be to try to repeat the study in
another group of people to see if the finding holds and to design studies to figure out why
processed foods cause increased caloric intake.
As you evaluate nutrition research, especially observational studies, keep in mind the inherent
challenges of nutrition research and look for randomized controlled trials that can help solve
those challenges. Even for randomized controlled trials, consider their limitations, and know that
one study is never enough to fully answer a question in the complex field of nutrition.
Industry Influence: Follow the Money
Understanding how diet influences health is a pressing need. By some estimates, a suboptimal
diet is the single greatest changeable risk factor contributing to death and disability worldwide,
and in the United States, the cost of diet-related chronic diseases are estimated to be as high
as $1 trillion each year.5 Yet, for all its importance, nutrition science has long suffered from a
lack of government investment, with only about 5 percent of the National Institutes of Health
(NIH) budget, or $1.8 billion, directed towards research on how the foods we eat affect our
health, according to a 2019 investigation by Politico. “In 2018, NIH funding for cancer, which
affects just under 9 percent of the population, was $6.3 billion. Funding for obesity, which
affects about 30 percent of the country, was about $1 billion,” the article noted.6
With so little government funding for nutrition science, who is funding the rest of the studies
that feed the constant news cycle? Many are funded by food companies and industry groups,
either to conduct studies in their own research divisions or in the form of grants given to
university scientists. That’s problematic, because food companies and industry groups have an
inherent bias or conflict of interest. Their primary goal is to promote their products and to sell
more of them—not to advance knowledge of food and health—and this affects how they frame
research questions, design and interpret studies, and report their results.
Marion Nestle, a retired nutrition professor at New York University, has written extensively
about this problem. For a year in 2015-2016, she informally tracked industry-funded studies and
found that 90 percent of the time, their conclusions benefited the industry that funded them. In
another example, a 2013 meta-analysis found that among studies that looked at whether soda
consumption contributed to obesity, those funded by the soda industry were five times more
likely to conclude that it doesn’t contribute to obesity compared to those not funded by the
industry.7 (Consider the processed foods RCT we just discussed. It was funded by the National
Institutes of Health, which doesn’t have a stake in the results. Would you trust the results of a
study of processed foods if it was funded by Nabisco? Or for that matter, the Broccoli Growers
of America? Probably not.)
There’s likely a long history of biased nutrition research influencing dietary advice. For example,
in the 1960s, the sugar industry paid well-respected academic scientists to publish research
concluding that it was fat—not sugar—that was detrimental to heart health.8 (Both too much
fat and too much sugar can negatively affect heart health, but it benefited the sugar industry to
focus the blame on fat.) As recently as 2015, Coca-Cola was funding research meant to
promote lack of physical activity as the main cause of obesity, shifting blame away from dietary
factors, such as drinking soda.9 When food companies drive the narrative coming out of
nutrition research, this can potentially impact public policy.
Media attention has made researchers and policy makers much more aware of the problems
with industry funding and conflicts of interest in nutrition research, and they’re working to solve
them. But regardless, if you see reports of a study that shows that blueberries can block
bladder infections, pistachios can prevent pancreatitis, or cinnamon can cure cancer… well, you
should be skeptical, and always check the funding source. Studies on a single type of food are
almost always industry-funded.
It turns out that there has been a randomized controlled trial of processed foods and weight
gain. It was funded by the National Institutes of Health and published in 2019 in the journal Cell
Metabolism.4 In this study, 20 participants lived in the NIH’s Clinical Center for one month,
where they consumed only processed foods for two weeks and only unprocessed foods for
another two weeks, and they could eat as much or as little as they liked during each of these
periods. The diets were carefully designed by dietitians so that they were matched in calories,
sugar, fat, fiber, and macronutrients, and the exact amounts consumed by the participants
were measured every day (solving the problem of measuring diet complexity and accurately
describing what and how much people eat every day).
The study found that people ate about 500 kilocalories more and gained about a pound per
week when they were eating processed foods. This study design could show causation, not just
correlation, because the other nutritional factors like calories, sugar, fat, fiber, and
macronutrients were held constant, and the diets were tested in the same people, so other
factors such as genetics, sleep, stress, and exercise were constant between the two types of
diets. (This was an example of a crossover randomized controlled trial, in which each subject
serves as their own control, and they completed the processed and unprocessed phases of the
trial in random order.)
Figure 2.6. At left, researchers Kevin Hall and Stephanie Chung talk with one of the processed
foods trial participants at the NIH Clinical Center, an inpatient facility where participants lived
for the duration of the study. At right, an NIH worker prepares meals for participants in the
center’s kitchen. All meals were provided for study participants to carefully control their diet
during the trial.
This study suggested something very important—that food processing causes people to eat
more food and gain weight. However, even the best study design has limitations. For one thing,
this study was small (just 20 participants), and it only lasted for two
1.10.3 49297 weeks, so we don’t know if the findings apply to the general population over
a lifetime of complex, ever-changing diets. The next steps will be to try to repeat the study in
another group of people to see if the finding holds and to design studies to figure out why
processed foods cause increased caloric intake.
As you evaluate nutrition research, especially observational studies, keep in mind the inherent
challenges of nutrition research and look for randomized controlled trials that can help solve
those challenges. Even for randomized controlled trials, consider their limitations, and know that
one study is never enough to fully answer a question in the complex field of nutrition.
Industry Influence: Follow the Money
Understanding how diet influences health is a pressing need. By some estimates, a suboptimal
diet is the single greatest changeable risk factor contributing to death and disability worldwide,
and in the United States, the cost of diet-related chronic diseases are estimated to be as high
as $1 trillion each year.5 Yet, for all its importance, nutrition science has long suffered from a
lack of government investment, with only about 5 percent of the National Institutes of Health
(NIH) budget, or $1.8 billion, directed towards research on how the foods we eat affect our
health, according to a 2019 investigation by Politico. “In 2018, NIH funding for cancer, which
affects just under 9 percent of the population, was $6.3 billion. Funding for obesity, which
affects about 30 percent of the country, was about $1 billion,” the article noted.6
With so little government funding for nutrition science, who is funding the rest of the studies
that feed the constant news cycle? Many are funded by food companies and industry groups,
either to conduct studies in their own research divisions or in the form of grants given to
university scientists. That’s problematic, because food companies and industry groups have an
inherent bias or conflict of interest. Their primary goal is to promote their products and to sell
more of them—not to advance knowledge of food and health—and this affects how they frame
research questions, design and interpret studies, and report their results.
Marion Nestle, a retired nutrition professor at New York University, has written extensively
about this problem. For a year in 2015-2016, she informally tracked industry-funded studies and
found that 90 percent of the time, their conclusions benefited the industry that funded them. In
another example, a 2013 meta-analysis found that among studies that looked at whether soda
consumption contributed to obesity, those funded by the soda industry were five times more
likely to conclude that it doesn’t contribute to obesity compared to those not funded by the
industry.7 (Consider the processed foods RCT we just discussed. It was funded by the National
Institutes of Health, which doesn’t have a stake in the results. Would you trust the results of a
study of processed foods if it was funded by Nabisco? Or for that matter, the Broccoli Growers
of America? Probably not.)
There’s likely a long history of biased nutrition research influencing dietary advice. For example,
in the 1960s, the sugar industry paid well-respected academic scientists to publish research
concluding that it was fat—not sugar—that was detrimental to heart health.8 (Both too much
fat and too much sugar can negatively affect heart health, but it benefited the sugar industry to
focus the blame on fat.) As recently as 2015, Coca-Cola was funding research meant to
promote lack of physical activity as the main cause of obesity, shifting blame away from dietary
factors, such as drinking soda.9 When food companies drive the narrative coming out of
nutrition research, this can potentially impact public policy.
Media attention has made researchers and policy makers much more aware of the problems
with industry funding and conflicts of interest in nutrition research, and they’re working to solve
them. But regardless, if you see reports of a study that shows that blueberries can block
bladder infections, pistachios can prevent pancreatitis, or cinnamon can cure cancer… well, you
should be skeptical, and always check the funding source. Studies on a single type of food are
almost always industry-funded.
It turns out that there has been a randomized controlled trial of processed foods and weight
gain. It was funded by the National Institutes of Health and published in 2019 in the journal Cell
Metabolism.4 In this study, 20 participants lived in the NIH’s Clinical Center for one month,
where they consumed only processed foods for two weeks and only unprocessed foods for
another two weeks, and they could eat as much or as little as they liked during each of these
periods. The diets were carefully designed by dietitians so that they were matched in calories,
sugar, fat, fiber, and macronutrients, and the exact amounts consumed by the participants
were measured every day (solving the problem of measuring diet complexity and accurately
describing what and how much people eat every day).
The study found that people ate about 500 kilocalories more and gained about a pound per
week when they were eating processed foods. This study design could show causation, not just
correlation, because the other nutritional factors like calories, sugar, fat, fiber, and
macronutrients were held constant, and the diets were tested in the same people, so other
factors such as genetics, sleep, stress, and exercise were constant between the two types of
diets. (This was an example of a crossover randomized controlled trial, in which each subject
serves as their own control, and they completed the processed and unprocessed phases of the
trial in random order.)
Figure 2.6. At left, researchers Kevin Hall and Stephanie Chung talk with one of the processed
foods trial participants at the NIH Clinical Center, an inpatient facility where participants lived
for the duration of the study. At right, an NIH worker prepares meals for participants in the
center’s kitchen. All meals were provided for study participants to carefully control their diet
during the trial.
This study suggested something very important—that food processing causes people to eat
more food and gain weight. However, even the best study design has limitations. For one thing,
this study was small (just 20 participants), and it only lasted for two
1.10.3 49297 weeks, so we don’t know if the findings apply to the general population over
a lifetime of complex, ever-changing diets. The next steps will be to try to repeat the study in
another group of people to see if the finding holds and to design studies to figure out why
processed foods cause increased caloric intake.
As you evaluate nutrition research, especially observational studies, keep in mind the inherent
challenges of nutrition research and look for randomized controlled trials that can help solve
those challenges. Even for randomized controlled trials, consider their limitations, and know that
one study is never enough to fully answer a question in the complex field of nutrition.
Industry Influence: Follow the Money
Understanding how diet influences health is a pressing need. By some estimates, a suboptimal
diet is the single greatest changeable risk factor contributing to death and disability worldwide,
and in the United States, the cost of diet-related chronic diseases are estimated to be as high
as $1 trillion each year.5 Yet, for all its importance, nutrition science has long suffered from a
lack of government investment, with only about 5 percent of the National Institutes of Health
(NIH) budget, or $1.8 billion, directed towards research on how the foods we eat affect our
health, according to a 2019 investigation by Politico. “In 2018, NIH funding for cancer, which
affects just under 9 percent of the population, was $6.3 billion. Funding for obesity, which
affects about 30 percent of the country, was about $1 billion,” the article noted.6
With so little government funding for nutrition science, who is funding the rest of the studies
that feed the constant news cycle? Many are funded by food companies and industry groups,
either to conduct studies in their own research divisions or in the form of grants given to
university scientists. That’s problematic, because food companies and industry groups have an
inherent bias or conflict of interest. Their primary goal is to promote their products and to sell
more of them—not to advance knowledge of food and health—and this affects how they frame
research questions, design and interpret studies, and report their results.
Marion Nestle, a retired nutrition professor at New York University, has written extensively
about this problem. For a year in 2015-2016, she informally tracked industry-funded studies and
found that 90 percent of the time, their conclusions benefited the industry that funded them. In
another example, a 2013 meta-analysis found that among studies that looked at whether soda
consumption contributed to obesity, those funded by the soda industry were five times more
likely to conclude that it doesn’t contribute to obesity compared to those not funded by the
industry.7 (Consider the processed foods RCT we just discussed. It was funded by the National
Institutes of Health, which doesn’t have a stake in the results. Would you trust the results of a
study of processed foods if it was funded by Nabisco? Or for that matter, the Broccoli Growers
of America? Probably not.)
There’s likely a long history of biased nutrition research influencing dietary advice. For example,
in the 1960s, the sugar industry paid well-respected academic scientists to publish research
concluding that it was fat—not sugar—that was detrimental to heart health.8 (Both too much
fat and too much sugar can negatively affect heart health, but it benefited the sugar industry to
focus the blame on fat.) As recently as 2015, Coca-Cola was funding research meant to
promote lack of physical activity as the main cause of obesity, shifting blame away from dietary
factors, such as drinking soda.9 When food companies drive the narrative coming out of
nutrition research, this can potentially impact public policy.
Media attention has made researchers and policy makers much more aware of the problems
with industry funding and conflicts of interest in nutrition research, and they’re working to solve
them. But regardless, if you see reports of a study that shows that blueberries can block
bladder infections, pistachios can prevent pancreatitis, or cinnamon can cure cancer… well, you
should be skeptical, and always check the funding source. Studies on a single type of food are
almost always industry-funded.
It turns out that there has been a randomized controlled trial of processed foods and weight
gain. It was funded by the National Institutes of Health and published in 2019 in the journal Cell
Metabolism.4 In this study, 20 participants lived in the NIH’s Clinical Center for one month,
where they consumed only processed foods for two weeks and only unprocessed foods for
another two weeks, and they could eat as much or as little as they liked during each of these
periods. The diets were carefully designed by dietitians so that they were matched in calories,
sugar, fat, fiber, and macronutrients, and the exact amounts consumed by the participants
were measured every day (solving the problem of measuring diet complexity and accurately
describing what and how much people eat every day).
The study found that people ate about 500 kilocalories more and gained about a pound per
week when they were eating processed foods. This study design could show causation, not just
correlation, because the other nutritional factors like calories, sugar, fat, fiber, and
macronutrients were held constant, and the diets were tested in the same people, so other
factors such as genetics, sleep, stress, and exercise were constant between the two types of
diets. (This was an example of a crossover randomized controlled trial, in which each subject
serves as their own control, and they completed the processed and unprocessed phases of the
trial in random order.)
Figure 2.6. At left, researchers Kevin Hall and Stephanie Chung talk with one of the processed
foods trial participants at the NIH Clinical Center, an inpatient facility where participants lived
for the duration of the study. At right, an NIH worker prepares meals for participants in the
center’s kitchen. All meals were provided for study participants to carefully control their diet
during the trial.
This study suggested something very important—that food processing causes people to eat
more food and gain weight. However, even the best study design has limitations. For one thing,
this study was small (just 20 participants), and it only lasted for two
1.10.3 49297 weeks, so we don’t know if the findings apply to the general population over
a lifetime of complex, ever-changing diets. The next steps will be to try to repeat the study in
another group of people to see if the finding holds and to design studies to figure out why
processed foods cause increased caloric intake.
As you evaluate nutrition research, especially observational studies, keep in mind the inherent
challenges of nutrition research and look for randomized controlled trials that can help solve
those challenges. Even for randomized controlled trials, consider their limitations, and know that
one study is never enough to fully answer a question in the complex field of nutrition.
Industry Influence: Follow the Money
Understanding how diet influences health is a pressing need. By some estimates, a suboptimal
diet is the single greatest changeable risk factor contributing to death and disability worldwide,
and in the United States, the cost of diet-related chronic diseases are estimated to be as high
as $1 trillion each year.5 Yet, for all its importance, nutrition science has long suffered from a
lack of government investment, with only about 5 percent of the National Institutes of Health
(NIH) budget, or $1.8 billion, directed towards research on how the foods we eat affect our
health, according to a 2019 investigation by Politico. “In 2018, NIH funding for cancer, which
affects just under 9 percent of the population, was $6.3 billion. Funding for obesity, which
affects about 30 percent of the country, was about $1 billion,” the article noted.6
With so little government funding for nutrition science, who is funding the rest of the studies
that feed the constant news cycle? Many are funded by food companies and industry groups,
either to conduct studies in their own research divisions or in the form of grants given to
university scientists. That’s problematic, because food companies and industry groups have an
inherent bias or conflict of interest. Their primary goal is to promote their products and to sell
more of them—not to advance knowledge of food and health—and this affects how they frame
research questions, design and interpret studies, and report their results.
Marion Nestle, a retired nutrition professor at New York University, has written extensively
about this problem. For a year in 2015-2016, she informally tracked industry-funded studies and
found that 90 percent of the time, their conclusions benefited the industry that funded them. In
another example, a 2013 meta-analysis found that among studies that looked at whether soda
consumption contributed to obesity, those funded by the soda industry were five times more
likely to conclude that it doesn’t contribute to obesity compared to those not funded by the
industry.7 (Consider the processed foods RCT we just discussed. It was funded by the National
Institutes of Health, which doesn’t have a stake in the results. Would you trust the results of a
study of processed foods if it was funded by Nabisco? Or for that matter, the Broccoli Growers
of America? Probably not.)
There’s likely a long history of biased nutrition research influencing dietary advice. For example,
in the 1960s, the sugar industry paid well-respected academic scientists to publish research
concluding that it was fat—not sugar—that was detrimental to heart health.8 (Both too much
fat and too much sugar can negatively affect heart health, but it benefited the sugar industry to
focus the blame on fat.) As recently as 2015, Coca-Cola was funding research meant to
promote lack of physical activity as the main cause of obesity, shifting blame away from dietary
factors, such as drinking soda.9 When food companies drive the narrative coming out of
nutrition research, this can potentially impact public policy.
Media attention has made researchers and policy makers much more aware of the problems
with industry funding and conflicts of interest in nutrition research, and they’re working to solve
them. But regardless, if you see reports of a study that shows that blueberries can block
bladder infections, pistachios can prevent pancreatitis, or cinnamon can cure cancer… well, you
should be skeptical, and always check the funding source. Studies on a single type of food are
almost always industry-funded.
It turns out that there has been a randomized controlled trial of processed foods and weight
gain. It was funded by the National Institutes of Health and published in 2019 in the journal Cell
Metabolism.4 In this study, 20 participants lived in the NIH’s Clinical Center for one month,
where they consumed only processed foods for two weeks and only unprocessed foods for
another two weeks, and they could eat as much or as little as they liked during each of these
periods. The diets were carefully designed by dietitians so that they were matched in calories,
sugar, fat, fiber, and macronutrients, and the exact amounts consumed by the participants
were measured every day (solving the problem of measuring diet complexity and accurately
describing what and how much people eat every day).
The study found that people ate about 500 kilocalories more and gained about a pound per
week when they were eating processed foods. This study design could show causation, not just
correlation, because the other nutritional factors like calories, sugar, fat, fiber, and
macronutrients were held constant, and the diets were tested in the same people, so other
factors such as genetics, sleep, stress, and exercise were constant between the two types of
diets. (This was an example of a crossover randomized controlled trial, in which each subject
serves as their own control, and they completed the processed and unprocessed phases of the
trial in random order.)
Figure 2.6. At left, researchers Kevin Hall and Stephanie Chung talk with one of the processed
foods trial participants at the NIH Clinical Center, an inpatient facility where participants lived
for the duration of the study. At right, an NIH worker prepares meals for participants in the
center’s kitchen. All meals were provided for study participants to carefully control their diet
during the trial.
This study suggested something very important—that food processing causes people to eat
more food and gain weight. However, even the best study design has limitations. For one thing,
this study was small (just 20 participants), and it only lasted for two
1.10.3 49297 weeks, so we don’t know if the findings apply to the general population over
a lifetime of complex, ever-changing diets. The next steps will be to try to repeat the study in
another group of people to see if the finding holds and to design studies to figure out why
processed foods cause increased caloric intake.
As you evaluate nutrition research, especially observational studies, keep in mind the inherent
challenges of nutrition research and look for randomized controlled trials that can help solve
those challenges. Even for randomized controlled trials, consider their limitations, and know that
one study is never enough to fully answer a question in the complex field of nutrition.
Industry Influence: Follow the Money
Understanding how diet influences health is a pressing need. By some estimates, a suboptimal
diet is the single greatest changeable risk factor contributing to death and disability worldwide,
and in the United States, the cost of diet-related chronic diseases are estimated to be as high
as $1 trillion each year.5 Yet, for all its importance, nutrition science has long suffered from a
lack of government investment, with only about 5 percent of the National Institutes of Health
(NIH) budget, or $1.8 billion, directed towards research on how the foods we eat affect our
health, according to a 2019 investigation by Politico. “In 2018, NIH funding for cancer, which
affects just under 9 percent of the population, was $6.3 billion. Funding for obesity, which
affects about 30 percent of the country, was about $1 billion,” the article noted.6
With so little government funding for nutrition science, who is funding the rest of the studies
that feed the constant news cycle? Many are funded by food companies and industry groups,
either to conduct studies in their own research divisions or in the form of grants given to
university scientists. That’s problematic, because food companies and industry groups have an
inherent bias or conflict of interest. Their primary goal is to promote their products and to sell
more of them—not to advance knowledge of food and health—and this affects how they frame
research questions, design and interpret studies, and report their results.
Marion Nestle, a retired nutrition professor at New York University, has written extensively
about this problem. For a year in 2015-2016, she informally tracked industry-funded studies and
found that 90 percent of the time, their conclusions benefited the industry that funded them. In
another example, a 2013 meta-analysis found that among studies that looked at whether soda
consumption contributed to obesity, those funded by the soda industry were five times more
likely to conclude that it doesn’t contribute to obesity compared to those not funded by the
industry.7 (Consider the processed foods RCT we just discussed. It was funded by the National
Institutes of Health, which doesn’t have a stake in the results. Would you trust the results of a
study of processed foods if it was funded by Nabisco? Or for that matter, the Broccoli Growers
of America? Probably not.)
There’s likely a long history of biased nutrition research influencing dietary advice. For example,
in the 1960s, the sugar industry paid well-respected academic scientists to publish research
concluding that it was fat—not sugar—that was detrimental to heart health.8 (Both too much
fat and too much sugar can negatively affect heart health, but it benefited the sugar industry to
focus the blame on fat.) As recently as 2015, Coca-Cola was funding research meant to
promote lack of physical activity as the main cause of obesity, shifting blame away from dietary
factors, such as drinking soda.9 When food companies drive the narrative coming out of
nutrition research, this can potentially impact public policy.
Media attention has made researchers and policy makers much more aware of the problems
with industry funding and conflicts of interest in nutrition research, and they’re working to solve
them. But regardless, if you see reports of a study that shows that blueberries can block
bladder infections, pistachios can prevent pancreatitis, or cinnamon can cure cancer… well, you
should be skeptical, and always check the funding source. Studies on a single type of food are
almost always industry-funded.
It turns out that there has been a randomized controlled trial of processed foods and weight
gain. It was funded by the National Institutes of Health and published in 2019 in the journal Cell
Metabolism.4 In this study, 20 participants lived in the NIH’s Clinical Center for one month,
where they consumed only processed foods for two weeks and only unprocessed foods for
another two weeks, and they could eat as much or as little as they liked during each of these
periods. The diets were carefully designed by dietitians so that they were matched in calories,
sugar, fat, fiber, and macronutrients, and the exact amounts consumed by the participants
were measured every day (solving the problem of measuring diet complexity and accurately
describing what and how much people eat every day).
The study found that people ate about 500 kilocalories more and gained about a pound per
week when they were eating processed foods. This study design could show causation, not just
correlation, because the other nutritional factors like calories, sugar, fat, fiber, and
macronutrients were held constant, and the diets were tested in the same people, so other
factors such as genetics, sleep, stress, and exercise were constant between the two types of
diets. (This was an example of a crossover randomized controlled trial, in which each subject
serves as their own control, and they completed the processed and unprocessed phases of the
trial in random order.)
Figure 2.6. At left, researchers Kevin Hall and Stephanie Chung talk with one of the processed
foods trial participants at the NIH Clinical Center, an inpatient facility where participants lived
for the duration of the study. At right, an NIH worker prepares meals for participants in the
center’s kitchen. All meals were provided for study participants to carefully control their diet
during the trial.
This study suggested something very important—that food processing causes people to eat
more food and gain weight. However, even the best study design has limitations. For one thing,
this study was small (just 20 participants), and it only lasted for two
1.10.3 49297 weeks, so we don’t know if the findings apply to the general population over
a lifetime of complex, ever-changing diets. The next steps will be to try to repeat the study in
another group of people to see if the finding holds and to design studies to figure out why
processed foods cause increased caloric intake.
As you evaluate nutrition research, especially observational studies, keep in mind the inherent
challenges of nutrition research and look for randomized controlled trials that can help solve
those challenges. Even for randomized controlled trials, consider their limitations, and know that
one study is never enough to fully answer a question in the complex field of nutrition.
Industry Influence: Follow the Money
Understanding how diet influences health is a pressing need. By some estimates, a suboptimal
diet is the single greatest changeable risk factor contributing to death and disability worldwide,
and in the United States, the cost of diet-related chronic diseases are estimated to be as high
as $1 trillion each year.5 Yet, for all its importance, nutrition science has long suffered from a
lack of government investment, with only about 5 percent of the National Institutes of Health
(NIH) budget, or $1.8 billion, directed towards research on how the foods we eat affect our
health, according to a 2019 investigation by Politico. “In 2018, NIH funding for cancer, which
affects just under 9 percent of the population, was $6.3 billion. Funding for obesity, which
affects about 30 percent of the country, was about $1 billion,” the article noted.6
With so little government funding for nutrition science, who is funding the rest of the studies
that feed the constant news cycle? Many are funded by food companies and industry groups,
either to conduct studies in their own research divisions or in the form of grants given to
university scientists. That’s problematic, because food companies and industry groups have an
inherent bias or conflict of interest. Their primary goal is to promote their products and to sell
more of them—not to advance knowledge of food and health—and this affects how they frame
research questions, design and interpret studies, and report their results.
Marion Nestle, a retired nutrition professor at New York University, has written extensively
about this problem. For a year in 2015-2016, she informally tracked industry-funded studies and
found that 90 percent of the time, their conclusions benefited the industry that funded them. In
another example, a 2013 meta-analysis found that among studies that looked at whether soda
consumption contributed to obesity, those funded by the soda industry were five times more
likely to conclude that it doesn’t contribute to obesity compared to those not funded by the
industry.7 (Consider the processed foods RCT we just discussed. It was funded by the National
Institutes of Health, which doesn’t have a stake in the results. Would you trust the results of a
study of processed foods if it was funded by Nabisco? Or for that matter, the Broccoli Growers
of America? Probably not.)
There’s likely a long history of biased nutrition research influencing dietary advice. For example,
in the 1960s, the sugar industry paid well-respected academic scientists to publish research
concluding that it was fat—not sugar—that was detrimental to heart health.8 (Both too much
fat and too much sugar can negatively affect heart health, but it benefited the sugar industry to
focus the blame on fat.) As recently as 2015, Coca-Cola was funding research meant to
promote lack of physical activity as the main cause of obesity, shifting blame away from dietary
factors, such as drinking soda.9 When food companies drive the narrative coming out of
nutrition research, this can potentially impact public policy.
Media attention has made researchers and policy makers much more aware of the problems
with industry funding and conflicts of interest in nutrition research, and they’re working to solve
them. But regardless, if you see reports of a study that shows that blueberries can block
bladder infections, pistachios can prevent pancreatitis, or cinnamon can cure cancer… well, you
should be skeptical, and always check the funding source. Studies on a single type of food are
almost always industry-funded.
It turns out that there has been a randomized controlled trial of processed foods and weight
gain. It was funded by the National Institutes of Health and published in 2019 in the journal Cell
Metabolism.4 In this study, 20 participants lived in the NIH’s Clinical Center for one month,
where they consumed only processed foods for two weeks and only unprocessed foods for
another two weeks, and they could eat as much or as little as they liked during each of these
periods. The diets were carefully designed by dietitians so that they were matched in calories,
sugar, fat, fiber, and macronutrients, and the exact amounts consumed by the participants
were measured every day (solving the problem of measuring diet complexity and accurately
describing what and how much people eat every day).
The study found that people ate about 500 kilocalories more and gained about a pound per
week when they were eating processed foods. This study design could show causation, not just
correlation, because the other nutritional factors like calories, sugar, fat, fiber, and
macronutrients were held constant, and the diets were tested in the same people, so other
factors such as genetics, sleep, stress, and exercise were constant between the two types of
diets. (This was an example of a crossover randomized controlled trial, in which each subject
serves as their own control, and they completed the processed and unprocessed phases of the
trial in random order.)
Figure 2.6. At left, researchers Kevin Hall and Stephanie Chung talk with one of the processed
foods trial participants at the NIH Clinical Center, an inpatient facility where participants lived
for the duration of the study. At right, an NIH worker prepares meals for participants in the
center’s kitchen. All meals were provided for study participants to carefully control their diet
during the trial.
This study suggested something very important—that food processing causes people to eat
more food and gain weight. However, even the best study design has limitations. For one thing,
this study was small (just 20 participants), and it only lasted for two
1.10.3 49297 weeks, so we don’t know if the findings apply to the general population over
a lifetime of complex, ever-changing diets. The next steps will be to try to repeat the study in
another group of people to see if the finding holds and to design studies to figure out why
processed foods cause increased caloric intake.
As you evaluate nutrition research, especially observational studies, keep in mind the inherent
challenges of nutrition research and look for randomized controlled trials that can help solve
those challenges. Even for randomized controlled trials, consider their limitations, and know that
one study is never enough to fully answer a question in the complex field of nutrition.
Industry Influence: Follow the Money
Understanding how diet influences health is a pressing need. By some estimates, a suboptimal
diet is the single greatest changeable risk factor contributing to death and disability worldwide,
and in the United States, the cost of diet-related chronic diseases are estimated to be as high
as $1 trillion each year.5 Yet, for all its importance, nutrition science has long suffered from a
lack of government investment, with only about 5 percent of the National Institutes of Health
(NIH) budget, or $1.8 billion, directed towards research on how the foods we eat affect our
health, according to a 2019 investigation by Politico. “In 2018, NIH funding for cancer, which
affects just under 9 percent of the population, was $6.3 billion. Funding for obesity, which
affects about 30 percent of the country, was about $1 billion,” the article noted.6
With so little government funding for nutrition science, who is funding the rest of the studies
that feed the constant news cycle? Many are funded by food companies and industry groups,
either to conduct studies in their own research divisions or in the form of grants given to
university scientists. That’s problematic, because food companies and industry groups have an
inherent bias or conflict of interest. Their primary goal is to promote their products and to sell
more of them—not to advance knowledge of food and health—and this affects how they frame
research questions, design and interpret studies, and report their results.
Marion Nestle, a retired nutrition professor at New York University, has written extensively
about this problem. For a year in 2015-2016, she informally tracked industry-funded studies and
found that 90 percent of the time, their conclusions benefited the industry that funded them. In
another example, a 2013 meta-analysis found that among studies that looked at whether soda
consumption contributed to obesity, those funded by the soda industry were five times more
likely to conclude that it doesn’t contribute to obesity compared to those not funded by the
industry.7 (Consider the processed foods RCT we just discussed. It was funded by the National
Institutes of Health, which doesn’t have a stake in the results. Would you trust the results of a
study of processed foods if it was funded by Nabisco? Or for that matter, the Broccoli Growers
of America? Probably not.)
There’s likely a long history of biased nutrition research influencing dietary advice. For example,
in the 1960s, the sugar industry paid well-respected academic scientists to publish research
concluding that it was fat—not sugar—that was detrimental to heart health.8 (Both too much
fat and too much sugar can negatively affect heart health, but it benefited the sugar industry to
focus the blame on fat.) As recently as 2015, Coca-Cola was funding research meant to
promote lack of physical activity as the main cause of obesity, shifting blame away from dietary
factors, such as drinking soda.9 When food companies drive the narrative coming out of
nutrition research, this can potentially impact public policy.
Media attention has made researchers and policy makers much more aware of the problems
with industry funding and conflicts of interest in nutrition research, and they’re working to solve
them. But regardless, if you see reports of a study that shows that blueberries can block
bladder infections, pistachios can prevent pancreatitis, or cinnamon can cure cancer… well, you
should be skeptical, and always check the funding source. Studies on a single type of food are
almost always industry-funded.
It turns out that there has been a randomized controlled trial of processed foods and weight
gain. It was funded by the National Institutes of Health and published in 2019 in the journal Cell
Metabolism.4 In this study, 20 participants lived in the NIH’s Clinical Center for one month,
where they consumed only processed foods for two weeks and only unprocessed foods for
another two weeks, and they could eat as much or as little as they liked during each of these
periods. The diets were carefully designed by dietitians so that they were matched in calories,
sugar, fat, fiber, and macronutrients, and the exact amounts consumed by the participants
were measured every day (solving the problem of measuring diet complexity and accurately
describing what and how much people eat every day).
The study found that people ate about 500 kilocalories more and gained about a pound per
week when they were eating processed foods. This study design could show causation, not just
correlation, because the other nutritional factors like calories, sugar, fat, fiber, and
macronutrients were held constant, and the diets were tested in the same people, so other
factors such as genetics, sleep, stress, and exercise were constant between the two types of
diets. (This was an example of a crossover randomized controlled trial, in which each subject
serves as their own control, and they completed the processed and unprocessed phases of the
trial in random order.)
Figure 2.6. At left, researchers Kevin Hall and Stephanie Chung talk with one of the processed
foods trial participants at the NIH Clinical Center, an inpatient facility where participants lived
for the duration of the study. At right, an NIH worker prepares meals for participants in the
center’s kitchen. All meals were provided for study participants to carefully control their diet
during the trial.
This study suggested something very important—that food processing causes people to eat
more food and gain weight. However, even the best study design has limitations. For one thing,
this study was small (just 20 participants), and it only lasted for two
1.10.3 49297 weeks, so we don’t know if the findings apply to the general population over
a lifetime of complex, ever-changing diets. The next steps will be to try to repeat the study in
another group of people to see if the finding holds and to design studies to figure out why
processed foods cause increased caloric intake.
As you evaluate nutrition research, especially observational studies, keep in mind the inherent
challenges of nutrition research and look for randomized controlled trials that can help solve
those challenges. Even for randomized controlled trials, consider their limitations, and know that
one study is never enough to fully answer a question in the complex field of nutrition.
Industry Influence: Follow the Money
Understanding how diet influences health is a pressing need. By some estimates, a suboptimal
diet is the single greatest changeable risk factor contributing to death and disability worldwide,
and in the United States, the cost of diet-related chronic diseases are estimated to be as high
as $1 trillion each year.5 Yet, for all its importance, nutrition science has long suffered from a
lack of government investment, with only about 5 percent of the National Institutes of Health
(NIH) budget, or $1.8 billion, directed towards research on how the foods we eat affect our
health, according to a 2019 investigation by Politico. “In 2018, NIH funding for cancer, which
affects just under 9 percent of the population, was $6.3 billion. Funding for obesity, which
affects about 30 percent of the country, was about $1 billion,” the article noted.6
With so little government funding for nutrition science, who is funding the rest of the studies
that feed the constant news cycle? Many are funded by food companies and industry groups,
either to conduct studies in their own research divisions or in the form of grants given to
university scientists. That’s problematic, because food companies and industry groups have an
inherent bias or conflict of interest. Their primary goal is to promote their products and to sell
more of them—not to advance knowledge of food and health—and this affects how they frame
research questions, design and interpret studies, and report their results.
Marion Nestle, a retired nutrition professor at New York University, has written extensively
about this problem. For a year in 2015-2016, she informally tracked industry-funded studies and
found that 90 percent of the time, their conclusions benefited the industry that funded them. In
another example, a 2013 meta-analysis found that among studies that looked at whether soda
consumption contributed to obesity, those funded by the soda industry were five times more
likely to conclude that it doesn’t contribute to obesity compared to those not funded by the
industry.7 (Consider the processed foods RCT we just discussed. It was funded by the National
Institutes of Health, which doesn’t have a stake in the results. Would you trust the results of a
study of processed foods if it was funded by Nabisco? Or for that matter, the Broccoli Growers
of America? Probably not.)
There’s likely a long history of biased nutrition research influencing dietary advice. For example,
in the 1960s, the sugar industry paid well-respected academic scientists to publish research
concluding that it was fat—not sugar—that was detrimental to heart health.8 (Both too much
fat and too much sugar can negatively affect heart health, but it benefited the sugar industry to
focus the blame on fat.) As recently as 2015, Coca-Cola was funding research meant to
promote lack of physical activity as the main cause of obesity, shifting blame away from dietary
factors, such as drinking soda.9 When food companies drive the narrative coming out of
nutrition research, this can potentially impact public policy.
Media attention has made researchers and policy makers much more aware of the problems
with industry funding and conflicts of interest in nutrition research, and they’re working to solve
them. But regardless, if you see reports of a study that shows that blueberries can block
bladder infections, pistachios can prevent pancreatitis, or cinnamon can cure cancer… well, you
should be skeptical, and always check the funding source. Studies on a single type of food are
almost always industry-funded.
It turns out that there has been a randomized controlled trial of processed foods and weight
gain. It was funded by the National Institutes of Health and published in 2019 in the journal Cell
Metabolism.4 In this study, 20 participants lived in the NIH’s Clinical Center for one month,
where they consumed only processed foods for two weeks and only unprocessed foods for
another two weeks, and they could eat as much or as little as they liked during each of these
periods. The diets were carefully designed by dietitians so that they were matched in calories,
sugar, fat, fiber, and macronutrients, and the exact amounts consumed by the participants
were measured every day (solving the problem of measuring diet complexity and accurately
describing what and how much people eat every day).
The study found that people ate about 500 kilocalories more and gained about a pound per
week when they were eating processed foods. This study design could show causation, not just
correlation, because the other nutritional factors like calories, sugar, fat, fiber, and
macronutrients were held constant, and the diets were tested in the same people, so other
factors such as genetics, sleep, stress, and exercise were constant between the two types of
diets. (This was an example of a crossover randomized controlled trial, in which each subject
serves as their own control, and they completed the processed and unprocessed phases of the
trial in random order.)
Figure 2.6. At left, researchers Kevin Hall and Stephanie Chung talk with one of the processed
foods trial participants at the NIH Clinical Center, an inpatient facility where participants lived
for the duration of the study. At right, an NIH worker prepares meals for participants in the
center’s kitchen. All meals were provided for study participants to carefully control their diet
during the trial.
This study suggested something very important—that food processing causes people to eat
more food and gain weight. However, even the best study design has limitations. For one thing,
this study was small (just 20 participants), and it only lasted for two
1.10.3 49297 weeks, so we don’t know if the findings apply to the general population over
a lifetime of complex, ever-changing diets. The next steps will be to try to repeat the study in
another group of people to see if the finding holds and to design studies to figure out why
processed foods cause increased caloric intake.
As you evaluate nutrition research, especially observational studies, keep in mind the inherent
challenges of nutrition research and look for randomized controlled trials that can help solve
those challenges. Even for randomized controlled trials, consider their limitations, and know that
one study is never enough to fully answer a question in the complex field of nutrition.
Industry Influence: Follow the Money
Understanding how diet influences health is a pressing need. By some estimates, a suboptimal
diet is the single greatest changeable risk factor contributing to death and disability worldwide,
and in the United States, the cost of diet-related chronic diseases are estimated to be as high
as $1 trillion each year.5 Yet, for all its importance, nutrition science has long suffered from a
lack of government investment, with only about 5 percent of the National Institutes of Health
(NIH) budget, or $1.8 billion, directed towards research on how the foods we eat affect our
health, according to a 2019 investigation by Politico. “In 2018, NIH funding for cancer, which
affects just under 9 percent of the population, was $6.3 billion. Funding for obesity, which
affects about 30 percent of the country, was about $1 billion,” the article noted.6
With so little government funding for nutrition science, who is funding the rest of the studies
that feed the constant news cycle? Many are funded by food companies and industry groups,
either to conduct studies in their own research divisions or in the form of grants given to
university scientists. That’s problematic, because food companies and industry groups have an
inherent bias or conflict of interest. Their primary goal is to promote their products and to sell
more of them—not to advance knowledge of food and health—and this affects how they frame
research questions, design and interpret studies, and report their results.
Marion Nestle, a retired nutrition professor at New York University, has written extensively
about this problem. For a year in 2015-2016, she informally tracked industry-funded studies and
found that 90 percent of the time, their conclusions benefited the industry that funded them. In
another example, a 2013 meta-analysis found that among studies that looked at whether soda
consumption contributed to obesity, those funded by the soda industry were five times more
likely to conclude that it doesn’t contribute to obesity compared to those not funded by the
industry.7 (Consider the processed foods RCT we just discussed. It was funded by the National
Institutes of Health, which doesn’t have a stake in the results. Would you trust the results of a
study of processed foods if it was funded by Nabisco? Or for that matter, the Broccoli Growers
of America? Probably not.)
There’s likely a long history of biased nutrition research influencing dietary advice. For example,
in the 1960s, the sugar industry paid well-respected academic scientists to publish research
concluding that it was fat—not sugar—that was detrimental to heart health.8 (Both too much
fat and too much sugar can negatively affect heart health, but it benefited the sugar industry to
focus the blame on fat.) As recently as 2015, Coca-Cola was funding research meant to
promote lack of physical activity as the main cause of obesity, shifting blame away from dietary
factors, such as drinking soda.9 When food companies drive the narrative coming out of
nutrition research, this can potentially impact public policy.
Media attention has made researchers and policy makers much more aware of the problems
with industry funding and conflicts of interest in nutrition research, and they’re working to solve
them. But regardless, if you see reports of a study that shows that blueberries can block
bladder infections, pistachios can prevent pancreatitis, or cinnamon can cure cancer… well, you
should be skeptical, and always check the funding source. Studies on a single type of food are
almost always industry-funded.
It turns out that there has been a randomized controlled trial of processed foods and weight
gain. It was funded by the National Institutes of Health and published in 2019 in the journal Cell
Metabolism.4 In this study, 20 participants lived in the NIH’s Clinical Center for one month,
where they consumed only processed foods for two weeks and only unprocessed foods for
another two weeks, and they could eat as much or as little as they liked during each of these
periods. The diets were carefully designed by dietitians so that they were matched in calories,
sugar, fat, fiber, and macronutrients, and the exact amounts consumed by the participants
were measured every day (solving the problem of measuring diet complexity and accurately
describing what and how much people eat every day).
The study found that people ate about 500 kilocalories more and gained about a pound per
week when they were eating processed foods. This study design could show causation, not just
correlation, because the other nutritional factors like calories, sugar, fat, fiber, and
macronutrients were held constant, and the diets were tested in the same people, so other
factors such as genetics, sleep, stress, and exercise were constant between the two types of
diets. (This was an example of a crossover randomized controlled trial, in which each subject
serves as their own control, and they completed the processed and unprocessed phases of the
trial in random order.)
Figure 2.6. At left, researchers Kevin Hall and Stephanie Chung talk with one of the processed
foods trial participants at the NIH Clinical Center, an inpatient facility where participants lived
for the duration of the study. At right, an NIH worker prepares meals for participants in the
center’s kitchen. All meals were provided for study participants to carefully control their diet
during the trial.
This study suggested something very important—that food processing causes people to eat
more food and gain weight. However, even the best study design has limitations. For one thing,
this study was small (just 20 participants), and it only lasted for two
1.10.3 49297 weeks, so we don’t know if the findings apply to the general population over
a lifetime of complex, ever-changing diets. The next steps will be to try to repeat the study in
another group of people to see if the finding holds and to design studies to figure out why
processed foods cause increased caloric intake.
As you evaluate nutrition research, especially observational studies, keep in mind the inherent
challenges of nutrition research and look for randomized controlled trials that can help solve
those challenges. Even for randomized controlled trials, consider their limitations, and know that
one study is never enough to fully answer a question in the complex field of nutrition.
Industry Influence: Follow the Money
Understanding how diet influences health is a pressing need. By some estimates, a suboptimal
diet is the single greatest changeable risk factor contributing to death and disability worldwide,
and in the United States, the cost of diet-related chronic diseases are estimated to be as high
as $1 trillion each year.5 Yet, for all its importance, nutrition science has long suffered from a
lack of government investment, with only about 5 percent of the National Institutes of Health
(NIH) budget, or $1.8 billion, directed towards research on how the foods we eat affect our
health, according to a 2019 investigation by Politico. “In 2018, NIH funding for cancer, which
affects just under 9 percent of the population, was $6.3 billion. Funding for obesity, which
affects about 30 percent of the country, was about $1 billion,” the article noted.6
With so little government funding for nutrition science, who is funding the rest of the studies
that feed the constant news cycle? Many are funded by food companies and industry groups,
either to conduct studies in their own research divisions or in the form of grants given to
university scientists. That’s problematic, because food companies and industry groups have an
inherent bias or conflict of interest. Their primary goal is to promote their products and to sell
more of them—not to advance knowledge of food and health—and this affects how they frame
research questions, design and interpret studies, and report their results.
Marion Nestle, a retired nutrition professor at New York University, has written extensively
about this problem. For a year in 2015-2016, she informally tracked industry-funded studies and
found that 90 percent of the time, their conclusions benefited the industry that funded them. In
another example, a 2013 meta-analysis found that among studies that looked at whether soda
consumption contributed to obesity, those funded by the soda industry were five times more
likely to conclude that it doesn’t contribute to obesity compared to those not funded by the
industry.7 (Consider the processed foods RCT we just discussed. It was funded by the National
Institutes of Health, which doesn’t have a stake in the results. Would you trust the results of a
study of processed foods if it was funded by Nabisco? Or for that matter, the Broccoli Growers
of America? Probably not.)
There’s likely a long history of biased nutrition research influencing dietary advice. For example,
in the 1960s, the sugar industry paid well-respected academic scientists to publish research
concluding that it was fat—not sugar—that was detrimental to heart health.8 (Both too much
fat and too much sugar can negatively affect heart health, but it benefited the sugar industry to
focus the blame on fat.) As recently as 2015, Coca-Cola was funding research meant to
promote lack of physical activity as the main cause of obesity, shifting blame away from dietary
factors, such as drinking soda.9 When food companies drive the narrative coming out of
nutrition research, this can potentially impact public policy.
Media attention has made researchers and policy makers much more aware of the problems
with industry funding and conflicts of interest in nutrition research, and they’re working to solve
them. But regardless, if you see reports of a study that shows that blueberries can block
bladder infections, pistachios can prevent pancreatitis, or cinnamon can cure cancer… well, you
should be skeptical, and always check the funding source. Studies on a single type of food are
almost always industry-funded.
It turns out that there has been a randomized controlled trial of processed foods and weight
gain. It was funded by the National Institutes of Health and published in 2019 in the journal Cell
Metabolism.4 In this study, 20 participants lived in the NIH’s Clinical Center for one month,
where they consumed only processed foods for two weeks and only unprocessed foods for
another two weeks, and they could eat as much or as little as they liked during each of these
periods. The diets were carefully designed by dietitians so that they were matched in calories,
sugar, fat, fiber, and macronutrients, and the exact amounts consumed by the participants
were measured every day (solving the problem of measuring diet complexity and accurately
describing what and how much people eat every day).
The study found that people ate about 500 kilocalories more and gained about a pound per
week when they were eating processed foods. This study design could show causation, not just
correlation, because the other nutritional factors like calories, sugar, fat, fiber, and
macronutrients were held constant, and the diets were tested in the same people, so other
factors such as genetics, sleep, stress, and exercise were constant between the two types of
diets. (This was an example of a crossover randomized controlled trial, in which each subject
serves as their own control, and they completed the processed and unprocessed phases of the
trial in random order.)
Figure 2.6. At left, researchers Kevin Hall and Stephanie Chung talk with one of the processed
foods trial participants at the NIH Clinical Center, an inpatient facility where participants lived
for the duration of the study. At right, an NIH worker prepares meals for participants in the
center’s kitchen. All meals were provided for study participants to carefully control their diet
during the trial.
This study suggested something very important—that food processing causes people to eat
more food and gain weight. However, even the best study design has limitations. For one thing,
this study was small (just 20 participants), and it only lasted for two
1.10.3 49297 weeks, so we don’t know if the findings apply to the general population over
a lifetime of complex, ever-changing diets. The next steps will be to try to repeat the study in
another group of people to see if the finding holds and to design studies to figure out why
processed foods cause increased caloric intake.
As you evaluate nutrition research, especially observational studies, keep in mind the inherent
challenges of nutrition research and look for randomized controlled trials that can help solve
those challenges. Even for randomized controlled trials, consider their limitations, and know that
one study is never enough to fully answer a question in the complex field of nutrition.
Industry Influence: Follow the Money
Understanding how diet influences health is a pressing need. By some estimates, a suboptimal
diet is the single greatest changeable risk factor contributing to death and disability worldwide,
and in the United States, the cost of diet-related chronic diseases are estimated to be as high
as $1 trillion each year.5 Yet, for all its importance, nutrition science has long suffered from a
lack of government investment, with only about 5 percent of the National Institutes of Health
(NIH) budget, or $1.8 billion, directed towards research on how the foods we eat affect our
health, according to a 2019 investigation by Politico. “In 2018, NIH funding for cancer, which
affects just under 9 percent of the population, was $6.3 billion. Funding for obesity, which
affects about 30 percent of the country, was about $1 billion,” the article noted.6
With so little government funding for nutrition science, who is funding the rest of the studies
that feed the constant news cycle? Many are funded by food companies and industry groups,
either to conduct studies in their own research divisions or in the form of grants given to
university scientists. That’s problematic, because food companies and industry groups have an
inherent bias or conflict of interest. Their primary goal is to promote their products and to sell
more of them—not to advance knowledge of food and health—and this affects how they frame
research questions, design and interpret studies, and report their results.
Marion Nestle, a retired nutrition professor at New York University, has written extensively
about this problem. For a year in 2015-2016, she informally tracked industry-funded studies and
found that 90 percent of the time, their conclusions benefited the industry that funded them. In
another example, a 2013 meta-analysis found that among studies that looked at whether soda
consumption contributed to obesity, those funded by the soda industry were five times more
likely to conclude that it doesn’t contribute to obesity compared to those not funded by the
industry.7 (Consider the processed foods RCT we just discussed. It was funded by the National
Institutes of Health, which doesn’t have a stake in the results. Would you trust the results of a
study of processed foods if it was funded by Nabisco? Or for that matter, the Broccoli Growers
of America? Probably not.)
There’s likely a long history of biased nutrition research influencing dietary advice. For example,
in the 1960s, the sugar industry paid well-respected academic scientists to publish research
concluding that it was fat—not sugar—that was detrimental to heart health.8 (Both too much
fat and too much sugar can negatively affect heart health, but it benefited the sugar industry to
focus the blame on fat.) As recently as 2015, Coca-Cola was funding research meant to
promote lack of physical activity as the main cause of obesity, shifting blame away from dietary
factors, such as drinking soda.9 When food companies drive the narrative coming out of
nutrition research, this can potentially impact public policy.
Media attention has made researchers and policy makers much more aware of the problems
with industry funding and conflicts of interest in nutrition research, and they’re working to solve
them. But regardless, if you see reports of a study that shows that blueberries can block
bladder infections, pistachios can prevent pancreatitis, or cinnamon can cure cancer… well, you
should be skeptical, and always check the funding source. Studies on a single type of food are
almost always industry-funded.
It turns out that there has been a randomized controlled trial of processed foods and weight
gain. It was funded by the National Institutes of Health and published in 2019 in the journal Cell
Metabolism.4 In this study, 20 participants lived in the NIH’s Clinical Center for one month,
where they consumed only processed foods for two weeks and only unprocessed foods for
another two weeks, and they could eat as much or as little as they liked during each of these
periods. The diets were carefully designed by dietitians so that they were matched in calories,
sugar, fat, fiber, and macronutrients, and the exact amounts consumed by the participants
were measured every day (solving the problem of measuring diet complexity and accurately
describing what and how much people eat every day).
The study found that people ate about 500 kilocalories more and gained about a pound per
week when they were eating processed foods. This study design could show causation, not just
correlation, because the other nutritional factors like calories, sugar, fat, fiber, and
macronutrients were held constant, and the diets were tested in the same people, so other
factors such as genetics, sleep, stress, and exercise were constant between the two types of
diets. (This was an example of a crossover randomized controlled trial, in which each subject
serves as their own control, and they completed the processed and unprocessed phases of the
trial in random order.)
Figure 2.6. At left, researchers Kevin Hall and Stephanie Chung talk with one of the processed
foods trial participants at the NIH Clinical Center, an inpatient facility where participants lived
for the duration of the study. At right, an NIH worker prepares meals for participants in the
center’s kitchen. All meals were provided for study participants to carefully control their diet
during the trial.
This study suggested something very important—that food processing causes people to eat
more food and gain weight. However, even the best study design has limitations. For one thing,
this study was small (just 20 participants), and it only lasted for two
1.10.3 49297 weeks, so we don’t know if the findings apply to the general population over
a lifetime of complex, ever-changing diets. The next steps will be to try to repeat the study in
another group of people to see if the finding holds and to design studies to figure out why
processed foods cause increased caloric intake.
As you evaluate nutrition research, especially observational studies, keep in mind the inherent
challenges of nutrition research and look for randomized controlled trials that can help solve
those challenges. Even for randomized controlled trials, consider their limitations, and know that
one study is never enough to fully answer a question in the complex field of nutrition.
Industry Influence: Follow the Money
Understanding how diet influences health is a pressing need. By some estimates, a suboptimal
diet is the single greatest changeable risk factor contributing to death and disability worldwide,
and in the United States, the cost of diet-related chronic diseases are estimated to be as high
as $1 trillion each year.5 Yet, for all its importance, nutrition science has long suffered from a
lack of government investment, with only about 5 percent of the National Institutes of Health
(NIH) budget, or $1.8 billion, directed towards research on how the foods we eat affect our
health, according to a 2019 investigation by Politico. “In 2018, NIH funding for cancer, which
affects just under 9 percent of the population, was $6.3 billion. Funding for obesity, which
affects about 30 percent of the country, was about $1 billion,” the article noted.6
With so little government funding for nutrition science, who is funding the rest of the studies
that feed the constant news cycle? Many are funded by food companies and industry groups,
either to conduct studies in their own research divisions or in the form of grants given to
university scientists. That’s problematic, because food companies and industry groups have an
inherent bias or conflict of interest. Their primary goal is to promote their products and to sell
more of them—not to advance knowledge of food and health—and this affects how they frame
research questions, design and interpret studies, and report their results.
Marion Nestle, a retired nutrition professor at New York University, has written extensively
about this problem. For a year in 2015-2016, she informally tracked industry-funded studies and
found that 90 percent of the time, their conclusions benefited the industry that funded them. In
another example, a 2013 meta-analysis found that among studies that looked at whether soda
consumption contributed to obesity, those funded by the soda industry were five times more
likely to conclude that it doesn’t contribute to obesity compared to those not funded by the
industry.7 (Consider the processed foods RCT we just discussed. It was funded by the National
Institutes of Health, which doesn’t have a stake in the results. Would you trust the results of a
study of processed foods if it was funded by Nabisco? Or for that matter, the Broccoli Growers
of America? Probably not.)
There’s likely a long history of biased nutrition research influencing dietary advice. For example,
in the 1960s, the sugar industry paid well-respected academic scientists to publish research
concluding that it was fat—not sugar—that was detrimental to heart health.8 (Both too much
fat and too much sugar can negatively affect heart health, but it benefited the sugar industry to
focus the blame on fat.) As recently as 2015, Coca-Cola was funding research meant to
promote lack of physical activity as the main cause of obesity, shifting blame away from dietary
factors, such as drinking soda.9 When food companies drive the narrative coming out of
nutrition research, this can potentially impact public policy.
Media attention has made researchers and policy makers much more aware of the problems
with industry funding and conflicts of interest in nutrition research, and they’re working to solve
them. But regardless, if you see reports of a study that shows that blueberries can block
bladder infections, pistachios can prevent pancreatitis, or cinnamon can cure cancer… well, you
should be skeptical, and always check the funding source. Studies on a single type of food are
almost always industry-funded.
It turns out that there has been a randomized controlled trial of processed foods and weight
gain. It was funded by the National Institutes of Health and published in 2019 in the journal Cell
Metabolism.4 In this study, 20 participants lived in the NIH’s Clinical Center for one month,
where they consumed only processed foods for two weeks and only unprocessed foods for
another two weeks, and they could eat as much or as little as they liked during each of these
periods. The diets were carefully designed by dietitians so that they were matched in calories,
sugar, fat, fiber, and macronutrients, and the exact amounts consumed by the participants
were measured every day (solving the problem of measuring diet complexity and accurately
describing what and how much people eat every day).
The study found that people ate about 500 kilocalories more and gained about a pound per
week when they were eating processed foods. This study design could show causation, not just
correlation, because the other nutritional factors like calories, sugar, fat, fiber, and
macronutrients were held constant, and the diets were tested in the same people, so other
factors such as genetics, sleep, stress, and exercise were constant between the two types of
diets. (This was an example of a crossover randomized controlled trial, in which each subject
serves as their own control, and they completed the processed and unprocessed phases of the
trial in random order.)
Figure 2.6. At left, researchers Kevin Hall and Stephanie Chung talk with one of the processed
foods trial participants at the NIH Clinical Center, an inpatient facility where participants lived
for the duration of the study. At right, an NIH worker prepares meals for participants in the
center’s kitchen. All meals were provided for study participants to carefully control their diet
during the trial.
This study suggested something very important—that food processing causes people to eat
more food and gain weight. However, even the best study design has limitations. For one thing,
this study was small (just 20 participants), and it only lasted for two
1.10.3 49297 weeks, so we don’t know if the findings apply to the general population over
a lifetime of complex, ever-changing diets. The next steps will be to try to repeat the study in
another group of people to see if the finding holds and to design studies to figure out why
processed foods cause increased caloric intake.
As you evaluate nutrition research, especially observational studies, keep in mind the inherent
challenges of nutrition research and look for randomized controlled trials that can help solve
those challenges. Even for randomized controlled trials, consider their limitations, and know that
one study is never enough to fully answer a question in the complex field of nutrition.
Industry Influence: Follow the Money
Understanding how diet influences health is a pressing need. By some estimates, a suboptimal
diet is the single greatest changeable risk factor contributing to death and disability worldwide,
and in the United States, the cost of diet-related chronic diseases are estimated to be as high
as $1 trillion each year.5 Yet, for all its importance, nutrition science has long suffered from a
lack of government investment, with only about 5 percent of the National Institutes of Health
(NIH) budget, or $1.8 billion, directed towards research on how the foods we eat affect our
health, according to a 2019 investigation by Politico. “In 2018, NIH funding for cancer, which
affects just under 9 percent of the population, was $6.3 billion. Funding for obesity, which
affects about 30 percent of the country, was about $1 billion,” the article noted.6
With so little government funding for nutrition science, who is funding the rest of the studies
that feed the constant news cycle? Many are funded by food companies and industry groups,
either to conduct studies in their own research divisions or in the form of grants given to
university scientists. That’s problematic, because food companies and industry groups have an
inherent bias or conflict of interest. Their primary goal is to promote their products and to sell
more of them—not to advance knowledge of food and health—and this affects how they frame
research questions, design and interpret studies, and report their results.
Marion Nestle, a retired nutrition professor at New York University, has written extensively
about this problem. For a year in 2015-2016, she informally tracked industry-funded studies and
found that 90 percent of the time, their conclusions benefited the industry that funded them. In
another example, a 2013 meta-analysis found that among studies that looked at whether soda
consumption contributed to obesity, those funded by the soda industry were five times more
likely to conclude that it doesn’t contribute to obesity compared to those not funded by the
industry.7 (Consider the processed foods RCT we just discussed. It was funded by the National
Institutes of Health, which doesn’t have a stake in the results. Would you trust the results of a
study of processed foods if it was funded by Nabisco? Or for that matter, the Broccoli Growers
of America? Probably not.)
There’s likely a long history of biased nutrition research influencing dietary advice. For example,
in the 1960s, the sugar industry paid well-respected academic scientists to publish research
concluding that it was fat—not sugar—that was detrimental to heart health.8 (Both too much
fat and too much sugar can negatively affect heart health, but it benefited the sugar industry to
focus the blame on fat.) As recently as 2015, Coca-Cola was funding research meant to
promote lack of physical activity as the main cause of obesity, shifting blame away from dietary
factors, such as drinking soda.9 When food companies drive the narrative coming out of
nutrition research, this can potentially impact public policy.
Media attention has made researchers and policy makers much more aware of the problems
with industry funding and conflicts of interest in nutrition research, and they’re working to solve
them. But regardless, if you see reports of a study that shows that blueberries can block
bladder infections, pistachios can prevent pancreatitis, or cinnamon can cure cancer… well, you
should be skeptical, and always check the funding source. Studies on a single type of food are
almost always industry-funded.
It turns out that there has been a randomized controlled trial of processed foods and weight
gain. It was funded by the National Institutes of Health and published in 2019 in the journal Cell
Metabolism.4 In this study, 20 participants lived in the NIH’s Clinical Center for one month,
where they consumed only processed foods for two weeks and only unprocessed foods for
another two weeks, and they could eat as much or as little as they liked during each of these
periods. The diets were carefully designed by dietitians so that they were matched in calories,
sugar, fat, fiber, and macronutrients, and the exact amounts consumed by the participants
were measured every day (solving the problem of measuring diet complexity and accurately
describing what and how much people eat every day).
The study found that people ate about 500 kilocalories more and gained about a pound per
week when they were eating processed foods. This study design could show causation, not just
correlation, because the other nutritional factors like calories, sugar, fat, fiber, and
macronutrients were held constant, and the diets were tested in the same people, so other
factors such as genetics, sleep, stress, and exercise were constant between the two types of
diets. (This was an example of a crossover randomized controlled trial, in which each subject
serves as their own control, and they completed the processed and unprocessed phases of the
trial in random order.)
Figure 2.6. At left, researchers Kevin Hall and Stephanie Chung talk with one of the processed
foods trial participants at the NIH Clinical Center, an inpatient facility where participants lived
for the duration of the study. At right, an NIH worker prepares meals for participants in the
center’s kitchen. All meals were provided for study participants to carefully control their diet
during the trial.
This study suggested something very important—that food processing causes people to eat
more food and gain weight. However, even the best study design has limitations. For one thing,
this study was small (just 20 participants), and it only lasted for two
1.10.3 49297 weeks, so we don’t know if the findings apply to the general population over
a lifetime of complex, ever-changing diets. The next steps will be to try to repeat the study in
another group of people to see if the finding holds and to design studies to figure out why
processed foods cause increased caloric intake.
As you evaluate nutrition research, especially observational studies, keep in mind the inherent
challenges of nutrition research and look for randomized controlled trials that can help solve
those challenges. Even for randomized controlled trials, consider their limitations, and know that
one study is never enough to fully answer a question in the complex field of nutrition.
Industry Influence: Follow the Money
Understanding how diet influences health is a pressing need. By some estimates, a suboptimal
diet is the single greatest changeable risk factor contributing to death and disability worldwide,
and in the United States, the cost of diet-related chronic diseases are estimated to be as high
as $1 trillion each year.5 Yet, for all its importance, nutrition science has long suffered from a
lack of government investment, with only about 5 percent of the National Institutes of Health
(NIH) budget, or $1.8 billion, directed towards research on how the foods we eat affect our
health, according to a 2019 investigation by Politico. “In 2018, NIH funding for cancer, which
affects just under 9 percent of the population, was $6.3 billion. Funding for obesity, which
affects about 30 percent of the country, was about $1 billion,” the article noted.6
With so little government funding for nutrition science, who is funding the rest of the studies
that feed the constant news cycle? Many are funded by food companies and industry groups,
either to conduct studies in their own research divisions or in the form of grants given to
university scientists. That’s problematic, because food companies and industry groups have an
inherent bias or conflict of interest. Their primary goal is to promote their products and to sell
more of them—not to advance knowledge of food and health—and this affects how they frame
research questions, design and interpret studies, and report their results.
Marion Nestle, a retired nutrition professor at New York University, has written extensively
about this problem. For a year in 2015-2016, she informally tracked industry-funded studies and
found that 90 percent of the time, their conclusions benefited the industry that funded them. In
another example, a 2013 meta-analysis found that among studies that looked at whether soda
consumption contributed to obesity, those funded by the soda industry were five times more
likely to conclude that it doesn’t contribute to obesity compared to those not funded by the
industry.7 (Consider the processed foods RCT we just discussed. It was funded by the National
Institutes of Health, which doesn’t have a stake in the results. Would you trust the results of a
study of processed foods if it was funded by Nabisco? Or for that matter, the Broccoli Growers
of America? Probably not.)
There’s likely a long history of biased nutrition research influencing dietary advice. For example,
in the 1960s, the sugar industry paid well-respected academic scientists to publish research
concluding that it was fat—not sugar—that was detrimental to heart health.8 (Both too much
fat and too much sugar can negatively affect heart health, but it benefited the sugar industry to
focus the blame on fat.) As recently as 2015, Coca-Cola was funding research meant to
promote lack of physical activity as the main cause of obesity, shifting blame away from dietary
factors, such as drinking soda.9 When food companies drive the narrative coming out of
nutrition research, this can potentially impact public policy.
Media attention has made researchers and policy makers much more aware of the problems
with industry funding and conflicts of interest in nutrition research, and they’re working to solve
them. But regardless, if you see reports of a study that shows that blueberries can block
bladder infections, pistachios can prevent pancreatitis, or cinnamon can cure cancer… well, you
should be skeptical, and always check the funding source. Studies on a single type of food are
almost always industry-funded.
It turns out that there has been a randomized controlled trial of processed foods and weight
gain. It was funded by the National Institutes of Health and published in 2019 in the journal Cell
Metabolism.4 In this study, 20 participants lived in the NIH’s Clinical Center for one month,
where they consumed only processed foods for two weeks and only unprocessed foods for
another two weeks, and they could eat as much or as little as they liked during each of these
periods. The diets were carefully designed by dietitians so that they were matched in calories,
sugar, fat, fiber, and macronutrients, and the exact amounts consumed by the participants
were measured every day (solving the problem of measuring diet complexity and accurately
describing what and how much people eat every day).
The study found that people ate about 500 kilocalories more and gained about a pound per
week when they were eating processed foods. This study design could show causation, not just
correlation, because the other nutritional factors like calories, sugar, fat, fiber, and
macronutrients were held constant, and the diets were tested in the same people, so other
factors such as genetics, sleep, stress, and exercise were constant between the two types of
diets. (This was an example of a crossover randomized controlled trial, in which each subject
serves as their own control, and they completed the processed and unprocessed phases of the
trial in random order.)
Figure 2.6. At left, researchers Kevin Hall and Stephanie Chung talk with one of the processed
foods trial participants at the NIH Clinical Center, an inpatient facility where participants lived
for the duration of the study. At right, an NIH worker prepares meals for participants in the
center’s kitchen. All meals were provided for study participants to carefully control their diet
during the trial.
This study suggested something very important—that food processing causes people to eat
more food and gain weight. However, even the best study design has limitations. For one thing,
this study was small (just 20 participants), and it only lasted for two
1.10.3 49297 weeks, so we don’t know if the findings apply to the general population over
a lifetime of complex, ever-changing diets. The next steps will be to try to repeat the study in
another group of people to see if the finding holds and to design studies to figure out why
processed foods cause increased caloric intake.
As you evaluate nutrition research, especially observational studies, keep in mind the inherent
challenges of nutrition research and look for randomized controlled trials that can help solve
those challenges. Even for randomized controlled trials, consider their limitations, and know that
one study is never enough to fully answer a question in the complex field of nutrition.
Industry Influence: Follow the Money
Understanding how diet influences health is a pressing need. By some estimates, a suboptimal
diet is the single greatest changeable risk factor contributing to death and disability worldwide,
and in the United States, the cost of diet-related chronic diseases are estimated to be as high
as $1 trillion each year.5 Yet, for all its importance, nutrition science has long suffered from a
lack of government investment, with only about 5 percent of the National Institutes of Health
(NIH) budget, or $1.8 billion, directed towards research on how the foods we eat affect our
health, according to a 2019 investigation by Politico. “In 2018, NIH funding for cancer, which
affects just under 9 percent of the population, was $6.3 billion. Funding for obesity, which
affects about 30 percent of the country, was about $1 billion,” the article noted.6
With so little government funding for nutrition science, who is funding the rest of the studies
that feed the constant news cycle? Many are funded by food companies and industry groups,
either to conduct studies in their own research divisions or in the form of grants given to
university scientists. That’s problematic, because food companies and industry groups have an
inherent bias or conflict of interest. Their primary goal is to promote their products and to sell
more of them—not to advance knowledge of food and health—and this affects how they frame
research questions, design and interpret studies, and report their results.
Marion Nestle, a retired nutrition professor at New York University, has written extensively
about this problem. For a year in 2015-2016, she informally tracked industry-funded studies and
found that 90 percent of the time, their conclusions benefited the industry that funded them. In
another example, a 2013 meta-analysis found that among studies that looked at whether soda
consumption contributed to obesity, those funded by the soda industry were five times more
likely to conclude that it doesn’t contribute to obesity compared to those not funded by the
industry.7 (Consider the processed foods RCT we just discussed. It was funded by the National
Institutes of Health, which doesn’t have a stake in the results. Would you trust the results of a
study of processed foods if it was funded by Nabisco? Or for that matter, the Broccoli Growers
of America? Probably not.)
There’s likely a long history of biased nutrition research influencing dietary advice. For example,
in the 1960s, the sugar industry paid well-respected academic scientists to publish research
concluding that it was fat—not sugar—that was detrimental to heart health.8 (Both too much
fat and too much sugar can negatively affect heart health, but it benefited the sugar industry to
focus the blame on fat.) As recently as 2015, Coca-Cola was funding research meant to
promote lack of physical activity as the main cause of obesity, shifting blame away from dietary
factors, such as drinking soda.9 When food companies drive the narrative coming out of
nutrition research, this can potentially impact public policy.
Media attention has made researchers and policy makers much more aware of the problems
with industry funding and conflicts of interest in nutrition research, and they’re working to solve
them. But regardless, if you see reports of a study that shows that blueberries can block
bladder infections, pistachios can prevent pancreatitis, or cinnamon can cure cancer… well, you
should be skeptical, and always check the funding source. Studies on a single type of food are
almost always industry-funded.
It turns out that there has been a randomized controlled trial of processed foods and weight
gain. It was funded by the National Institutes of Health and published in 2019 in the journal Cell
Metabolism.4 In this study, 20 participants lived in the NIH’s Clinical Center for one month,
where they consumed only processed foods for two weeks and only unprocessed foods for
another two weeks, and they could eat as much or as little as they liked during each of these
periods. The diets were carefully designed by dietitians so that they were matched in calories,
sugar, fat, fiber, and macronutrients, and the exact amounts consumed by the participants
were measured every day (solving the problem of measuring diet complexity and accurately
describing what and how much people eat every day).
The study found that people ate about 500 kilocalories more and gained about a pound per
week when they were eating processed foods. This study design could show causation, not just
correlation, because the other nutritional factors like calories, sugar, fat, fiber, and
macronutrients were held constant, and the diets were tested in the same people, so other
factors such as genetics, sleep, stress, and exercise were constant between the two types of
diets. (This was an example of a crossover randomized controlled trial, in which each subject
serves as their own control, and they completed the processed and unprocessed phases of the
trial in random order.)
Figure 2.6. At left, researchers Kevin Hall and Stephanie Chung talk with one of the processed
foods trial participants at the NIH Clinical Center, an inpatient facility where participants lived
for the duration of the study. At right, an NIH worker prepares meals for participants in the
center’s kitchen. All meals were provided for study participants to carefully control their diet
during the trial.
This study suggested something very important—that food processing causes people to eat
more food and gain weight. However, even the best study design has limitations. For one thing,
this study was small (just 20 participants), and it only lasted for two
1.10.3 49297 weeks, so we don’t know if the findings apply to the general population over
a lifetime of complex, ever-changing diets. The next steps will be to try to repeat the study in
another group of people to see if the finding holds and to design studies to figure out why
processed foods cause increased caloric intake.
As you evaluate nutrition research, especially observational studies, keep in mind the inherent
challenges of nutrition research and look for randomized controlled trials that can help solve
those challenges. Even for randomized controlled trials, consider their limitations, and know that
one study is never enough to fully answer a question in the complex field of nutrition.
Industry Influence: Follow the Money
Understanding how diet influences health is a pressing need. By some estimates, a suboptimal
diet is the single greatest changeable risk factor contributing to death and disability worldwide,
and in the United States, the cost of diet-related chronic diseases are estimated to be as high
as $1 trillion each year.5 Yet, for all its importance, nutrition science has long suffered from a
lack of government investment, with only about 5 percent of the National Institutes of Health
(NIH) budget, or $1.8 billion, directed towards research on how the foods we eat affect our
health, according to a 2019 investigation by Politico. “In 2018, NIH funding for cancer, which
affects just under 9 percent of the population, was $6.3 billion. Funding for obesity, which
affects about 30 percent of the country, was about $1 billion,” the article noted.6
With so little government funding for nutrition science, who is funding the rest of the studies
that feed the constant news cycle? Many are funded by food companies and industry groups,
either to conduct studies in their own research divisions or in the form of grants given to
university scientists. That’s problematic, because food companies and industry groups have an
inherent bias or conflict of interest. Their primary goal is to promote their products and to sell
more of them—not to advance knowledge of food and health—and this affects how they frame
research questions, design and interpret studies, and report their results.
Marion Nestle, a retired nutrition professor at New York University, has written extensively
about this problem. For a year in 2015-2016, she informally tracked industry-funded studies and
found that 90 percent of the time, their conclusions benefited the industry that funded them. In
another example, a 2013 meta-analysis found that among studies that looked at whether soda
consumption contributed to obesity, those funded by the soda industry were five times more
likely to conclude that it doesn’t contribute to obesity compared to those not funded by the
industry.7 (Consider the processed foods RCT we just discussed. It was funded by the National
Institutes of Health, which doesn’t have a stake in the results. Would you trust the results of a
study of processed foods if it was funded by Nabisco? Or for that matter, the Broccoli Growers
of America? Probably not.)
There’s likely a long history of biased nutrition research influencing dietary advice. For example,
in the 1960s, the sugar industry paid well-respected academic scientists to publish research
concluding that it was fat—not sugar—that was detrimental to heart health.8 (Both too much
fat and too much sugar can negatively affect heart health, but it benefited the sugar industry to
focus the blame on fat.) As recently as 2015, Coca-Cola was funding research meant to
promote lack of physical activity as the main cause of obesity, shifting blame away from dietary
factors, such as drinking soda.9 When food companies drive the narrative coming out of
nutrition research, this can potentially impact public policy.
Media attention has made researchers and policy makers much more aware of the problems
with industry funding and conflicts of interest in nutrition research, and they’re working to solve
them. But regardless, if you see reports of a study that shows that blueberries can block
bladder infections, pistachios can prevent pancreatitis, or cinnamon can cure cancer… well, you
should be skeptical, and always check the funding source. Studies on a single type of food are
almost always industry-funded.
It turns out that there has been a randomized controlled trial of processed foods and weight
gain. It was funded by the National Institutes of Health and published in 2019 in the journal Cell
Metabolism.4 In this study, 20 participants lived in the NIH’s Clinical Center for one month,
where they consumed only processed foods for two weeks and only unprocessed foods for
another two weeks, and they could eat as much or as little as they liked during each of these
periods. The diets were carefully designed by dietitians so that they were matched in calories,
sugar, fat, fiber, and macronutrients, and the exact amounts consumed by the participants
were measured every day (solving the problem of measuring diet complexity and accurately
describing what and how much people eat every day).
The study found that people ate about 500 kilocalories more and gained about a pound per
week when they were eating processed foods. This study design could show causation, not just
correlation, because the other nutritional factors like calories, sugar, fat, fiber, and
macronutrients were held constant, and the diets were tested in the same people, so other
factors such as genetics, sleep, stress, and exercise were constant between the two types of
diets. (This was an example of a crossover randomized controlled trial, in which each subject
serves as their own control, and they completed the processed and unprocessed phases of the
trial in random order.)
Figure 2.6. At left, researchers Kevin Hall and Stephanie Chung talk with one of the processed
foods trial participants at the NIH Clinical Center, an inpatient facility where participants lived
for the duration of the study. At right, an NIH worker prepares meals for participants in the
center’s kitchen. All meals were provided for study participants to carefully control their diet
during the trial.
This study suggested something very important—that food processing causes people to eat
more food and gain weight. However, even the best study design has limitations. For one thing,
this study was small (just 20 participants), and it only lasted for two
1.10.3 49297 weeks, so we don’t know if the findings apply to the general population over
a lifetime of complex, ever-changing diets. The next steps will be to try to repeat the study in
another group of people to see if the finding holds and to design studies to figure out why
processed foods cause increased caloric intake.
As you evaluate nutrition research, especially observational studies, keep in mind the inherent
challenges of nutrition research and look for randomized controlled trials that can help solve
those challenges. Even for randomized controlled trials, consider their limitations, and know that
one study is never enough to fully answer a question in the complex field of nutrition.
Industry Influence: Follow the Money
Understanding how diet influences health is a pressing need. By some estimates, a suboptimal
diet is the single greatest changeable risk factor contributing to death and disability worldwide,
and in the United States, the cost of diet-related chronic diseases are estimated to be as high
as $1 trillion each year.5 Yet, for all its importance, nutrition science has long suffered from a
lack of government investment, with only about 5 percent of the National Institutes of Health
(NIH) budget, or $1.8 billion, directed towards research on how the foods we eat affect our
health, according to a 2019 investigation by Politico. “In 2018, NIH funding for cancer, which
affects just under 9 percent of the population, was $6.3 billion. Funding for obesity, which
affects about 30 percent of the country, was about $1 billion,” the article noted.6
With so little government funding for nutrition science, who is funding the rest of the studies
that feed the constant news cycle? Many are funded by food companies and industry groups,
either to conduct studies in their own research divisions or in the form of grants given to
university scientists. That’s problematic, because food companies and industry groups have an
inherent bias or conflict of interest. Their primary goal is to promote their products and to sell
more of them—not to advance knowledge of food and health—and this affects how they frame
research questions, design and interpret studies, and report their results.
Marion Nestle, a retired nutrition professor at New York University, has written extensively
about this problem. For a year in 2015-2016, she informally tracked industry-funded studies and
found that 90 percent of the time, their conclusions benefited the industry that funded them. In
another example, a 2013 meta-analysis found that among studies that looked at whether soda
consumption contributed to obesity, those funded by the soda industry were five times more
likely to conclude that it doesn’t contribute to obesity compared to those not funded by the
industry.7 (Consider the processed foods RCT we just discussed. It was funded by the National
Institutes of Health, which doesn’t have a stake in the results. Would you trust the results of a
study of processed foods if it was funded by Nabisco? Or for that matter, the Broccoli Growers
of America? Probably not.)
There’s likely a long history of biased nutrition research influencing dietary advice. For example,
in the 1960s, the sugar industry paid well-respected academic scientists to publish research
concluding that it was fat—not sugar—that was detrimental to heart health.8 (Both too much
fat and too much sugar can negatively affect heart health, but it benefited the sugar industry to
focus the blame on fat.) As recently as 2015, Coca-Cola was funding research meant to
promote lack of physical activity as the main cause of obesity, shifting blame away from dietary
factors, such as drinking soda.9 When food companies drive the narrative coming out of
nutrition research, this can potentially impact public policy.
Media attention has made researchers and policy makers much more aware of the problems
with industry funding and conflicts of interest in nutrition research, and they’re working to solve
them. But regardless, if you see reports of a study that shows that blueberries can block
bladder infections, pistachios can prevent pancreatitis, or cinnamon can cure cancer… well, you
should be skeptical, and always check the funding source. Studies on a single type of food are
almost always industry-funded.
It turns out that there has been a randomized controlled trial of processed foods and weight
gain. It was funded by the National Institutes of Health and published in 2019 in the journal Cell
Metabolism.4 In this study, 20 participants lived in the NIH’s Clinical Center for one month,
where they consumed only processed foods for two weeks and only unprocessed foods for
another two weeks, and they could eat as much or as little as they liked during each of these
periods. The diets were carefully designed by dietitians so that they were matched in calories,
sugar, fat, fiber, and macronutrients, and the exact amounts consumed by the participants
were measured every day (solving the problem of measuring diet complexity and accurately
describing what and how much people eat every day).
The study found that people ate about 500 kilocalories more and gained about a pound per
week when they were eating processed foods. This study design could show causation, not just
correlation, because the other nutritional factors like calories, sugar, fat, fiber, and
macronutrients were held constant, and the diets were tested in the same people, so other
factors such as genetics, sleep, stress, and exercise were constant between the two types of
diets. (This was an example of a crossover randomized controlled trial, in which each subject
serves as their own control, and they completed the processed and unprocessed phases of the
trial in random order.)
Figure 2.6. At left, researchers Kevin Hall and Stephanie Chung talk with one of the processed
foods trial participants at the NIH Clinical Center, an inpatient facility where participants lived
for the duration of the study. At right, an NIH worker prepares meals for participants in the
center’s kitchen. All meals were provided for study participants to carefully control their diet
during the trial.
This study suggested something very important—that food processing causes people to eat
more food and gain weight. However, even the best study design has limitations. For one thing,
this study was small (just 20 participants), and it only lasted for two
1.10.3 49297 weeks, so we don’t know if the findings apply to the general population over
a lifetime of complex, ever-changing diets. The next steps will be to try to repeat the study in
another group of people to see if the finding holds and to design studies to figure out why
processed foods cause increased caloric intake.
As you evaluate nutrition research, especially observational studies, keep in mind the inherent
challenges of nutrition research and look for randomized controlled trials that can help solve
those challenges. Even for randomized controlled trials, consider their limitations, and know that
one study is never enough to fully answer a question in the complex field of nutrition.
Industry Influence: Follow the Money
Understanding how diet influences health is a pressing need. By some estimates, a suboptimal
diet is the single greatest changeable risk factor contributing to death and disability worldwide,
and in the United States, the cost of diet-related chronic diseases are estimated to be as high
as $1 trillion each year.5 Yet, for all its importance, nutrition science has long suffered from a
lack of government investment, with only about 5 percent of the National Institutes of Health
(NIH) budget, or $1.8 billion, directed towards research on how the foods we eat affect our
health, according to a 2019 investigation by Politico. “In 2018, NIH funding for cancer, which
affects just under 9 percent of the population, was $6.3 billion. Funding for obesity, which
affects about 30 percent of the country, was about $1 billion,” the article noted.6
With so little government funding for nutrition science, who is funding the rest of the studies
that feed the constant news cycle? Many are funded by food companies and industry groups,
either to conduct studies in their own research divisions or in the form of grants given to
university scientists. That’s problematic, because food companies and industry groups have an
inherent bias or conflict of interest. Their primary goal is to promote their products and to sell
more of them—not to advance knowledge of food and health—and this affects how they frame
research questions, design and interpret studies, and report their results.
Marion Nestle, a retired nutrition professor at New York University, has written extensively
about this problem. For a year in 2015-2016, she informally tracked industry-funded studies and
found that 90 percent of the time, their conclusions benefited the industry that funded them. In
another example, a 2013 meta-analysis found that among studies that looked at whether soda
consumption contributed to obesity, those funded by the soda industry were five times more
likely to conclude that it doesn’t contribute to obesity compared to those not funded by the
industry.7 (Consider the processed foods RCT we just discussed. It was funded by the National
Institutes of Health, which doesn’t have a stake in the results. Would you trust the results of a
study of processed foods if it was funded by Nabisco? Or for that matter, the Broccoli Growers
of America? Probably not.)
There’s likely a long history of biased nutrition research influencing dietary advice. For example,
in the 1960s, the sugar industry paid well-respected academic scientists to publish research
concluding that it was fat—not sugar—that was detrimental to heart health.8 (Both too much
fat and too much sugar can negatively affect heart health, but it benefited the sugar industry to
focus the blame on fat.) As recently as 2015, Coca-Cola was funding research meant to
promote lack of physical activity as the main cause of obesity, shifting blame away from dietary
factors, such as drinking soda.9 When food companies drive the narrative coming out of
nutrition research, this can potentially impact public policy.
Media attention has made researchers and policy makers much more aware of the problems
with industry funding and conflicts of interest in nutrition research, and they’re working to solve
them. But regardless, if you see reports of a study that shows that blueberries can block
bladder infections, pistachios can prevent pancreatitis, or cinnamon can cure cancer… well, you
should be skeptical, and always check the funding source. Studies on a single type of food are
almost always industry-funded.
It turns out that there has been a randomized controlled trial of processed foods and weight
gain. It was funded by the National Institutes of Health and published in 2019 in the journal Cell
Metabolism.4 In this study, 20 participants lived in the NIH’s Clinical Center for one month,
where they consumed only processed foods for two weeks and only unprocessed foods for
another two weeks, and they could eat as much or as little as they liked during each of these
periods. The diets were carefully designed by dietitians so that they were matched in calories,
sugar, fat, fiber, and macronutrients, and the exact amounts consumed by the participants
were measured every day (solving the problem of measuring diet complexity and accurately
describing what and how much people eat every day).
The study found that people ate about 500 kilocalories more and gained about a pound per
week when they were eating processed foods. This study design could show causation, not just
correlation, because the other nutritional factors like calories, sugar, fat, fiber, and
macronutrients were held constant, and the diets were tested in the same people, so other
factors such as genetics, sleep, stress, and exercise were constant between the two types of
diets. (This was an example of a crossover randomized controlled trial, in which each subject
serves as their own control, and they completed the processed and unprocessed phases of the
trial in random order.)
Figure 2.6. At left, researchers Kevin Hall and Stephanie Chung talk with one of the processed
foods trial participants at the NIH Clinical Center, an inpatient facility where participants lived
for the duration of the study. At right, an NIH worker prepares meals for participants in the
center’s kitchen. All meals were provided for study participants to carefully control their diet
during the trial.
This study suggested something very important—that food processing causes people to eat
more food and gain weight. However, even the best study design has limitations. For one thing,
this study was small (just 20 participants), and it only lasted for two
1.10.3 49297 weeks, so we don’t know if the findings apply to the general population over
a lifetime of complex, ever-changing diets. The next steps will be to try to repeat the study in
another group of people to see if the finding holds and to design studies to figure out why
processed foods cause increased caloric intake.
As you evaluate nutrition research, especially observational studies, keep in mind the inherent
challenges of nutrition research and look for randomized controlled trials that can help solve
those challenges. Even for randomized controlled trials, consider their limitations, and know that
one study is never enough to fully answer a question in the complex field of nutrition.
Industry Influence: Follow the Money
Understanding how diet influences health is a pressing need. By some estimates, a suboptimal
diet is the single greatest changeable risk factor contributing to death and disability worldwide,
and in the United States, the cost of diet-related chronic diseases are estimated to be as high
as $1 trillion each year.5 Yet, for all its importance, nutrition science has long suffered from a
lack of government investment, with only about 5 percent of the National Institutes of Health
(NIH) budget, or $1.8 billion, directed towards research on how the foods we eat affect our
health, according to a 2019 investigation by Politico. “In 2018, NIH funding for cancer, which
affects just under 9 percent of the population, was $6.3 billion. Funding for obesity, which
affects about 30 percent of the country, was about $1 billion,” the article noted.6
With so little government funding for nutrition science, who is funding the rest of the studies
that feed the constant news cycle? Many are funded by food companies and industry groups,
either to conduct studies in their own research divisions or in the form of grants given to
university scientists. That’s problematic, because food companies and industry groups have an
inherent bias or conflict of interest. Their primary goal is to promote their products and to sell
more of them—not to advance knowledge of food and health—and this affects how they frame
research questions, design and interpret studies, and report their results.
Marion Nestle, a retired nutrition professor at New York University, has written extensively
about this problem. For a year in 2015-2016, she informally tracked industry-funded studies and
found that 90 percent of the time, their conclusions benefited the industry that funded them. In
another example, a 2013 meta-analysis found that among studies that looked at whether soda
consumption contributed to obesity, those funded by the soda industry were five times more
likely to conclude that it doesn’t contribute to obesity compared to those not funded by the
industry.7 (Consider the processed foods RCT we just discussed. It was funded by the National
Institutes of Health, which doesn’t have a stake in the results. Would you trust the results of a
study of processed foods if it was funded by Nabisco? Or for that matter, the Broccoli Growers
of America? Probably not.)
There’s likely a long history of biased nutrition research influencing dietary advice. For example,
in the 1960s, the sugar industry paid well-respected academic scientists to publish research
concluding that it was fat—not sugar—that was detrimental to heart health.8 (Both too much
fat and too much sugar can negatively affect heart health, but it benefited the sugar industry to
focus the blame on fat.) As recently as 2015, Coca-Cola was funding research meant to
promote lack of physical activity as the main cause of obesity, shifting blame away from dietary
factors, such as drinking soda.9 When food companies drive the narrative coming out of
nutrition research, this can potentially impact public policy.
Media attention has made researchers and policy makers much more aware of the problems
with industry funding and conflicts of interest in nutrition research, and they’re working to solve
them. But regardless, if you see reports of a study that shows that blueberries can block
bladder infections, pistachios can prevent pancreatitis, or cinnamon can cure cancer… well, you
should be skeptical, and always check the funding source. Studies on a single type of food are
almost always industry-funded.
It turns out that there has been a randomized controlled trial of processed foods and weight
gain. It was funded by the National Institutes of Health and published in 2019 in the journal Cell
Metabolism.4 In this study, 20 participants lived in the NIH’s Clinical Center for one month,
where they consumed only processed foods for two weeks and only unprocessed foods for
another two weeks, and they could eat as much or as little as they liked during each of these
periods. The diets were carefully designed by dietitians so that they were matched in calories,
sugar, fat, fiber, and macronutrients, and the exact amounts consumed by the participants
were measured every day (solving the problem of measuring diet complexity and accurately
describing what and how much people eat every day).
The study found that people ate about 500 kilocalories more and gained about a pound per
week when they were eating processed foods. This study design could show causation, not just
correlation, because the other nutritional factors like calories, sugar, fat, fiber, and
macronutrients were held constant, and the diets were tested in the same people, so other
factors such as genetics, sleep, stress, and exercise were constant between the two types of
diets. (This was an example of a crossover randomized controlled trial, in which each subject
serves as their own control, and they completed the processed and unprocessed phases of the
trial in random order.)
Figure 2.6. At left, researchers Kevin Hall and Stephanie Chung talk with one of the processed
foods trial participants at the NIH Clinical Center, an inpatient facility where participants lived
for the duration of the study. At right, an NIH worker prepares meals for participants in the
center’s kitchen. All meals were provided for study participants to carefully control their diet
during the trial.
This study suggested something very important—that food processing causes people to eat
more food and gain weight. However, even the best study design has limitations. For one thing,
this study was small (just 20 participants), and it only lasted for two
1.10.3 49297 weeks, so we don’t know if the findings apply to the general population over
a lifetime of complex, ever-changing diets. The next steps will be to try to repeat the study in
another group of people to see if the finding holds and to design studies to figure out why
processed foods cause increased caloric intake.
As you evaluate nutrition research, especially observational studies, keep in mind the inherent
challenges of nutrition research and look for randomized controlled trials that can help solve
those challenges. Even for randomized controlled trials, consider their limitations, and know that
one study is never enough to fully answer a question in the complex field of nutrition.
Industry Influence: Follow the Money
Understanding how diet influences health is a pressing need. By some estimates, a suboptimal
diet is the single greatest changeable risk factor contributing to death and disability worldwide,
and in the United States, the cost of diet-related chronic diseases are estimated to be as high
as $1 trillion each year.5 Yet, for all its importance, nutrition science has long suffered from a
lack of government investment, with only about 5 percent of the National Institutes of Health
(NIH) budget, or $1.8 billion, directed towards research on how the foods we eat affect our
health, according to a 2019 investigation by Politico. “In 2018, NIH funding for cancer, which
affects just under 9 percent of the population, was $6.3 billion. Funding for obesity, which
affects about 30 percent of the country, was about $1 billion,” the article noted.6
With so little government funding for nutrition science, who is funding the rest of the studies
that feed the constant news cycle? Many are funded by food companies and industry groups,
either to conduct studies in their own research divisions or in the form of grants given to
university scientists. That’s problematic, because food companies and industry groups have an
inherent bias or conflict of interest. Their primary goal is to promote their products and to sell
more of them—not to advance knowledge of food and health—and this affects how they frame
research questions, design and interpret studies, and report their results.
Marion Nestle, a retired nutrition professor at New York University, has written extensively
about this problem. For a year in 2015-2016, she informally tracked industry-funded studies and
found that 90 percent of the time, their conclusions benefited the industry that funded them. In
another example, a 2013 meta-analysis found that among studies that looked at whether soda
consumption contributed to obesity, those funded by the soda industry were five times more
likely to conclude that it doesn’t contribute to obesity compared to those not funded by the
industry.7 (Consider the processed foods RCT we just discussed. It was funded by the National
Institutes of Health, which doesn’t have a stake in the results. Would you trust the results of a
study of processed foods if it was funded by Nabisco? Or for that matter, the Broccoli Growers
of America? Probably not.)
There’s likely a long history of biased nutrition research influencing dietary advice. For example,
in the 1960s, the sugar industry paid well-respected academic scientists to publish research
concluding that it was fat—not sugar—that was detrimental to heart health.8 (Both too much
fat and too much sugar can negatively affect heart health, but it benefited the sugar industry to
focus the blame on fat.) As recently as 2015, Coca-Cola was funding research meant to
promote lack of physical activity as the main cause of obesity, shifting blame away from dietary
factors, such as drinking soda.9 When food companies drive the narrative coming out of
nutrition research, this can potentially impact public policy.
Media attention has made researchers and policy makers much more aware of the problems
with industry funding and conflicts of interest in nutrition research, and they’re working to solve
them. But regardless, if you see reports of a study that shows that blueberries can block
bladder infections, pistachios can prevent pancreatitis, or cinnamon can cure cancer… well, you
should be skeptical, and always check the funding source. Studies on a single type of food are
almost always industry-funded.
It turns out that there has been a randomized controlled trial of processed foods and weight
gain. It was funded by the National Institutes of Health and published in 2019 in the journal Cell
Metabolism.4 In this study, 20 participants lived in the NIH’s Clinical Center for one month,
where they consumed only processed foods for two weeks and only unprocessed foods for
another two weeks, and they could eat as much or as little as they liked during each of these
periods. The diets were carefully designed by dietitians so that they were matched in calories,
sugar, fat, fiber, and macronutrients, and the exact amounts consumed by the participants
were measured every day (solving the problem of measuring diet complexity and accurately
describing what and how much people eat every day).
The study found that people ate about 500 kilocalories more and gained about a pound per
week when they were eating processed foods. This study design could show causation, not just
correlation, because the other nutritional factors like calories, sugar, fat, fiber, and
macronutrients were held constant, and the diets were tested in the same people, so other
factors such as genetics, sleep, stress, and exercise were constant between the two types of
diets. (This was an example of a crossover randomized controlled trial, in which each subject
serves as their own control, and they completed the processed and unprocessed phases of the
trial in random order.)
Figure 2.6. At left, researchers Kevin Hall and Stephanie Chung talk with one of the processed
foods trial participants at the NIH Clinical Center, an inpatient facility where participants lived
for the duration of the study. At right, an NIH worker prepares meals for participants in the
center’s kitchen. All meals were provided for study participants to carefully control their diet
during the trial.
This study suggested something very important—that food processing causes people to eat
more food and gain weight. However, even the best study design has limitations. For one thing,
this study was small (just 20 participants), and it only lasted for two
1.10.3 49297 weeks, so we don’t know if the findings apply to the general population over
a lifetime of complex, ever-changing diets. The next steps will be to try to repeat the study in
another group of people to see if the finding holds and to design studies to figure out why
processed foods cause increased caloric intake.
As you evaluate nutrition research, especially observational studies, keep in mind the inherent
challenges of nutrition research and look for randomized controlled trials that can help solve
those challenges. Even for randomized controlled trials, consider their limitations, and know that
one study is never enough to fully answer a question in the complex field of nutrition.
Industry Influence: Follow the Money
Understanding how diet influences health is a pressing need. By some estimates, a suboptimal
diet is the single greatest changeable risk factor contributing to death and disability worldwide,
and in the United States, the cost of diet-related chronic diseases are estimated to be as high
as $1 trillion each year.5 Yet, for all its importance, nutrition science has long suffered from a
lack of government investment, with only about 5 percent of the National Institutes of Health
(NIH) budget, or $1.8 billion, directed towards research on how the foods we eat affect our
health, according to a 2019 investigation by Politico. “In 2018, NIH funding for cancer, which
affects just under 9 percent of the population, was $6.3 billion. Funding for obesity, which
affects about 30 percent of the country, was about $1 billion,” the article noted.6
With so little government funding for nutrition science, who is funding the rest of the studies
that feed the constant news cycle? Many are funded by food companies and industry groups,
either to conduct studies in their own research divisions or in the form of grants given to
university scientists. That’s problematic, because food companies and industry groups have an
inherent bias or conflict of interest. Their primary goal is to promote their products and to sell
more of them—not to advance knowledge of food and health—and this affects how they frame
research questions, design and interpret studies, and report their results.
Marion Nestle, a retired nutrition professor at New York University, has written extensively
about this problem. For a year in 2015-2016, she informally tracked industry-funded studies and
found that 90 percent of the time, their conclusions benefited the industry that funded them. In
another example, a 2013 meta-analysis found that among studies that looked at whether soda
consumption contributed to obesity, those funded by the soda industry were five times more
likely to conclude that it doesn’t contribute to obesity compared to those not funded by the
industry.7 (Consider the processed foods RCT we just discussed. It was funded by the National
Institutes of Health, which doesn’t have a stake in the results. Would you trust the results of a
study of processed foods if it was funded by Nabisco? Or for that matter, the Broccoli Growers
of America? Probably not.)
There’s likely a long history of biased nutrition research influencing dietary advice. For example,
in the 1960s, the sugar industry paid well-respected academic scientists to publish research
concluding that it was fat—not sugar—that was detrimental to heart health.8 (Both too much
fat and too much sugar can negatively affect heart health, but it benefited the sugar industry to
focus the blame on fat.) As recently as 2015, Coca-Cola was funding research meant to
promote lack of physical activity as the main cause of obesity, shifting blame away from dietary
factors, such as drinking soda.9 When food companies drive the narrative coming out of
nutrition research, this can potentially impact public policy.
Media attention has made researchers and policy makers much more aware of the problems
with industry funding and conflicts of interest in nutrition research, and they’re working to solve
them. But regardless, if you see reports of a study that shows that blueberries can block
bladder infections, pistachios can prevent pancreatitis, or cinnamon can cure cancer… well, you
should be skeptical, and always check the funding source. Studies on a single type of food are
almost always industry-funded.
It turns out that there has been a randomized controlled trial of processed foods and weight
gain. It was funded by the National Institutes of Health and published in 2019 in the journal Cell
Metabolism.4 In this study, 20 participants lived in the NIH’s Clinical Center for one month,
where they consumed only processed foods for two weeks and only unprocessed foods for
another two weeks, and they could eat as much or as little as they liked during each of these
periods. The diets were carefully designed by dietitians so that they were matched in calories,
sugar, fat, fiber, and macronutrients, and the exact amounts consumed by the participants
were measured every day (solving the problem of measuring diet complexity and accurately
describing what and how much people eat every day).
The study found that people ate about 500 kilocalories more and gained about a pound per
week when they were eating processed foods. This study design could show causation, not just
correlation, because the other nutritional factors like calories, sugar, fat, fiber, and
macronutrients were held constant, and the diets were tested in the same people, so other
factors such as genetics, sleep, stress, and exercise were constant between the two types of
diets. (This was an example of a crossover randomized controlled trial, in which each subject
serves as their own control, and they completed the processed and unprocessed phases of the
trial in random order.)
Figure 2.6. At left, researchers Kevin Hall and Stephanie Chung talk with one of the processed
foods trial participants at the NIH Clinical Center, an inpatient facility where participants lived
for the duration of the study. At right, an NIH worker prepares meals for participants in the
center’s kitchen. All meals were provided for study participants to carefully control their diet
during the trial.
This study suggested something very important—that food processing causes people to eat
more food and gain weight. However, even the best study design has limitations. For one thing,
this study was small (just 20 participants), and it only lasted for two
1.10.3 49297 weeks, so we don’t know if the findings apply to the general population over
a lifetime of complex, ever-changing diets. The next steps will be to try to repeat the study in
another group of people to see if the finding holds and to design studies to figure out why
processed foods cause increased caloric intake.
As you evaluate nutrition research, especially observational studies, keep in mind the inherent
challenges of nutrition research and look for randomized controlled trials that can help solve
those challenges. Even for randomized controlled trials, consider their limitations, and know that
one study is never enough to fully answer a question in the complex field of nutrition.
Industry Influence: Follow the Money
Understanding how diet influences health is a pressing need. By some estimates, a suboptimal
diet is the single greatest changeable risk factor contributing to death and disability worldwide,
and in the United States, the cost of diet-related chronic diseases are estimated to be as high
as $1 trillion each year.5 Yet, for all its importance, nutrition science has long suffered from a
lack of government investment, with only about 5 percent of the National Institutes of Health
(NIH) budget, or $1.8 billion, directed towards research on how the foods we eat affect our
health, according to a 2019 investigation by Politico. “In 2018, NIH funding for cancer, which
affects just under 9 percent of the population, was $6.3 billion. Funding for obesity, which
affects about 30 percent of the country, was about $1 billion,” the article noted.6
With so little government funding for nutrition science, who is funding the rest of the studies
that feed the constant news cycle? Many are funded by food companies and industry groups,
either to conduct studies in their own research divisions or in the form of grants given to
university scientists. That’s problematic, because food companies and industry groups have an
inherent bias or conflict of interest. Their primary goal is to promote their products and to sell
more of them—not to advance knowledge of food and health—and this affects how they frame
research questions, design and interpret studies, and report their results.
Marion Nestle, a retired nutrition professor at New York University, has written extensively
about this problem. For a year in 2015-2016, she informally tracked industry-funded studies and
found that 90 percent of the time, their conclusions benefited the industry that funded them. In
another example, a 2013 meta-analysis found that among studies that looked at whether soda
consumption contributed to obesity, those funded by the soda industry were five times more
likely to conclude that it doesn’t contribute to obesity compared to those not funded by the
industry.7 (Consider the processed foods RCT we just discussed. It was funded by the National
Institutes of Health, which doesn’t have a stake in the results. Would you trust the results of a
study of processed foods if it was funded by Nabisco? Or for that matter, the Broccoli Growers
of America? Probably not.)
There’s likely a long history of biased nutrition research influencing dietary advice. For example,
in the 1960s, the sugar industry paid well-respected academic scientists to publish research
concluding that it was fat—not sugar—that was detrimental to heart health.8 (Both too much
fat and too much sugar can negatively affect heart health, but it benefited the sugar industry to
focus the blame on fat.) As recently as 2015, Coca-Cola was funding research meant to
promote lack of physical activity as the main cause of obesity, shifting blame away from dietary
factors, such as drinking soda.9 When food companies drive the narrative coming out of
nutrition research, this can potentially impact public policy.
Media attention has made researchers and policy makers much more aware of the problems
with industry funding and conflicts of interest in nutrition research, and they’re working to solve
them. But regardless, if you see reports of a study that shows that blueberries can block
bladder infections, pistachios can prevent pancreatitis, or cinnamon can cure cancer… well, you
should be skeptical, and always check the funding source. Studies on a single type of food are
almost always industry-funded.
It turns out that there has been a randomized controlled trial of processed foods and weight
gain. It was funded by the National Institutes of Health and published in 2019 in the journal Cell
Metabolism.4 In this study, 20 participants lived in the NIH’s Clinical Center for one month,
where they consumed only processed foods for two weeks and only unprocessed foods for
another two weeks, and they could eat as much or as little as they liked during each of these
periods. The diets were carefully designed by dietitians so that they were matched in calories,
sugar, fat, fiber, and macronutrients, and the exact amounts consumed by the participants
were measured every day (solving the problem of measuring diet complexity and accurately
describing what and how much people eat every day).
The study found that people ate about 500 kilocalories more and gained about a pound per
week when they were eating processed foods. This study design could show causation, not just
correlation, because the other nutritional factors like calories, sugar, fat, fiber, and
macronutrients were held constant, and the diets were tested in the same people, so other
factors such as genetics, sleep, stress, and exercise were constant between the two types of
diets. (This was an example of a crossover randomized controlled trial, in which each subject
serves as their own control, and they completed the processed and unprocessed phases of the
trial in random order.)
Figure 2.6. At left, researchers Kevin Hall and Stephanie Chung talk with one of the processed
foods trial participants at the NIH Clinical Center, an inpatient facility where participants lived
for the duration of the study. At right, an NIH worker prepares meals for participants in the
center’s kitchen. All meals were provided for study participants to carefully control their diet
during the trial.
This study suggested something very important—that food processing causes people to eat
more food and gain weight. However, even the best study design has limitations. For one thing,
this study was small (just 20 participants), and it only lasted for two
1.10.3 49297 weeks, so we don’t know if the findings apply to the general population over
a lifetime of complex, ever-changing diets. The next steps will be to try to repeat the study in
another group of people to see if the finding holds and to design studies to figure out why
processed foods cause increased caloric intake.
As you evaluate nutrition research, especially observational studies, keep in mind the inherent
challenges of nutrition research and look for randomized controlled trials that can help solve
those challenges. Even for randomized controlled trials, consider their limitations, and know that
one study is never enough to fully answer a question in the complex field of nutrition.
Industry Influence: Follow the Money
Understanding how diet influences health is a pressing need. By some estimates, a suboptimal
diet is the single greatest changeable risk factor contributing to death and disability worldwide,
and in the United States, the cost of diet-related chronic diseases are estimated to be as high
as $1 trillion each year.5 Yet, for all its importance, nutrition science has long suffered from a
lack of government investment, with only about 5 percent of the National Institutes of Health
(NIH) budget, or $1.8 billion, directed towards research on how the foods we eat affect our
health, according to a 2019 investigation by Politico. “In 2018, NIH funding for cancer, which
affects just under 9 percent of the population, was $6.3 billion. Funding for obesity, which
affects about 30 percent of the country, was about $1 billion,” the article noted.6
With so little government funding for nutrition science, who is funding the rest of the studies
that feed the constant news cycle? Many are funded by food companies and industry groups,
either to conduct studies in their own research divisions or in the form of grants given to
university scientists. That’s problematic, because food companies and industry groups have an
inherent bias or conflict of interest. Their primary goal is to promote their products and to sell
more of them—not to advance knowledge of food and health—and this affects how they frame
research questions, design and interpret studies, and report their results.
Marion Nestle, a retired nutrition professor at New York University, has written extensively
about this problem. For a year in 2015-2016, she informally tracked industry-funded studies and
found that 90 percent of the time, their conclusions benefited the industry that funded them. In
another example, a 2013 meta-analysis found that among studies that looked at whether soda
consumption contributed to obesity, those funded by the soda industry were five times more
likely to conclude that it doesn’t contribute to obesity compared to those not funded by the
industry.7 (Consider the processed foods RCT we just discussed. It was funded by the National
Institutes of Health, which doesn’t have a stake in the results. Would you trust the results of a
study of processed foods if it was funded by Nabisco? Or for that matter, the Broccoli Growers
of America? Probably not.)
There’s likely a long history of biased nutrition research influencing dietary advice. For example,
in the 1960s, the sugar industry paid well-respected academic scientists to publish research
concluding that it was fat—not sugar—that was detrimental to heart health.8 (Both too much
fat and too much sugar can negatively affect heart health, but it benefited the sugar industry to
focus the blame on fat.) As recently as 2015, Coca-Cola was funding research meant to
promote lack of physical activity as the main cause of obesity, shifting blame away from dietary
factors, such as drinking soda.9 When food companies drive the narrative coming out of
nutrition research, this can potentially impact public policy.
Media attention has made researchers and policy makers much more aware of the problems
with industry funding and conflicts of interest in nutrition research, and they’re working to solve
them. But regardless, if you see reports of a study that shows that blueberries can block
bladder infections, pistachios can prevent pancreatitis, or cinnamon can cure cancer… well, you
should be skeptical, and always check the funding source. Studies on a single type of food are
almost always industry-funded.
It turns out that there has been a randomized controlled trial of processed foods and weight
gain. It was funded by the National Institutes of Health and published in 2019 in the journal Cell
Metabolism.4 In this study, 20 participants lived in the NIH’s Clinical Center for one month,
where they consumed only processed foods for two weeks and only unprocessed foods for
another two weeks, and they could eat as much or as little as they liked during each of these
periods. The diets were carefully designed by dietitians so that they were matched in calories,
sugar, fat, fiber, and macronutrients, and the exact amounts consumed by the participants
were measured every day (solving the problem of measuring diet complexity and accurately
describing what and how much people eat every day).
The study found that people ate about 500 kilocalories more and gained about a pound per
week when they were eating processed foods. This study design could show causation, not just
correlation, because the other nutritional factors like calories, sugar, fat, fiber, and
macronutrients were held constant, and the diets were tested in the same people, so other
factors such as genetics, sleep, stress, and exercise were constant between the two types of
diets. (This was an example of a crossover randomized controlled trial, in which each subject
serves as their own control, and they completed the processed and unprocessed phases of the
trial in random order.)
Figure 2.6. At left, researchers Kevin Hall and Stephanie Chung talk with one of the processed
foods trial participants at the NIH Clinical Center, an inpatient facility where participants lived
for the duration of the study. At right, an NIH worker prepares meals for participants in the
center’s kitchen. All meals were provided for study participants to carefully control their diet
during the trial.
This study suggested something very important—that food processing causes people to eat
more food and gain weight. However, even the best study design has limitations. For one thing,
this study was small (just 20 participants), and it only lasted for two
1.10.3 49297 weeks, so we don’t know if the findings apply to the general population over
a lifetime of complex, ever-changing diets. The next steps will be to try to repeat the study in
another group of people to see if the finding holds and to design studies to figure out why
processed foods cause increased caloric intake.
As you evaluate nutrition research, especially observational studies, keep in mind the inherent
challenges of nutrition research and look for randomized controlled trials that can help solve
those challenges. Even for randomized controlled trials, consider their limitations, and know that
one study is never enough to fully answer a question in the complex field of nutrition.
Industry Influence: Follow the Money
Understanding how diet influences health is a pressing need. By some estimates, a suboptimal
diet is the single greatest changeable risk factor contributing to death and disability worldwide,
and in the United States, the cost of diet-related chronic diseases are estimated to be as high
as $1 trillion each year.5 Yet, for all its importance, nutrition science has long suffered from a
lack of government investment, with only about 5 percent of the National Institutes of Health
(NIH) budget, or $1.8 billion, directed towards research on how the foods we eat affect our
health, according to a 2019 investigation by Politico. “In 2018, NIH funding for cancer, which
affects just under 9 percent of the population, was $6.3 billion. Funding for obesity, which
affects about 30 percent of the country, was about $1 billion,” the article noted.6
With so little government funding for nutrition science, who is funding the rest of the studies
that feed the constant news cycle? Many are funded by food companies and industry groups,
either to conduct studies in their own research divisions or in the form of grants given to
university scientists. That’s problematic, because food companies and industry groups have an
inherent bias or conflict of interest. Their primary goal is to promote their products and to sell
more of them—not to advance knowledge of food and health—and this affects how they frame
research questions, design and interpret studies, and report their results.
Marion Nestle, a retired nutrition professor at New York University, has written extensively
about this problem. For a year in 2015-2016, she informally tracked industry-funded studies and
found that 90 percent of the time, their conclusions benefited the industry that funded them. In
another example, a 2013 meta-analysis found that among studies that looked at whether soda
consumption contributed to obesity, those funded by the soda industry were five times more
likely to conclude that it doesn’t contribute to obesity compared to those not funded by the
industry.7 (Consider the processed foods RCT we just discussed. It was funded by the National
Institutes of Health, which doesn’t have a stake in the results. Would you trust the results of a
study of processed foods if it was funded by Nabisco? Or for that matter, the Broccoli Growers
of America? Probably not.)
There’s likely a long history of biased nutrition research influencing dietary advice. For example,
in the 1960s, the sugar industry paid well-respected academic scientists to publish research
concluding that it was fat—not sugar—that was detrimental to heart health.8 (Both too much
fat and too much sugar can negatively affect heart health, but it benefited the sugar industry to
focus the blame on fat.) As recently as 2015, Coca-Cola was funding research meant to
promote lack of physical activity as the main cause of obesity, shifting blame away from dietary
factors, such as drinking soda.9 When food companies drive the narrative coming out of
nutrition research, this can potentially impact public policy.
Media attention has made researchers and policy makers much more aware of the problems
with industry funding and conflicts of interest in nutrition research, and they’re working to solve
them. But regardless, if you see reports of a study that shows that blueberries can block
bladder infections, pistachios can prevent pancreatitis, or cinnamon can cure cancer… well, you
should be skeptical, and always check the funding source. Studies on a single type of food are
almost always industry-funded.
It turns out that there has been a randomized controlled trial of processed foods and weight
gain. It was funded by the National Institutes of Health and published in 2019 in the journal Cell
Metabolism.4 In this study, 20 participants lived in the NIH’s Clinical Center for one month,
where they consumed only processed foods for two weeks and only unprocessed foods for
another two weeks, and they could eat as much or as little as they liked during each of these
periods. The diets were carefully designed by dietitians so that they were matched in calories,
sugar, fat, fiber, and macronutrients, and the exact amounts consumed by the participants
were measured every day (solving the problem of measuring diet complexity and accurately
describing what and how much people eat every day).
The study found that people ate about 500 kilocalories more and gained about a pound per
week when they were eating processed foods. This study design could show causation, not just
correlation, because the other nutritional factors like calories, sugar, fat, fiber, and
macronutrients were held constant, and the diets were tested in the same people, so other
factors such as genetics, sleep, stress, and exercise were constant between the two types of
diets. (This was an example of a crossover randomized controlled trial, in which each subject
serves as their own control, and they completed the processed and unprocessed phases of the
trial in random order.)
Figure 2.6. At left, researchers Kevin Hall and Stephanie Chung talk with one of the processed
foods trial participants at the NIH Clinical Center, an inpatient facility where participants lived
for the duration of the study. At right, an NIH worker prepares meals for participants in the
center’s kitchen. All meals were provided for study participants to carefully control their diet
during the trial.
This study suggested something very important—that food processing causes people to eat
more food and gain weight. However, even the best study design has limitations. For one thing,
this study was small (just 20 participants), and it only lasted for two
1.10.3 49297 weeks, so we don’t know if the findings apply to the general population over
a lifetime of complex, ever-changing diets. The next steps will be to try to repeat the study in
another group of people to see if the finding holds and to design studies to figure out why
processed foods cause increased caloric intake.
As you evaluate nutrition research, especially observational studies, keep in mind the inherent
challenges of nutrition research and look for randomized controlled trials that can help solve
those challenges. Even for randomized controlled trials, consider their limitations, and know that
one study is never enough to fully answer a question in the complex field of nutrition.
Industry Influence: Follow the Money
Understanding how diet influences health is a pressing need. By some estimates, a suboptimal
diet is the single greatest changeable risk factor contributing to death and disability worldwide,
and in the United States, the cost of diet-related chronic diseases are estimated to be as high
as $1 trillion each year.5 Yet, for all its importance, nutrition science has long suffered from a
lack of government investment, with only about 5 percent of the National Institutes of Health
(NIH) budget, or $1.8 billion, directed towards research on how the foods we eat affect our
health, according to a 2019 investigation by Politico. “In 2018, NIH funding for cancer, which
affects just under 9 percent of the population, was $6.3 billion. Funding for obesity, which
affects about 30 percent of the country, was about $1 billion,” the article noted.6
With so little government funding for nutrition science, who is funding the rest of the studies
that feed the constant news cycle? Many are funded by food companies and industry groups,
either to conduct studies in their own research divisions or in the form of grants given to
university scientists. That’s problematic, because food companies and industry groups have an
inherent bias or conflict of interest. Their primary goal is to promote their products and to sell
more of them—not to advance knowledge of food and health—and this affects how they frame
research questions, design and interpret studies, and report their results.
Marion Nestle, a retired nutrition professor at New York University, has written extensively
about this problem. For a year in 2015-2016, she informally tracked industry-funded studies and
found that 90 percent of the time, their conclusions benefited the industry that funded them. In
another example, a 2013 meta-analysis found that among studies that looked at whether soda
consumption contributed to obesity, those funded by the soda industry were five times more
likely to conclude that it doesn’t contribute to obesity compared to those not funded by the
industry.7 (Consider the processed foods RCT we just discussed. It was funded by the National
Institutes of Health, which doesn’t have a stake in the results. Would you trust the results of a
study of processed foods if it was funded by Nabisco? Or for that matter, the Broccoli Growers
of America? Probably not.)
There’s likely a long history of biased nutrition research influencing dietary advice. For example,
in the 1960s, the sugar industry paid well-respected academic scientists to publish research
concluding that it was fat—not sugar—that was detrimental to heart health.8 (Both too much
fat and too much sugar can negatively affect heart health, but it benefited the sugar industry to
focus the blame on fat.) As recently as 2015, Coca-Cola was funding research meant to
promote lack of physical activity as the main cause of obesity, shifting blame away from dietary
factors, such as drinking soda.9 When food companies drive the narrative coming out of
nutrition research, this can potentially impact public policy.
Media attention has made researchers and policy makers much more aware of the problems
with industry funding and conflicts of interest in nutrition research, and they’re working to solve
them. But regardless, if you see reports of a study that shows that blueberries can block
bladder infections, pistachios can prevent pancreatitis, or cinnamon can cure cancer… well, you
should be skeptical, and always check the funding source. Studies on a single type of food are
almost always industry-funded.
It turns out that there has been a randomized controlled trial of processed foods and weight
gain. It was funded by the National Institutes of Health and published in 2019 in the journal Cell
Metabolism.4 In this study, 20 participants lived in the NIH’s Clinical Center for one month,
where they consumed only processed foods for two weeks and only unprocessed foods for
another two weeks, and they could eat as much or as little as they liked during each of these
periods. The diets were carefully designed by dietitians so that they were matched in calories,
sugar, fat, fiber, and macronutrients, and the exact amounts consumed by the participants
were measured every day (solving the problem of measuring diet complexity and accurately
describing what and how much people eat every day).
The study found that people ate about 500 kilocalories more and gained about a pound per
week when they were eating processed foods. This study design could show causation, not just
correlation, because the other nutritional factors like calories, sugar, fat, fiber, and
macronutrients were held constant, and the diets were tested in the same people, so other
factors such as genetics, sleep, stress, and exercise were constant between the two types of
diets. (This was an example of a crossover randomized controlled trial, in which each subject
serves as their own control, and they completed the processed and unprocessed phases of the
trial in random order.)
Figure 2.6. At left, researchers Kevin Hall and Stephanie Chung talk with one of the processed
foods trial participants at the NIH Clinical Center, an inpatient facility where participants lived
for the duration of the study. At right, an NIH worker prepares meals for participants in the
center’s kitchen. All meals were provided for study participants to carefully control their diet
during the trial.
This study suggested something very important—that food processing causes people to eat
more food and gain weight. However, even the best study design has limitations. For one thing,
this study was small (just 20 participants), and it only lasted for two
1.10.3 49297 weeks, so we don’t know if the findings apply to the general population over
a lifetime of complex, ever-changing diets. The next steps will be to try to repeat the study in
another group of people to see if the finding holds and to design studies to figure out why
processed foods cause increased caloric intake.
As you evaluate nutrition research, especially observational studies, keep in mind the inherent
challenges of nutrition research and look for randomized controlled trials that can help solve
those challenges. Even for randomized controlled trials, consider their limitations, and know that
one study is never enough to fully answer a question in the complex field of nutrition.
Industry Influence: Follow the Money
Understanding how diet influences health is a pressing need. By some estimates, a suboptimal
diet is the single greatest changeable risk factor contributing to death and disability worldwide,
and in the United States, the cost of diet-related chronic diseases are estimated to be as high
as $1 trillion each year.5 Yet, for all its importance, nutrition science has long suffered from a
lack of government investment, with only about 5 percent of the National Institutes of Health
(NIH) budget, or $1.8 billion, directed towards research on how the foods we eat affect our
health, according to a 2019 investigation by Politico. “In 2018, NIH funding for cancer, which
affects just under 9 percent of the population, was $6.3 billion. Funding for obesity, which
affects about 30 percent of the country, was about $1 billion,” the article noted.6
With so little government funding for nutrition science, who is funding the rest of the studies
that feed the constant news cycle? Many are funded by food companies and industry groups,
either to conduct studies in their own research divisions or in the form of grants given to
university scientists. That’s problematic, because food companies and industry groups have an
inherent bias or conflict of interest. Their primary goal is to promote their products and to sell
more of them—not to advance knowledge of food and health—and this affects how they frame
research questions, design and interpret studies, and report their results.
Marion Nestle, a retired nutrition professor at New York University, has written extensively
about this problem. For a year in 2015-2016, she informally tracked industry-funded studies and
found that 90 percent of the time, their conclusions benefited the industry that funded them. In
another example, a 2013 meta-analysis found that among studies that looked at whether soda
consumption contributed to obesity, those funded by the soda industry were five times more
likely to conclude that it doesn’t contribute to obesity compared to those not funded by the
industry.7 (Consider the processed foods RCT we just discussed. It was funded by the National
Institutes of Health, which doesn’t have a stake in the results. Would you trust the results of a
study of processed foods if it was funded by Nabisco? Or for that matter, the Broccoli Growers
of America? Probably not.)
There’s likely a long history of biased nutrition research influencing dietary advice. For example,
in the 1960s, the sugar industry paid well-respected academic scientists to publish research
concluding that it was fat—not sugar—that was detrimental to heart health.8 (Both too much
fat and too much sugar can negatively affect heart health, but it benefited the sugar industry to
focus the blame on fat.) As recently as 2015, Coca-Cola was funding research meant to
promote lack of physical activity as the main cause of obesity, shifting blame away from dietary
factors, such as drinking soda.9 When food companies drive the narrative coming out of
nutrition research, this can potentially impact public policy.
Media attention has made researchers and policy makers much more aware of the problems
with industry funding and conflicts of interest in nutrition research, and they’re working to solve
them. But regardless, if you see reports of a study that shows that blueberries can block
bladder infections, pistachios can prevent pancreatitis, or cinnamon can cure cancer… well, you
should be skeptical, and always check the funding source. Studies on a single type of food are
almost always industry-funded.
It turns out that there has been a randomized controlled trial of processed foods and weight
gain. It was funded by the National Institutes of Health and published in 2019 in the journal Cell
Metabolism.4 In this study, 20 participants lived in the NIH’s Clinical Center for one month,
where they consumed only processed foods for two weeks and only unprocessed foods for
another two weeks, and they could eat as much or as little as they liked during each of these
periods. The diets were carefully designed by dietitians so that they were matched in calories,
sugar, fat, fiber, and macronutrients, and the exact amounts consumed by the participants
were measured every day (solving the problem of measuring diet complexity and accurately
describing what and how much people eat every day).
The study found that people ate about 500 kilocalories more and gained about a pound per
week when they were eating processed foods. This study design could show causation, not just
correlation, because the other nutritional factors like calories, sugar, fat, fiber, and
macronutrients were held constant, and the diets were tested in the same people, so other
factors such as genetics, sleep, stress, and exercise were constant between the two types of
diets. (This was an example of a crossover randomized controlled trial, in which each subject
serves as their own control, and they completed the processed and unprocessed phases of the
trial in random order.)
Figure 2.6. At left, researchers Kevin Hall and Stephanie Chung talk with one of the processed
foods trial participants at the NIH Clinical Center, an inpatient facility where participants lived
for the duration of the study. At right, an NIH worker prepares meals for participants in the
center’s kitchen. All meals were provided for study participants to carefully control their diet
during the trial.
This study suggested something very important—that food processing causes people to eat
more food and gain weight. However, even the best study design has limitations. For one thing,
this study was small (just 20 participants), and it only lasted for two
1.10.3 49297 weeks, so we don’t know if the findings apply to the general population over
a lifetime of complex, ever-changing diets. The next steps will be to try to repeat the study in
another group of people to see if the finding holds and to design studies to figure out why
processed foods cause increased caloric intake.
As you evaluate nutrition research, especially observational studies, keep in mind the inherent
challenges of nutrition research and look for randomized controlled trials that can help solve
those challenges. Even for randomized controlled trials, consider their limitations, and know that
one study is never enough to fully answer a question in the complex field of nutrition.
Industry Influence: Follow the Money
Understanding how diet influences health is a pressing need. By some estimates, a suboptimal
diet is the single greatest changeable risk factor contributing to death and disability worldwide,
and in the United States, the cost of diet-related chronic diseases are estimated to be as high
as $1 trillion each year.5 Yet, for all its importance, nutrition science has long suffered from a
lack of government investment, with only about 5 percent of the National Institutes of Health
(NIH) budget, or $1.8 billion, directed towards research on how the foods we eat affect our
health, according to a 2019 investigation by Politico. “In 2018, NIH funding for cancer, which
affects just under 9 percent of the population, was $6.3 billion. Funding for obesity, which
affects about 30 percent of the country, was about $1 billion,” the article noted.6
With so little government funding for nutrition science, who is funding the rest of the studies
that feed the constant news cycle? Many are funded by food companies and industry groups,
either to conduct studies in their own research divisions or in the form of grants given to
university scientists. That’s problematic, because food companies and industry groups have an
inherent bias or conflict of interest. Their primary goal is to promote their products and to sell
more of them—not to advance knowledge of food and health—and this affects how they frame
research questions, design and interpret studies, and report their results.
Marion Nestle, a retired nutrition professor at New York University, has written extensively
about this problem. For a year in 2015-2016, she informally tracked industry-funded studies and
found that 90 percent of the time, their conclusions benefited the industry that funded them. In
another example, a 2013 meta-analysis found that among studies that looked at whether soda
consumption contributed to obesity, those funded by the soda industry were five times more
likely to conclude that it doesn’t contribute to obesity compared to those not funded by the
industry.7 (Consider the processed foods RCT we just discussed. It was funded by the National
Institutes of Health, which doesn’t have a stake in the results. Would you trust the results of a
study of processed foods if it was funded by Nabisco? Or for that matter, the Broccoli Growers
of America? Probably not.)
There’s likely a long history of biased nutrition research influencing dietary advice. For example,
in the 1960s, the sugar industry paid well-respected academic scientists to publish research
concluding that it was fat—not sugar—that was detrimental to heart health.8 (Both too much
fat and too much sugar can negatively affect heart health, but it benefited the sugar industry to
focus the blame on fat.) As recently as 2015, Coca-Cola was funding research meant to
promote lack of physical activity as the main cause of obesity, shifting blame away from dietary
factors, such as drinking soda.9 When food companies drive the narrative coming out of
nutrition research, this can potentially impact public policy.
Media attention has made researchers and policy makers much more aware of the problems
with industry funding and conflicts of interest in nutrition research, and they’re working to solve
them. But regardless, if you see reports of a study that shows that blueberries can block
bladder infections, pistachios can prevent pancreatitis, or cinnamon can cure cancer… well, you
should be skeptical, and always check the funding source. Studies on a single type of food are
almost always industry-funded.
It turns out that there has been a randomized controlled trial of processed foods and weight
gain. It was funded by the National Institutes of Health and published in 2019 in the journal Cell
Metabolism.4 In this study, 20 participants lived in the NIH’s Clinical Center for one month,
where they consumed only processed foods for two weeks and only unprocessed foods for
another two weeks, and they could eat as much or as little as they liked during each of these
periods. The diets were carefully designed by dietitians so that they were matched in calories,
sugar, fat, fiber, and macronutrients, and the exact amounts consumed by the participants
were measured every day (solving the problem of measuring diet complexity and accurately
describing what and how much people eat every day).
The study found that people ate about 500 kilocalories more and gained about a pound per
week when they were eating processed foods. This study design could show causation, not just
correlation, because the other nutritional factors like calories, sugar, fat, fiber, and
macronutrients were held constant, and the diets were tested in the same people, so other
factors such as genetics, sleep, stress, and exercise were constant between the two types of
diets. (This was an example of a crossover randomized controlled trial, in which each subject
serves as their own control, and they completed the processed and unprocessed phases of the
trial in random order.)
Figure 2.6. At left, researchers Kevin Hall and Stephanie Chung talk with one of the processed
foods trial participants at the NIH Clinical Center, an inpatient facility where participants lived
for the duration of the study. At right, an NIH worker prepares meals for participants in the
center’s kitchen. All meals were provided for study participants to carefully control their diet
during the trial.
This study suggested something very important—that food processing causes people to eat
more food and gain weight. However, even the best study design has limitations. For one thing,
this study was small (just 20 participants), and it only lasted for two
1.10.3 49297 weeks, so we don’t know if the findings apply to the general population over
a lifetime of complex, ever-changing diets. The next steps will be to try to repeat the study in
another group of people to see if the finding holds and to design studies to figure out why
processed foods cause increased caloric intake.
As you evaluate nutrition research, especially observational studies, keep in mind the inherent
challenges of nutrition research and look for randomized controlled trials that can help solve
those challenges. Even for randomized controlled trials, consider their limitations, and know that
one study is never enough to fully answer a question in the complex field of nutrition.
Industry Influence: Follow the Money
Understanding how diet influences health is a pressing need. By some estimates, a suboptimal
diet is the single greatest changeable risk factor contributing to death and disability worldwide,
and in the United States, the cost of diet-related chronic diseases are estimated to be as high
as $1 trillion each year.5 Yet, for all its importance, nutrition science has long suffered from a
lack of government investment, with only about 5 percent of the National Institutes of Health
(NIH) budget, or $1.8 billion, directed towards research on how the foods we eat affect our
health, according to a 2019 investigation by Politico. “In 2018, NIH funding for cancer, which
affects just under 9 percent of the population, was $6.3 billion. Funding for obesity, which
affects about 30 percent of the country, was about $1 billion,” the article noted.6
With so little government funding for nutrition science, who is funding the rest of the studies
that feed the constant news cycle? Many are funded by food companies and industry groups,
either to conduct studies in their own research divisions or in the form of grants given to
university scientists. That’s problematic, because food companies and industry groups have an
inherent bias or conflict of interest. Their primary goal is to promote their products and to sell
more of them—not to advance knowledge of food and health—and this affects how they frame
research questions, design and interpret studies, and report their results.
Marion Nestle, a retired nutrition professor at New York University, has written extensively
about this problem. For a year in 2015-2016, she informally tracked industry-funded studies and
found that 90 percent of the time, their conclusions benefited the industry that funded them. In
another example, a 2013 meta-analysis found that among studies that looked at whether soda
consumption contributed to obesity, those funded by the soda industry were five times more
likely to conclude that it doesn’t contribute to obesity compared to those not funded by the
industry.7 (Consider the processed foods RCT we just discussed. It was funded by the National
Institutes of Health, which doesn’t have a stake in the results. Would you trust the results of a
study of processed foods if it was funded by Nabisco? Or for that matter, the Broccoli Growers
of America? Probably not.)
There’s likely a long history of biased nutrition research influencing dietary advice. For example,
in the 1960s, the sugar industry paid well-respected academic scientists to publish research
concluding that it was fat—not sugar—that was detrimental to heart health.8 (Both too much
fat and too much sugar can negatively affect heart health, but it benefited the sugar industry to
focus the blame on fat.) As recently as 2015, Coca-Cola was funding research meant to
promote lack of physical activity as the main cause of obesity, shifting blame away from dietary
factors, such as drinking soda.9 When food companies drive the narrative coming out of
nutrition research, this can potentially impact public policy.
Media attention has made researchers and policy makers much more aware of the problems
with industry funding and conflicts of interest in nutrition research, and they’re working to solve
them. But regardless, if you see reports of a study that shows that blueberries can block
bladder infections, pistachios can prevent pancreatitis, or cinnamon can cure cancer… well, you
should be skeptical, and always check the funding source. Studies on a single type of food are
almost always industry-funded.
It turns out that there has been a randomized controlled trial of processed foods and weight
gain. It was funded by the National Institutes of Health and published in 2019 in the journal Cell
Metabolism.4 In this study, 20 participants lived in the NIH’s Clinical Center for one month,
where they consumed only processed foods for two weeks and only unprocessed foods for
another two weeks, and they could eat as much or as little as they liked during each of these
periods. The diets were carefully designed by dietitians so that they were matched in calories,
sugar, fat, fiber, and macronutrients, and the exact amounts consumed by the participants
were measured every day (solving the problem of measuring diet complexity and accurately
describing what and how much people eat every day).
The study found that people ate about 500 kilocalories more and gained about a pound per
week when they were eating processed foods. This study design could show causation, not just
correlation, because the other nutritional factors like calories, sugar, fat, fiber, and
macronutrients were held constant, and the diets were tested in the same people, so other
factors such as genetics, sleep, stress, and exercise were constant between the two types of
diets. (This was an example of a crossover randomized controlled trial, in which each subject
serves as their own control, and they completed the processed and unprocessed phases of the
trial in random order.)
Figure 2.6. At left, researchers Kevin Hall and Stephanie Chung talk with one of the processed
foods trial participants at the NIH Clinical Center, an inpatient facility where participants lived
for the duration of the study. At right, an NIH worker prepares meals for participants in the
center’s kitchen. All meals were provided for study participants to carefully control their diet
during the trial.
This study suggested something very important—that food processing causes people to eat
more food and gain weight. However, even the best study design has limitations. For one thing,
this study was small (just 20 participants), and it only lasted for two
1.10.3 49297 weeks, so we don’t know if the findings apply to the general population over
a lifetime of complex, ever-changing diets. The next steps will be to try to repeat the study in
another group of people to see if the finding holds and to design studies to figure out why
processed foods cause increased caloric intake.
As you evaluate nutrition research, especially observational studies, keep in mind the inherent
challenges of nutrition research and look for randomized controlled trials that can help solve
those challenges. Even for randomized controlled trials, consider their limitations, and know that
one study is never enough to fully answer a question in the complex field of nutrition.
Industry Influence: Follow the Money
Understanding how diet influences health is a pressing need. By some estimates, a suboptimal
diet is the single greatest changeable risk factor contributing to death and disability worldwide,
and in the United States, the cost of diet-related chronic diseases are estimated to be as high
as $1 trillion each year.5 Yet, for all its importance, nutrition science has long suffered from a
lack of government investment, with only about 5 percent of the National Institutes of Health
(NIH) budget, or $1.8 billion, directed towards research on how the foods we eat affect our
health, according to a 2019 investigation by Politico. “In 2018, NIH funding for cancer, which
affects just under 9 percent of the population, was $6.3 billion. Funding for obesity, which
affects about 30 percent of the country, was about $1 billion,” the article noted.6
With so little government funding for nutrition science, who is funding the rest of the studies
that feed the constant news cycle? Many are funded by food companies and industry groups,
either to conduct studies in their own research divisions or in the form of grants given to
university scientists. That’s problematic, because food companies and industry groups have an
inherent bias or conflict of interest. Their primary goal is to promote their products and to sell
more of them—not to advance knowledge of food and health—and this affects how they frame
research questions, design and interpret studies, and report their results.
Marion Nestle, a retired nutrition professor at New York University, has written extensively
about this problem. For a year in 2015-2016, she informally tracked industry-funded studies and
found that 90 percent of the time, their conclusions benefited the industry that funded them. In
another example, a 2013 meta-analysis found that among studies that looked at whether soda
consumption contributed to obesity, those funded by the soda industry were five times more
likely to conclude that it doesn’t contribute to obesity compared to those not funded by the
industry.7 (Consider the processed foods RCT we just discussed. It was funded by the National
Institutes of Health, which doesn’t have a stake in the results. Would you trust the results of a
study of processed foods if it was funded by Nabisco? Or for that matter, the Broccoli Growers
of America? Probably not.)
There’s likely a long history of biased nutrition research influencing dietary advice. For example,
in the 1960s, the sugar industry paid well-respected academic scientists to publish research
concluding that it was fat—not sugar—that was detrimental to heart health.8 (Both too much
fat and too much sugar can negatively affect heart health, but it benefited the sugar industry to
focus the blame on fat.) As recently as 2015, Coca-Cola was funding research meant to
promote lack of physical activity as the main cause of obesity, shifting blame away from dietary
factors, such as drinking soda.9 When food companies drive the narrative coming out of
nutrition research, this can potentially impact public policy.
Media attention has made researchers and policy makers much more aware of the problems
with industry funding and conflicts of interest in nutrition research, and they’re working to solve
them. But regardless, if you see reports of a study that shows that blueberries can block
bladder infections, pistachios can prevent pancreatitis, or cinnamon can cure cancer… well, you
should be skeptical, and always check the funding source. Studies on a single type of food are
almost always industry-funded.
It turns out that there has been a randomized controlled trial of processed foods and weight
gain. It was funded by the National Institutes of Health and published in 2019 in the journal Cell
Metabolism.4 In this study, 20 participants lived in the NIH’s Clinical Center for one month,
where they consumed only processed foods for two weeks and only unprocessed foods for
another two weeks, and they could eat as much or as little as they liked during each of these
periods. The diets were carefully designed by dietitians so that they were matched in calories,
sugar, fat, fiber, and macronutrients, and the exact amounts consumed by the participants
were measured every day (solving the problem of measuring diet complexity and accurately
describing what and how much people eat every day).
The study found that people ate about 500 kilocalories more and gained about a pound per
week when they were eating processed foods. This study design could show causation, not just
correlation, because the other nutritional factors like calories, sugar, fat, fiber, and
macronutrients were held constant, and the diets were tested in the same people, so other
factors such as genetics, sleep, stress, and exercise were constant between the two types of
diets. (This was an example of a crossover randomized controlled trial, in which each subject
serves as their own control, and they completed the processed and unprocessed phases of the
trial in random order.)
Figure 2.6. At left, researchers Kevin Hall and Stephanie Chung talk with one of the processed
foods trial participants at the NIH Clinical Center, an inpatient facility where participants lived
for the duration of the study. At right, an NIH worker prepares meals for participants in the
center’s kitchen. All meals were provided for study participants to carefully control their diet
during the trial.
This study suggested something very important—that food processing causes people to eat
more food and gain weight. However, even the best study design has limitations. For one thing,
this study was small (just 20 participants), and it only lasted for two
1.10.3 49297 weeks, so we don’t know if the findings apply to the general population over
a lifetime of complex, ever-changing diets. The next steps will be to try to repeat the study in
another group of people to see if the finding holds and to design studies to figure out why
processed foods cause increased caloric intake.
As you evaluate nutrition research, especially observational studies, keep in mind the inherent
challenges of nutrition research and look for randomized controlled trials that can help solve
those challenges. Even for randomized controlled trials, consider their limitations, and know that
one study is never enough to fully answer a question in the complex field of nutrition.
Industry Influence: Follow the Money
Understanding how diet influences health is a pressing need. By some estimates, a suboptimal
diet is the single greatest changeable risk factor contributing to death and disability worldwide,
and in the United States, the cost of diet-related chronic diseases are estimated to be as high
as $1 trillion each year.5 Yet, for all its importance, nutrition science has long suffered from a
lack of government investment, with only about 5 percent of the National Institutes of Health
(NIH) budget, or $1.8 billion, directed towards research on how the foods we eat affect our
health, according to a 2019 investigation by Politico. “In 2018, NIH funding for cancer, which
affects just under 9 percent of the population, was $6.3 billion. Funding for obesity, which
affects about 30 percent of the country, was about $1 billion,” the article noted.6
With so little government funding for nutrition science, who is funding the rest of the studies
that feed the constant news cycle? Many are funded by food companies and industry groups,
either to conduct studies in their own research divisions or in the form of grants given to
university scientists. That’s problematic, because food companies and industry groups have an
inherent bias or conflict of interest. Their primary goal is to promote their products and to sell
more of them—not to advance knowledge of food and health—and this affects how they frame
research questions, design and interpret studies, and report their results.
Marion Nestle, a retired nutrition professor at New York University, has written extensively
about this problem. For a year in 2015-2016, she informally tracked industry-funded studies and
found that 90 percent of the time, their conclusions benefited the industry that funded them. In
another example, a 2013 meta-analysis found that among studies that looked at whether soda
consumption contributed to obesity, those funded by the soda industry were five times more
likely to conclude that it doesn’t contribute to obesity compared to those not funded by the
industry.7 (Consider the processed foods RCT we just discussed. It was funded by the National
Institutes of Health, which doesn’t have a stake in the results. Would you trust the results of a
study of processed foods if it was funded by Nabisco? Or for that matter, the Broccoli Growers
of America? Probably not.)
There’s likely a long history of biased nutrition research influencing dietary advice. For example,
in the 1960s, the sugar industry paid well-respected academic scientists to publish research
concluding that it was fat—not sugar—that was detrimental to heart health.8 (Both too much
fat and too much sugar can negatively affect heart health, but it benefited the sugar industry to
focus the blame on fat.) As recently as 2015, Coca-Cola was funding research meant to
promote lack of physical activity as the main cause of obesity, shifting blame away from dietary
factors, such as drinking soda.9 When food companies drive the narrative coming out of
nutrition research, this can potentially impact public policy.
Media attention has made researchers and policy makers much more aware of the problems
with industry funding and conflicts of interest in nutrition research, and they’re working to solve
them. But regardless, if you see reports of a study that shows that blueberries can block
bladder infections, pistachios can prevent pancreatitis, or cinnamon can cure cancer… well, you
should be skeptical, and always check the funding source. Studies on a single type of food are
almost always industry-funded.
1.10.4 Conclusion
All of this can be discouraging, but you should also know that researchers are working hard to
improve the quality of nutrition research and to interpret it honestly for the rest of us. As a
consumer of nutrition information, use a skeptical eye when you read news of the latest
nutrition research. Look for areas of consensus, where committees of experts have put their
heads together to come up with the best advice they can based on the evidence we have, such
as in the Dietary Guidelines for Americans. You’ll find that while experts in this field are often
debating the latest controversy, they also agree on a lot. As we continue on in this unit, we’ll
talk more about how to find accurate sources of information and who you can trust for
evidence-based advice in the field of nutrition.
References
1Monteiro, C. A., Moubarac, J.-C., Levy, R. B., Canella, D. S., Louzada, M. L. da C., & Cannon,
G. (2018). Household availability of ultra-processed foods and obesity in nineteen European
countries. Public Health Nutrition, 21(1), 18–26. https://doi.org/10.1017/S1368980017001379
2Mendonça, R. de D., Pimenta, A. M., Gea, A., de la Fuente-Arrillaga, C., Martinez-Gonzalez, M.
A., Lopes, A. C. S., & Bes-Rastrollo, M. (2016). Ultraprocessed food consumption and risk of
overweight and obesity: The University of Navarra Follow-Up (SUN) cohort study. The American
Journal of Clinical Nutrition, 104(5), 1433–1440. https://doi.org/10.3945/ajcn.116.135004
3Ioannidis, J. P. A. (2018). The Challenge of Reforming Nutritional Epidemiologic Research.
JAMA, 320(10), 969–970. https://doi.org/10.1001/jama.2018.11025
4Hall, K. D., Ayuketah, A., Brychta, R., Cai, H., Cassimatis, T., Chen, K. Y., Chung, S. T., Costa,
E., Courville, A., Darcey, V., Fletcher, L. A., Forde, C. G., Gharib, A. M., Guo, J., Howard, R.,
Joseph, P. V., McGehee, S., Ouwerkerk, R., Raisinger, K., … Zhou, M. (2019). Ultra-Processed
Diets Cause Excess Calorie Intake and Weight Gain:
