Module 8
Weight, Body Composition, Disordered Eating, and Life-long Fitness
A. Understanding Weight and Body Composition
Body composition and body weight are related to performance, appearance,
and health. Body composition, particularly the relative amount of muscle mass, has
the potential to positively impact exercise and performance. Weight and body
composition may have a substantial impact on performance in certain sports, but may
play a much lesser role in others. In some sports body weight must be certified before
the athlete can participate in that day's competition, and the focus, at least temporarily,
is achieving a particular scale weight. Body composition and weight also influence
body image, and the desire to attain a particular body image or weight can be a
powerful motivator. An excessive or rapid loss of body weight can produce harmful
medical consequences in otherwise healthy individuals. Excess body fat, especially fat
that accumulates deep in the abdominal cavity, may influence the onset or progression
of chronic diseases and long-term health. Keeping all three areas in mind—
performance, appearance, and health—helps athletes maintain the proper perspective
when setting body weight and composition goals.
Body weight and composition have an impact on performance and are critical
factors in many sports. In sports in which judging of performance is subjective and
influenced by appearance, such as women’s figure skating, a low body weight may be
beneficial. Some athletes naturally have a low body weight, but others find
themselves using dangerous practices, such as voluntary starvation and dehydration,
to reach what they believe is a desirable weight. In acrobatic sports, such as
gymnastics and figure skating, a high power-to-weight ratio is desirable. In other
words, it is beneficial to have a relatively high percentage of skeletal muscle to
produce force, but at a minimal body weight since excess body fat contributes to total
weight but not muscle power. The establishment of a safe minimum body weight is
important and must take into account the athlete’s current amount of muscle mass,
frame size, genetic predisposition to leanness or fatness, and biologically comfortable
weight range. Attaining too low of a body weight can come at a cost to both
performance and health—reduction of muscle mass, loss of body water, loss of bone
mineral density, and initiation of disordered eating behaviors.
Aside from performance-related reasons, appearance may motivate athletes to
make body composition changes. Athletes who achieve a body composition that is
held in high esteem by society (such as, lean and muscular, thin and prepubescent)
receive praise and positive reinforcement. For some, self-esteem is closely tied to
body image, and thus body weight or composition. For these individuals, changes in
body composition, especially increases in body fat, may be a source of great concern
and unwanted media attention.
The human body is composed of an extraordinary variety of different types of
cells and materials. Because they are so numerous, these components are often
grouped into more general categories for their study and discussion. In the fields of
exercise physiology and sports nutrition, body composition is often subdivided into
the broad categories of fat mass and fat-free mass. Fat mass is all of the fat material in
the body, and fatfree mass is composed of all other tissues in the body that are not fat,
the most prominent nonfat tissue being skeletal muscle. Athletes are also interested in
the ratio of fat mass to total body mass, which may be expressed as percent body fat.
The weight of the body is also a factor, particularly in sports with weight categories.
Of primary importance are the specific components of body tissues—total
body mass (weight), body fat (fat mass), muscle mass, bone mass and density, and
fluids. The term mass is often used interchangeably with weight, but technically they
are not the same. Mass is the term that describes the amount of matter or material that
makes up an object, whereas weight is an expression of the force that is exerted by
that object due to gravity. To illustrate the difference, consider the mass and weight of
astronauts during a space mission. They have the same body mass in space as they do
on Earth, but they “weigh” much less in space due to the greatly reduced force of
gravity. Because the difference on Earth is minute, the terms mass and weight are
used interchangeably in this text. Other terms commonly used are defined in Spotlight
on...Understanding Body Composition Terminology.
Both for athletes and for the general public, the most common distinction in
body composition is body fat. Fat in the body is typically categorized as essential or
storage fat. Essential fat is the minimum amount of body fat necessary for proper
physiological functioning and is estimated to be approximately 3 percent of body
weight for males and 12 percent of body weight for females. Of the 12 percent,
approximately 9 percent is considered sex-specific fat, the fat necessary for proper
hormonal and reproductive functions. When compared to male athletes in similar
sports, females typically have a higher percentage of body fat than their male
counterparts. For example, both male and female bodybuilders are extremely lean;
however, the leanest elite female bodybuilders will have a greater percent of body fat
than the leanest elite male bodybuilders simply because of the differences in gender.
Although athletes are interested in body fat, they are also concerned about fat-
free mass or the tissues in the body that are not fat. Fat-free mass includes muscle,
bone, fluids, and organs. In particular, athletes focus on muscle mass. As with body
fat, estimating only muscle mass is difficult, so it is more common to estimate lean
body mass (LBM). LBM refers to the total amount of all physiologically necessary
tissue in the body and includes fat-free mass and essential body fat. In everyday
language, the term muscle mass is interchanged with the term lean body mass (for
example, “strength training results in an increase in LBM”), but muscle is only one
component of lean body mass. Body composition discussions usually focus on body
fat and muscle mass, and these two components will be the focus of this chapter.
B. Assessment and Interpretation of Weight and Body Composition
To understand weight and body composition, one must understand the
techniques used to estimate them and the errors that result from any type of
measurement. Weight or body composition measures are meaningless if accurate
procedures are not used. A detailed discussion of the exact procedures involved with
each method is beyond the scope of this text, and good reviews can be read in a
number of fitness assessment resources (Thompson, Gordon, and Pescatello, 2009;
Nieman, 2007). Even when the procedure is performed correctly, the results can be
misinterpreted if the standard error of the estimate is not considered. The purpose of
this section is to enable students in sports-related fields to acquire a practical, working
knowledge of this potentially confusing subject with a strong understanding of the
appropriate use and limitations of body composition assessment.
A balance beam scale or a digital scale should be used to determine body
weight (Figure 11.3). To ensure accuracy, the scale should be calibrated monthly or
quarterly, as well as any time it has been moved. Scale weight should be taken as soon
as the individual is awake, after emptying the bladder, and before any food or drink is
consumed. On a balance beam scale, weight should be recorded to the nearest 0.5 lb
or 0.2 kg (Modlesky, 2006). Home scales are convenient but most lack the accuracy
of a balance beam scale. Repeated scale weights (for example, daily, weekly) should
be taken on the same scale under similar conditions (for example, time of day).
There are a variety of methods available to determine body composition, each
with advantages and disadvantages (Table 11.1). Some of the factors that must be
considered with any method are the accuracy or precision of measurement,
practicality, ease of use, time required to obtain the measurement, cost, portability,
comfort, effort required by the subject, and training required of the technician.
Accuracy is the most important element, but some of the most accurate measurement
technologies cannot be used outside a research setting. Methods with lesser accuracy
are sometimes used for practical reasons. Some easyto-use methods are practical, but
their accuracy is low and they may give athletes a false picture of their true body
composition. In some cases the accuracy is so low the estimate is essentially
meaningless.
Because the only true measurement of the amount of fat in the body is by
chemical analysis of cadavers, all current approaches to determining body
composition estimate or predict body fat from some other measurement. Therefore, all
of these methods are indirect determinations and will have some builtin or inherent
error. In addition, there is potential for technical error in the assessment method itself.
It is extremely important to understand the potential for these errors and how they
might affect body composition results and recommendations based on those results.
The SEE for percent body fat determined from underwater weighing is
approximately +2.7 percent (Lohman, 1992). This means that if percent body fat is
determined as accurately as possible by the underwa- ter weighing technique for a
group of people, it is likely that the result obtained will be within a range that is 2.7
percent above or below the figure determined for two-thirds of the people measured.
In other words, even if this technique is performed flawlessly, a person whose body
fat result by underwater weighing is determined to be 15 percent may actually have
body fat as high as 17.7 percent or as low as 12.3 percent. Out of a group of 100
people with a body fat estimate of 15 percent, 67 will actually have a percentage of
body fat within the range of 12.3-17.7 percent. Although this is a fairly large range,
one also must be aware that the remaining one-third of the group, or 33 people, are
likely to have their “real” body fat percentage be even further outside the +2.7 percent
range.
One approach to estimating body composition is by determining the overall
density of the body. Fat tissue has a lower density (0.9 g/ml) than other tissues, so
theoretically the less dense a person’s body is the more body fat is present. How is
body density determined? Body density can be calculated as the ratio of body mass
(weight) to body volume. Mass (weight) is easily measured on a scale, but what about
volume? Archimedes’ principle is used by two techniques to determine body volume
and density.
Underwater weighing is a technique of estimating body composition that has
been utilized for decades and may be the most accurate method available to many
athletes for determining body fat. Mass can be determined easily by measuring the
person’s weight, and density can be calculated if the body’s volume is known (Figure
11.4). Submersion in water can be used to determine volume, either by the amount of
water that is displaced (for example, water rising as one slips into the bathtub) or by
determining the buoyant force acting on the submerged object. In the human body,
two things are less dense than water and act to help the body float—air and fat. In
underwater weighing, the air is accounted _ for by having the subject exhale as much
air from the lungs as possible (down to residual volume) and by accounting for the
residual volume in the prediction equation. A person that has more body fat will float
more readily (that is, have a greater buoyant force) and will therefore have a larger
volume and a lower density. Conversely, a person of the same weight with less body
fat and more muscle will tend to sink more easily (that is, have less buoyant force),
exhibiting a smaller body volume and higher density. Higher body density is
associated with lower body fat.
Due to the problems associated with using underwater weighing to determine
body volume and density, plethysmography (displacement of air to determine body
volume) was developed. The subject sits in an airtight enclosure (Figure 11.6) while
the amount of air displaced by the subject’s body is sensed by a special diaphragm
and pressure transducer. Once the body volume is determined, body density can be
calculated and body fat estimated.
A certain proportion of fat in the body is stored subcutaneously (under the
skin). Body composition that is estimated from skinfold thickness is based on the
assumption that a measurement of the thickness of the subcutaneous fat layer is
directly related to the total amount of fat in the body. A skinfold thickness may be
determined by pinching a fold of skin and measuring with calipers (Figure 11.7). Just
one site may be used, but the sum of several different sites (two, three, and seven sites
are frequently measured) is more accurate. Common sites used with men are chest,
abdomen, and thigh whereas sites used with females are typically triceps, suprailium,
and thigh. Most commonly used skinfold prediction equations have been derived
using body density or body fat determined from underwater weighing, which means
this method of estimation is twice removed from the original body density and fat
measurements.
The bioelectrical impedance analysis (BIA) body composition methodology is
based upon the rationale that body tissues can be distinguished based upon their
relative ability to conduct electrical currents. Water and tissues containing a high
proportion of water conduct electrical currents easily, whereas tissues that contain
little water, such as fat, impede the flow of electrical currents. With this method, a
nonharmful electrical current is conducted through the body and the impedance to the
flow of that current is measured (Figure 11.8). Body composition is not measured
directly; rather, an algorithm or prediction equation is used to predict body
composition from a three-compartment model: fat mass, fat-free mass, and body
water. These algorithms or equations are generally proprietary (private) to the
company that has developed them so it is difficult to conduct independent scientific
studies of the formulas.
Near-infrared interactance (NIR) is based upon the ability of different tissues
to absorb or reflect light. A wand that emits and senses near-infrared light is placed
over a body part such as the belly or center of the biceps. A light beam is directed into
the tissue, some of which is absorbed and some of which is reflected back and is
measured by spectroscopy in the wand. Less-dense tissue absorbs more near-infrared
light and more-dense tissue reflects more light back to the sensor. The differential
absorption and reflection of the near-infrared light are used in prediction equations to
estimate percent body fat. Similar to bioelectrical impedance, body composition is not
measured directly.
Dual-energy X-ray absorptiometry (DEXA or DXA) is a method that uses
low-intensity, focused X-rays to scan the body for determination of bone mineral
density and content. Originally developed for clinical use for measuring loss of bone
density, the bone mineral information can also be used as part of a threecompartment
model for estimating body composition. The potential exists for this to be a precise
method for body composition determination because it accounts for one of the tissue
compartments that can vary substantially between people and within an individual
over a lifetime.
In this procedure, the subject lies motionless on the scanning table for a few
minutes while a full body scan is performed, yielding both skeletal and soft tissue
images (Figure 11.9). Based upon proprietary algorithms developed by each company,
body composition is determined, with estimates of bone mass, fat mass, and fat-free
mass provided. Some software programs use anatomical landmarks to digitally
section the body into segments for analysis of regional body composition (for
example, trunk, arms, and legs).
Because of the expense of the equipment and the associated radiation safety
requirements, DEXA is a method of body composition assessment that is not likely to
be found outside specialized clinical facilities, research laboratories, or doctors’
offices. The equipment also contains an X-ray-generating device, and is therefore
subject to state or local licensing and safety regulations. Technicians operating the
DEXA equipment must be trained in the use of the equipment and in radiation safety.
Although the dosage of radiation a subject is exposed to for a whole-body scan is very
small, there is a potential for accumulated radiation exposure with repeated scans, and
there are some conditions (for example, pregnancy) that prohibit use. The devices do
have size limits for subjects due to the available scanning area. Subjects who are very
tall (over 6'4" [193 cm]) or who are severely obese may not be scanned accurately, as
their body may not fit within the limits of the available scanning area.
Advanced clinical imaging techniques have also been used to assess body
composition. Two such methods are computed tomography (CT) and magnetic
resonance imaging (MRI). Similar to DEXA, these methods are generally found only
in specialized clinical facilities or research laboratories and are not commonly used in
assessment of body composition outside research studies. These devices are able to
image tissues in the body in cross-sectional slices. The amount of tissue in each
section is estimated, and whole-body composition is estimated by summing the
sequential section images. These technologies have not been used on a sufficient
number or breadth of subjects to establish the SEE. The specialized nature of these
technologies makes their widespread use in body composition assessment unlikely in
the near future.
Once the appropriate body composition assessments have been completed and
the results are known, the subject will likely ask, “What do these numbers mean?”
The health, fitness, or nutrition professional may wonder, “What do I do with these
results?” The initial caution about body composition bears repeating here:
assessments of body composition are only estimates. Each method of assessment has
a degree of error that must be taken into account when analyzing and interpreting the
results, and this error may be compounded by technical, technician, or subject error.
Suggesting to athletes that body composition assessment is overly precise or using the
information to establish rigid goals is incorrect and inappropriate.
Weight is reported as a single number and is generally compared to previous
weights. A change in body weight can reflect a change in muscle mass, body fat,
hydration status, or a combination of these factors. Weight can fluctuate on a daily
basis and is most useful to athletes as a way to track hydration status, especially for
those who are training in hot, humid conditions and are losing large amounts of fluid
each day as sweat. In this instance, daily weight may be an appropriate means of
checking hydration status and ensuring adequate rehydration. Although athletes in
some sports must be focused on body weight because of weight restrictions or classes,
it is probably not appropriate for most athletes to be overly concerned about checking
their weight on a daily basis. For purposes other than hydration status or “making
weight,” a reasonable approach might be for an athlete to check weight on a less
frequent basis, such as once each week. Care should be taken to measure body weight
using the same scale if possible and under the same conditions, such as the same time
of day and the same timing in relation to exercise, food, and beverage consumption.
C. Body Composition and Weight Related to Performance
In many sports, there are certain physical characteristics that are associated
with success. For example, elite marathon runners tend to be lightweight, lightboned,
and have a relatively low percentage of body fat because these characteristics are
associated with moving the body a long distance as quickly and efficiently as
possible. However, within the ranks of elite marathon runners, there is a range of body
weights and there is not a certain percentage of body fat that is associated with
success. Based on the athlete's sport, genetic predisposition, and individual
characteristics, an athlete can set weight and body composition goals that are likely to
be associated with good performance and good health.
Body composition and other body anthropometric characteristics, such as
height, are physical characteristics that can have an impact on an athlete’s
performance, but these factors play a more important role in some sports, and for
different positions within certain sports, than others. For example, all bodybuilders
need to have a high percentage of skeletal muscle mass and a low percentage of body
fat to be competitive in this sport. Professional, long distance (road) cyclists have a
low percentage body fat. Conversely, body composition and weight play a minor role
in certain skill-oriented sports. Athletes that are successful in baseball or golf display
a wide variety of body types and body composition that may be more similar to the
general population (Figure 11.10). Professional baseball players may be fit and lean
like Derek Jeter or may have a body composition more similar to the average,
sedentary adult like C.C. Sabathia. Golf is another example in which athletes with
different body compositions, heights, and weights have been successful.
Many athletes today are physically taller and heavier than their counterparts of
the past. Mont- gomery (2006) compared the heights and weights of professional ice
hockey players in the 1920s to 1930s with those in the 1980s to 1990s. The latter were
4 inches (10 cm) taller and ~37 lb (17 kg) heavier. In contact sports, being physically
well matched to one’s opponent is important, although physical size alone is not the
determining factor in most sports. However, there is a physical uniformity, especially
in the position played in contact sports, that dictates the athlete be a certain size,
weight, or body composition.
The “optimal” body composition for an athlete must consider the mass,
strength, speed, and power demands of the sport, or the position within the sport. At
one extreme, the sumo wrestler represents an athlete that must possess a very large
body mass. This large body mass is difficult to push out of the competitive ring due to
inertia and lack of momentum. Strength and speed are important for these athletes, but
a very large body mass is critically important—a strong and fast sumo wrestler will
have little success if he is outweighed by several hundred pounds by his competitors.
The other extreme may be represented by a ski jumper. A certain amount of strength is
required for controlling the skis and for propelling the body into the air at the end of
the ski jump, but low body weight is a great advantage for these athletes to stay in the
air longer. Other athletes fall somewhere in between these extremes in terms of body
mass, body fat, and skeletal muscle.
Weight categories are necessary in certain sports, but the certification of
weight puts an emphasis on attaining a certain scale weight in order to compete. A
singular focus on scale weight can be problematic because weight can be manipulated
via changes in body water. Athletes can quickly change their weight by reducing
water intake and increasing water excretion through excessive sweating and the use of
diuretics (see Chapter 7). These are potentially dangerous practices because of the
negative effects they have on body temperature regulation. Boxing, wrestling, some of
the martial arts, and lightweight rowing are examples of sports that certify weight.
Physical appearance is a performance-related factor in some sports due to
subjective scoring and judging. In the sport of bodybuilding, the physical appearance
of the body is judged, although other elements are also considered, such as posing.
Figure skating, gymnastics, and diving include appearance as part of the scoring.
Ballet dancers and cheerleaders are judged on their appearance (See Spotlight
on...Athletes and Appearance—Meeting Body Composition Expectations). In many
cases, the cultural norm for males is to have a lean, muscular appearance, which can
be achieved through high-volume training. However, females may be expected to
have a thin but not overly muscular appearance, which may require chronic
undereating to attain and maintain a low body weight and a low percentage of body
fat.
Weight and body composition are useful information | for athletes as long as
this information is interpreted correctly. Daily weights can help the athlete determine
the amount of fluid lost during exercise and help assess hydration status. Monthly or
biweekly weights can also be used to track large changes in body composition. For
example, an athlete who wants to gain 20 lb (9 kg) of skeletal muscle mass or lose 20
Ib (9 kg) of body fat can track scale weight over many months. However, scale weight
can also be misinterpreted. Daily weights are not a good reflection of changes in lean
body mass or body fat. In some cases the athlete becomes too focused on the
“number” and not what the number represents. Scale weight is a broad measure of
change, but it cannot provide specific information about body composition.
D. Changing Body Composition to Enhance Performance
Many athletes want to change their body composition. Highly trained athletes
are typically lean but may want to gain muscle mass to increase strength or lose a
small amount of body fat to improve their power-to-weight ratio or their appearance.
Athletes hoping to advance to the next level, such as high school athletes to the
collegiate level and collegiate athletes to the professional level, may change weight or
body composition as a way to become more competitive. Lesser-trained athletes often
wish to increase muscle mass and lose body fat, sometimes in substantial amounts.
Some recreational athletes want to lose moderate to substantial amounts of body fat.
This loss of body fat may positively affect performance, but in many cases the desire
to lose body fat is related more to appearance and the desire for better health. A
minority of athletes need to gain body weight and need to increase body fat in
addition to increasing muscle mass. Regardless of the athlete's priorities, the same
questions are frequently asked: (1) How much should I weigh? (2) What percentage
of body fat should I have? (3) How do I increase muscle mass? (4) How do I lose or
gain body fat? and (5) How do I increase muscle mass and lose body fat at the same
time? This section explains how a target weight based on body composition is
determined, and briefly outlines the changes in exercise and training that are needed
to achieve muscle mass or body fat goals.
After body composition has been estimated as accurately as possible, athletes
can use that information to establish their “optimal” body composition goals. Athletes
should be cautioned to choose realistic lean body mass and body fat goals that
consider their genetic predisposition to leanness and fatness. Once body composition
goals are chosen, the weight that reflects those goals can be estimated. This weight is
referred to as a target body weight or body weight goal. The target body weight is
only an estimate, and rigid adherence to attaining a given scale weight or body
composition is never recommended.
When the appropriate stimulus is applied to skeletal muscle and the necessary
hormonal and nutritional environment is present, muscle mass can increase. First, an
overload stimulus must be applied consistently over time—the muscle must be
stimulated to produce force at a greater frequency, intensity, and/ or duration than is
accustomed. Athletes generally accomplish this through one of many strength-training
approaches. The increase in muscle mass is referred to as hypertrophy, and is a result
of individual muscle fibers being stimulated to increase in size by synthesizing more
contractile protein.
For the sedentary adult or the athlete who is not accustomed to strength
training, virtually any strength-training protocol will result in increases in strength and
some initial increase in muscle mass. Once athletes are accustomed to basic strength
training, further increases in muscle mass can be achieved through periodized strength
training. The hypertrophy phase of periodized strength training is designed to
maximize the potential for increasing muscle mass and is characterized by an
emphasis on increasing the total volume of strength training. Increasing
strengthtraining volume is accomplished by structuring a large number of sets and
repetitions of a variety of strengthtraining exercises. The intensity or load (amount of
weight lifted) is kept in the moderate range so that the prescribed number of sets and
repetitions can be completed.
The amount of increase in muscle mass in response to strength training is
difficult to accurately predict and is dependent upon a number of factors such as
genetics, body type, hormonal status, and nutritional status. Those individuals with
ectomorphic body types may not have the genetic disposition to add large amounts of
muscle mass compared to those with more mesomorphic body types. Testosterone and
growth hormone are the primary hormones responsible for stimulating an anabolic, or
tissue-building, state in the body, particularly for muscle and connective tissue. There
are large interindividual differences in circulating testosterone concentrations,
certainly between males and females, but even among males.
Proper nutrition is necessary to support the increase in muscle size that is
associated with the resistance-training programs described above. Although many
nutrients are important for muscle growth, two areas receive the majority of attention
—energy (kcal) and protein. Synthesis of muscle tissue requires positive energy
balance (that is, caloric intake is greater than caloric expenditure). The athlete must
also be in positive nitrogen balance and positive muscle protein balance. Positive
nitrogen balance occurs when total nitrogen (protein) intake is greater than nitrogen
lost via the urine and feces. In other words, the athlete must be consuming a sufficient
amount of dietary protein. Positive muscle protein balance occurs when muscle
protein synthesis is greater than muscle protein breakdown. To achieve positive
energy, nitrogen, and muscle protein balance, an adequate energy intake is just as
important as an adequate protein intake.
The general principles for the loss of body fat are the same for athletes and
nonathletes: an increase in energy expenditure (activity or exercise), a decrease in
food (energy) consumption, or a combination of both. There are thousands of weight-
loss diets, but the common denominator is a decrease in caloric intake that results in
fat loss over time. For the obese, sedentary individual, the restriction of total energy
intake and the length of the energy restriction seem to be more important than the
carbohydrate, protein, and fat content (that is, macronutrient composition) of the diet.
Higher-protein, low-energy diets may be beneficial for athletes because they may help
to protect against the loss of lean body mass, but carbohydrate intake must be
sufficient to support the resynthesis of muscle glycogen depleted by training.
Many athletes want to simultaneously increase muscle mass and decrease
body fat. In other words, they want to remain the same weight but they want to
“replace” 5-10 lb (~2.2-4.5 kg) of fat with 5-10 lb of muscle. Although this sounds as
if it would be easy for the body to accomplish, anabolism (synthesis) and catabolism
(breakdown) are biologically opposite processes and it is difficult to estimate an
appropriate daily caloric intake to achieve both simultaneously. A prudent
recommendation is to focus on one goal at a time. For many athletes, there is a greater
benefit to increasing muscle mass than to decreasing body fat. Weight may eventually
be the same, but it will probably fluctuate as muscle mass is increased and then body
fat is decreased.
The magnitude of the desired fat loss or lean body mass gain is a factor in
deciding the best time in the training cycle to make body composition changes. Small
losses of body fat and weight may be a consequence of the athlete’s return to
preseason training from the relatively sedentary off-season period. If the athlete
continues to consume approximately the same amount of energy (kcal), then the
increase in energy expenditure from a return to training will result in a loss of body
fat. Similarly, an athlete who experiences a small loss of muscle mass in the off-
season will see a gain in lean body mass with a properly designed preseason
resistance exercise and nutrition program. Athletes can maintain a relatively stable
body composition and weight by adjusting their energy intake to meet the energy
expenditure requirements of each training cycle.
The off-season is characterized by a reduction in exercise compared to the
competitive season. It is also time away from the rigors of training. Some athletes
may wish for time away from the rigors of following a diet that supports training,
such as high daily carbohydrate consumption, timing of food intake, and monitoring
of energy intake. The offseason can be an important break from disciplined eating,
although it is not a time for reckless abandon of all dietary restraint. However, the loss
of a large amount of body fat takes time, and some of that time will likely be during
the off-season when a moderate restriction of energy intake is feasible and will not
interfere with training. The suggestion to lose some weight in the off-season may
come as a surprise to many athletes and may be difficult for some who prefer to have
few dietary restrictions during the offseason. Some of these athletes believe that large
and rapid fat loss will be possible early in the preseason when they return to training.
Many are disappointed that preseason losses are not larger and that fat is not lost as
rapidly as they had hoped, and some engage in “crash diets” that produce large and
rapid weight loss but are detrimental to training, hydration status, and health.
Some sports have designated weight categories because differences in body
size make it impossible for all athletes to fairly compete among one another.
Examples include wrestling, boxing, martial arts, and lightweight rowing. In sports in
which weight must be moved, such as distance running, gymnastics, high jumping, or
ski jumping, participants with a low body weight (but sufficient muscularity)
generally have a performance advantage over those with a higher body weight due to
larger amounts of body fat. Women’s gymnastics, rhythmic gymnastics, and figure
skating have a subjectively scored element, and a low body weight may influence
artistry scores. Cheerleading and ballet dancing, which require athleticism, are not
scored, but being chosen for participation may depend on body composition.
Some athletes are underweight and want to increase both muscle mass and
body fat. This population has not been well studied. It is generally recommended that
energy intake be increased by 500 kcal daily (Rankin, 2002). The additional energy
should come from nutritious foods such as fiber-containing carbohydrates, proteins,
and heart-healthy fats. Fat is the most energydense nutrient; however, simply adding
large amounts of additional fats to the diet may be counterproductive. In some
underweight people, a high-fat meal or snack is so satiating that food is not consumed
again for many hours and results in a net decrease in the total energy (kcal) intake for
the day.
E. Supplements Used to Change Body Composition
Changing body composition through diet and exercise demands daily attention
and discipline, and is typically a slow process. Therefore, it is not surprising that
athletes look to supplementation of substances that promise to build muscle and
reduce body fat easily and quickly. Some of these supplements may contain
substances that are banned by sports-governing bodies. Before taking any supplement
athletes should ask five critical questions: (1)-Is it legal? (2) Is it ethical? (3) Is it
pure? (4) Is it safe? and (5) Is it effective?
Perhaps no group of supplements holds more promise in the eyes of athletes
than those involved in muscle protein synthesis. Increased muscle size and strength
are important performance factors in many sports. As discussed previously, the
building of muscle tissue through training and diet is a slow process that requires hard
work and discipline. Substances that have received tremendous attention include
testosterone and testosterone precursors. Testosterone is a hormone that influences
muscle protein synthesis. The use of anabolic steroids, scheduled drugs that are nearly
identical to testosterone, is known to increase muscle mass and, in some individuals,
muscle strength (American College of Sports Medicine, 1984). The self-prescribed
use of anabolic steroids is illegal, prohibited by sports governing bodies for ethical
and safety reasons, and associated with some substantial medical risks, especially for
females because of their irreversibility.
Because athletes can be permanently banned from their sport for testing
positive for anabolic steroids, many look for dietary supplements that would provide
similar benefits. Among the most popular are the prohormones, compounds that are
precursors to testosterone. Many prohormones, such as androstenedione, are regulated
under the Anabolic Steroid Control Act of 2004 and are banned by sportsgoverning
bodies. Androstenedione, androstenediol, and, to a lesser extent, DHEA are often
referred to as prohormones. They are precursors to testosterone and have similar, but
not exact, chemical structures. Athletes hope that these prohormones will elevate
testosterone concentration and consequently increase muscle protein synthesis.
Studies of all of these compounds have yet to confirm this hope. Although some
studies showed a short-term rise in testosterone concentration with supplementation,
this short-term rise has no effect on muscle size, strength, or power (Broeder et al.,
2000; Tipton and Ferrando, 2008). In fact, androstenedione supplementation
preferentially increases estradiol (via estrone), not testosterone, which can result in
the development of breast tissue in males.
Most people find it difficult to lose body fat and to maintain the loss. Any
dietary supplement that may increase the amount lost or accelerate the rate of weight
loss will be popular. Because dietary supplement manufacturers do not have to prove
either safety or efficacy before a supplement is sold, there is an endless stream of
weightloss supplements on the market. Perhaps the most controversial weight-loss
supplements are those that contain ephedrine (for example, ephedra), which may be
used alone but is usually found in combination with caffeine.
The safety of ephedrine-containing dietary supplements has always been
controversial, and reviewing its history helps to underscore some important issues
about safety, purity, and supplement regulation in the United States. After the passage
of the Dietary Supplement Health and Education Act in 1994, the sale of dietary
supplements containing ephedrine began to increase. The FDA expressed concern, in
part, because of the number of adverse event reports (AERs) they received.
Consumers can report adverse events to a hotline, and by 1997 half of the AERs
received involved ephedrine. The adverse events reported included known side effects
such as headache, increased heart rate, increased blood pressure, and insomnia. The
AERs also included deaths to otherwise healthy middle-aged and young adults.
Citrus aurantium, also known as bitter orange, contains synephrine and
octopamine, which are chemically similar to epinephrine and norepinephrine,
respectively. Supplements containing bitter orange have become more popular as
ephedrine-containing supplements have been removed from the U.S. market. Bitter
orange is marketed as a weight-loss aid that enhances fat metabolism. Although citrus
aurantium and similar stimulants can slightly increase resting metabolic rate, the
temporary and small increase in RMR is unlikely to result in clinically significant
weight loss. There is some promise for bitter orange’s effect on enhancing fat
metabolism, but there are many questions about safety and efficacy (Greenway et al.,
2006; Haaz et al., 2006). Under both resting and exercise conditions, bitter orange and
similar compounds increase blood pressure and plasma glucose. Some minor adverse
events, such as a temporary elevation in heart rate, and serious adverse events such as
stroke, have been reported.
A small number of studies have been conducted on the use of nonherbal
ephedrine and caffeine preparations in healthy males as a performance enhancer.
Research in this area has been limited due to the ethical issues related to administering
potentially harmful substances to human subjects. Ephedrine and caffeine
administered together has been reported to increase performance by delaying time to
exhaustion by up to 30 percent (Schekelle et al., 2003). Athletes also report a decrease
in perceived exertion (Magkos and Kavouras, 2004). These results are not surprising
given the stimulatory properties of these substances, Studies have not shown that
ephedrine and caffeine, alone or in combination, are effective in increasing muscle
strength, muscle size, or anaerobic capacity.
Conjugated linoleic acid (CLA) is an isomer of linoleic acid, an essential fatty
acid found in lamb, beef, and dairy products. The major naturally occurring isomer is
cis-9, trans-11, but most supplements have a mixture of the natural isomer and a trans-
10, cis-12 isomer. In animal studies, it is the trans-10, cis-12 isomer that can reduce
the deposition of fat in adipose tissue; however, this isomer is also associated with
deposition of fat in the liver and spleen and insulin resistance in the test animals
(Wang and Jones, 2004). In humans, trans-10, cis-12 isomer is likely to be
incorporated into adipose tissue whereas the cis-9, trans-11 isomer tends to be
incorporated into skeletal muscle cells.
F. Disordered Eating and Eating Disorders
The prevention, detection, and management of disordered eating and eating
disorders are of critical importance to athletes and those who work with them.
Disordered eating and eating disorders are deviations from normal eating and are
often characterized by obsession or inflexibility. Eating disorders such as anorexia
nervosa and bulimia nervosa are psychiatric diseases and, in some cases, are fatal.
Although athletes in sports that emphasize low weight and a thin appearance are at a
greater risk, any athlete in any sport of either gender may suffer from disordered
eating or an eating disorder.
The following case study shows how an athlete can move from a normal
eating pattern to disordered eating and then to an eating disorder. Notice the many
factors that influence this progression, including inappropriate eating and dieting
behaviors as well as training demands and psychological stresses. This case study will
be used throughout this chapter to illustrate the development of and some of the
problems associated with disordered eating and exercise patterns in athletes.
By her junior year she was featured in her hometown newspaper as someone
to watch. She adopted a semivegetarian diet and altered her running stride to make it
more efficient. She came in second in the regional meet and earned the right to go to
the state championships. There she had a strong start but faltered down the stretch,
and she was disappointed for herself and her family. Her coach told her that if she
trained just a little harder that she could be a contender in her senior year. Her parents
were excited about the prospects of her earning a college athletic scholarship; without
some financial help they had little hope of sending Karen away to college.
Her freshman year of college was an eye-opener. Her college coach was much
more demanding than her high school coach and everything about her seemed to be
under scrutiny. She had made only a few friends, acquaintances really, and she missed
her family, although her coach was like having family close. Much of the dorm food
was not vegetarian, and she found herself with few choices and even fewer foods that
she enjoyed eating. One of her goals was to have the highest GPA on the team, but
attaining perfect grades in college was much harder than in high school. When she
was not training, she was studying. Karen was surprised to find out that the athletic
scholarship she thought was guaranteed had to be renewed each year based upon her
running and academic performances, something that really upset her parents.
Although her coach never said it directly, he intimated that she would perform better
if she were leaner. A couple of her teammates, whom she noticed were thin, wondered
aloud if she had what it took to make it as a college runner at an NCAA Division I
school. That was all the motivation that she needed to develop a stricter training
program, and, for the first time in her life, a diet to lose weight and become thinner.
By the beginning of thé season she had received clearance to restart her
training, but her injury had substantially set her training back and she was concerned
that she was entering racing season without the necessary preseason training. Karen
now relished her training runs and began to run on designated rest days, although she
knew that if her coach was aware of this he would never have allowed it. If she had
been honest with herself, she would have realized that she did not so much love
running anymore, rather, she needed running. Her coach had mentioned that he was
worried about her apparent lack of eating, and she took his comment as a good sign
since he obviously was paying attention to her again. Karen assured him that she was
eating more now that she was training. She made sure that she was not lying by
increasing the size of her salads. Secretly, she was a bit worried because her menstrual
periods, which had been light but regular since high school, were now almost
nonexistent—just two periods in the last year. She had not dated anyone since coming
to college so she was not worried about being pregnant. But she did have an
immediate health concern—recurrent upper respiratory tract infections that had
plagued her for months.
Her junior season started with an excellent showing at a big meet, and her
coach repeated his prediction that this would be her breakout year. Her next effort was
hampered by a cold, and her coach seemed sympathetic to her frequent infections,
although he did ask her specifically about her training and diet. Two more meets
featured mediocre performances and she was not chosen to travel to an out-of-state
invitationonly event. She resolved to work harder, training more than usual and eating
a little less than she had been for the past few months. At the next meet she fainted at
the start line and her coach said they needed to talk. She believed that she just had a
bad day and that everything would be fine for the next meet; he believed that she had
anorexia athletica and needed immediate treatment.
G. Eating and Exercise Patterns
Disordered eating, eating disorders, and excessive exercise are deviations from
normal; therefore, normal patterns must be known before disordered ones can be
determined. In the case of eating, “normal” is not easy to define but it generally
describes an eating pattern that is flexible and not obsessive. Normal exercise patterns
vary according to the sport and level of training; however, a normal amount of
exercise is an exercise intensity and duration that supports training and performance
and is not associated with overtraining.
For individuals with access to an adequate amount of food, normal eating
represents the middle area on the eating continuum shown in Figure 12.1. When
considered over a period of time, such as a week, month, or year, food may be either
under- or overconsumed, and on any given day the energy (kcal) or nutrient content
may be higher or lower than recommended guidelines. Normal eating consists of
consuming foods that are nutrient rich as well as eating some foods that might have a
low nutrient content. The diet is moderate, balanced, and varied, and is flexible,
especially in response to social situations. Normal eating involves moderate
constraint, not reckless abandon or overly strict discipline.
Normal eating in athletes is particularly hard to define because some athletes
must follow fairly strict eating guidelines to support their training and performance
goals. A distance runner must be concerned about excessive caloric intake because
weight gain as body fat could negatively affect training and performance. Rigorous
training, especially during the latter part of the preseason, and the demands of
competition require a well-thought-out diet plan. For example, a distance runner must
be diligent about consuming the proper amount of carbohydrates daily or risk not
restoring the muscle glycogen used during training and competition. The moderate
restraint and dietary flexibility that is part of normal eating necessarily becomes a bit
more restrained and less flexible during periods of intense training and competition,
but it should not become overly restricted or inflexible. Normal eating among highly
trained athletes is characterized by discipline, not by obsession.
Disordered eating (DE) represents a deviation from normal eating, but the
individual does not meet the diagnostic criteria for an eating disorder (ED)— anorexia
nervosa, bulimia nervosa, or eating disorders not otherwise specified. Disordered
eating is not well defined or easily recognized and encompasses a large area on the
eating continuum (Figure 12.1). The deviation from normal may be occasional and
minor or it may progress and become more frequent and pathological. The difficulty
lies in identifying the overall context of normal eating and then determining the
degree to which behaviors deviate from normal, tracking the progression, and
identifying the level of severity. Individuals may be described as having a subclinical
eating disorder if they demonstrate a number of disordered eating behaviors (see
examples in the next column) and exhibit associated psychological issues (Beals, in
press). Single disordered eating behaviors are not as severe as a subclinical eating
disorder, which is not as severe as a clinical eating disorder, but any of the three
conditions is cause for concern and intervention.
Eating disorders represent a substantial deviation from normal eating (Figure
12.1) and are psychiatric conditions that involve body image issues. The three clinical
eating disorders recognized by the American Psychiatric Association (APA) are
anorexia nervosa, bulimia nervosa, and eating disorders not otherwise specified
(EDNOS), and each has established criteria listed in the Diagnostic and Statistical
Manual of Mental Disorders, 4th edition (DSM-IV; APA, 1994). Anorexia nervosa
and bulimia nervosa share most clinical features, although body weight is a major
feature that differs between these two conditions. Interestingly, it is not uncommon for
individuals to “cross over” between anorexia and bulimia (Reiter and Graves, 2010).
Those with EDNOS do not meet the specific criteria established for either anorexia or
bulimia, but a variety of significant problems are present, as will be illustrated later in
this chapter. Although this chapter focuses on eating and exercise behaviors, one
should not forget that eating disorders are psychiatric diseases, and their development
is a result of psychological disturbances often related to issues of control.
The prevalence of anorexia nervosa in lateadolescent and early-adult females
is estimated to be 0.5-1.0 percent of that population. It is most prevalent in females
(more than 90 percent of all cases). Males do manifest anorexia nervosa, although the
prevalence _ is unknown. The typical age range for females exhibiting anorexia
nervosa is early adolescence (~age 13) through early adulthood (mid-20s), and critical
ages appear to be age 14 (often the start of high school) and age 18 (start of college,
living away from family). The incidence appears to be on the increase, but this trend
is hard to document.
Restricting type: during the current episode of Anorexia Nervosa, the person
has not regularly engaged in binge-eating or purging behavior (i.e., selfinduced
vomiting or the misuse of laxatives, diuretics, or enemas). Binge-eating/Purging type:
during the current episode of Anorexia Nervosa, the person has regularly engaged in
binge-eating or purging behavior (i.e., selfinduced vomiting or the misuse of
laxatives, diuretics, or enemas).
Bulimia nervosa is characterized by recurring binge eating coupled with
inappropriate ways of preventing weight gain following the eating binge. Two
subtypes exist. The first, known as the purging type, includes self-induced vomiting or
the use of laxatives, diuretics, or enemas. The second, nonpurging type, involves
fasting or excessive exercise. Those who purge attempt to keep the food from being
absorbed (self-induced vomiting, use of laxatives) or prevent scale weight from
increasing (use of diuretics or enemas). The nonpurgers compensate for the increased
caloric intake by subsequent fasting or excessive exercise. Those with bulimia may
use a number of methods, but purging by self-induced vomiting is the most common.
There can also be a fine line between the frequency, intensity, and duration of
exercise that improves performance and that which results in a decline in
performance. The latter is known as overtraining and demonstrates the difficulty of
identifying the appropriate amount of exercise and recovery to achieve optimal fitness
and reach a peak level of performance. As discussed earlier in this chapter in relation
to eating behaviors, there are subtle differences in the intent of the exercising behavior
and the athlete’s psychological state. These differences help to distinguish committed
exercise training from overtraining from exercise dependence.
H. Disordered Eating and Eating Disorders in Athletes
In some respects, athletes with disordered eating and eating disorders are
similar to nonathletes, thus a basic understanding of eating disorders and how they
develop is necessary. However, there are some important differences between athletes
and nonathletes because athletes are always accountable for their performance.
Disciplined eating and high-volume exercise are often expected of athletes, and it can
be difficult to distinguish when disciplined has become obsessive and high volume
has become excessive.
The prevalence of disordered eating and eating disorders in athletes is very
difficult to determine. Beals (in press) notes that only a few studies have used a large
enough sample size and valid survey instruments to be considered scientifically
sound. Published figures range from 1 to 62 percent in female athletes with similar
estimates for male athletes (0-57 percent). Such wide ranges have limited usefulness
but suggest that disordered eating and eating disorders have a high prevalence in some
sports.
Karen was a naturally talented runner who had a “normal” eating pattern when
she entered high school. As she became more dedicated to improving her running, she
adopted a semivegetarian diet in her junior year of high school to support her training
and performance goals. If she consumed sufficient kilocalories and nutrients and
maintained some dietary flexibility, then her diet would be considered “normal” for a
welltrained athlete. She enjoyed the recognition she got from her parents for being in
the newspaper. In her senior year she followed a more strict vegetarian diet, preparing
her own food and eating alone. She started to become socially isolated at mealtime,
and her diet was becoming more inflexible. During therapy, Karen identified her
senior year as the point in time when she began to move away from “normal” on the
eating continuum (Figure 12.3) because she had found a way to “control” her parent’s
comments and her feelings of low self-esteem that accompanied dinnertime
conversation. At the same time her successful cross country season was showering her
with attention, something she realized later that she desperately needed.
When her injury was resolved, she continued to consume a restricted diet and
voluntarily engaged in excessive exercise. Increasing the serving size of a low-calorie
food such as salad was not an appropriate dietary response to a substantial increase in
training volume. When she did not get an invitation to an important meet, her
response was to train more and eat less. At this point, Karen exhibited all the signs of
anorexia athletica and had unresolved psychological issues related to control, self-
esteem, and personal relationships.
Excellent athletic performance, especially at the elite level, requires rigorous
training. A nutritious diet supports training and can improve performance, and some
athletes must follow fairly strict eating protocols to support their training, body
composition, and performance goals. Both training and eating can become
regimented, a factor that may contribute to disordered eating. A fine line separates
rigorous training and eating regimes that enhance performance and support health
from disordered eating and exercise dependence that hurt performance and undermine
health. Crossing this imaginary line may be accidental or intentional. Because early
intervention is critical for treatment and recovery and the athlete may be unaware or
in denial that problems exist, it is important for coaches, athletic and personal trainers,
and others who work closely with athletes to be able to distinguish that which is
“normal.”
As might be expected, the extent of the disordered eating behaviors is
associated with the effects on performance and health. More severely dysfunctional
behaviors used for a longer period of time typically have more a more negative effect
on health and performance. For some athletes with mildly abnormal eating and
exercise behaviors, performance may not be affected to a large degree. However,
eating and exercise obsessions likely have an effect on mental health and, over time,
an effect on physical health including anemia, frequent infections, and increased risk
for injury. Some athletes with severe and prolonged eating disorders have died, often
at a young age.
Early intervention is critical in the treatment of disordered eating and eating
disorders. If left alone, athletes typically do not resolve these issues themselves. In
some cases, the athletes do not realize that they have fallen into a disordered eating
pattern; in other cases, the athletes staunchly deny that an eating problem exists. If a
coach, athletic trainer, teammate, or any other individual associated with the athlete
suspects that any degree of disordered eating exists, the question is not when, but how
to intervene.
Disordered eating and eating disorders do not develop in a vacuum. The IOC
Medical Commission (IOC, 2005) notes that several factors may influence their
development. Western cultures emphasize thinness, and females frequently restrict
food intake to lose weight. Females who equate thinness with success are more
susceptible to developing eating disorders. From the female athlete’s perspective,
“success” may include being thinner than a teammate or receiving more attention
from her coach because of her thin body. Female athletes in sports in which thinness
is desirable can face extraordinary pressures, especially as they try to reach the elite
levels of their sports. Decreasing body weight or reducing body fat can, and often
does, lead to improved performance initially and a desirable appearance in revealing
clothing. However, not only is the belief that an ever-lower body weight or body fat
percentage is beneficial incorrect (it leads to poorer performance), but this belief is a
powerful risk factor for the development of an eating disorder.
I. Female Athlete Triad
The Female Athlete Triad (Figure 12.4) is a term used to describe three
interrelated factors—energy availability, menstrual function, and bone mineral density
—each of which develops along a continuum. Each factor may progress to a point
where it is a clinical condition. For example, energy availability may be low due to
disordered eating or an eating disorder and amenorrhea or osteoporosis may exist. The
three may be present together and have developed in sequence—low energy
availability due to low energy (caloric) intake and high energy expenditure leads to
amenorrhea that leads to osteoporosis—although each of these conditions can occur
independently of the others.
Energy availability is defined as dietary energy intake minus exercise energy
expenditure. Essentially, it is the amount of energy available to the body for other
biological functions. Low energy availability results when the female athlete is in
negative energy balance. Negative energy balance, also known as an energy deficit, is
the result of energy expenditure from exercise exceeding energy intake from food.
This deficit may last months or years. In adolescent athletes, physical growth also
requires energy, and growth may contribute further to the energy deficit.
Amenotrhea is defined as the absence or suppression of menstruation. In the
United States, primary amenorrhea describes a female who has gone through puberty
but by age 15 has not yet menstruated. In secondary amenorrhea, the female began
menstruating but menstruation has been absent for 3 or more months. There are a
variety of medical conditions that may have an effect on normal menstruation
patterns. In the context of the Female Athlete Triad, the amenorrhea is a result of low
energy availability and is not due to some other edical condition or contraceptive
technique that may result in absent menstruation. This type of amenorrhea is known
as functional hypothalamic amenorrhea.
In the past, amenorrhea in athletes was attributed to low body fat stores and
the stress of exercise. These factors are no longer believed to play causative roles.
Rather, the amenorrhea seems to be due to an energy deficit that alters the secretion of
luteinizing hormone (LH). Menstruation is regulated by a number of hormones,
including follicle-stimulating hormone (FSH), luteinizing hormone (LH), and
estrogen. Figure 12.5 illustrates the expected hormonal fluctuations associated with
menstruation, although many variations are seen. During the first few days of the
menstrual cycle the growth of one egg is accelerated. One to 2 days prior to ovulation,
there is a surge in LH secretion so that ovulation can occur. The unfertilized egg
grows and secretes estrogen and progesterone, hormones that inhibit the secretion of
LH and FSH (Guyton and Hall, 2010). The current prevailing theory is that low
energy availability disrupts the normal secretion of luteinizing hormone, resulting in
amenorrhea. The disruption can occur within 5 days when energy availability is
reduced substantially.
Achieving peak bone mineral density and preventing or slowing the loss of
bone mineral with age are important factors in lifelong bone health (see Chapter 9 for
a detailed discussion). Both low energy availability and amenorrhea affect the bone
mineral status of female athletes. Low energy availability results in chronic
undernutrition, depriving the body of the nutrients needed for proper bone
development and maintenance. Among the nutrients that may be deficient are those
closely associated with bone health—protein, calcium, and vitamin D. Amenorrhea is
associated with estrogen deficiency. One of the actions of estrogen is protection
against calcium loss from bone, and a low estrogen concentration results in loss of
bone calcium and alterations in bone microarchitecture. Of the two factors, low
energy availability is particularly powerful because of its far-reaching effects on bone-
formation, including nutrients as well as a variety of hormones.
Cobb and colleagues (2003) studied 91 welltrained female distance runners
ages 18 to 26 years. Thirty-three athletes had zero to nine menstrual periods in a year
whereas the remaining subjects (58 athletes) had normal menstruation. Bone mineral
density was determined by DEXA for the entire body as well as the hip and spine.
When BMD was compared to those with eumenorrhea (that is, normal menstruation),
the amenotrheic athletes had 3 percent less in the entire body, 6 percent less in the hip,
and 5 percent less in the spine. Based on spine measurements, two of the amenorrheic
runners were classified as osteoporotic and nearly half were osteopenic. In
comparison, none of the eumenorrheic athletes were osteoporotic and only 26 percent
were osteopenic.
The prevalence of the Female Athlete Triad, especially the manifestation of
clinical conditions of all three factors, is hard to determine. The prevalence of low
energy availability without disordered eating or eating disorders is not known and has
not been well studied. The prevalence of disordered eating in female athletes has an
estimated range of 1-62 percent, with a greater prevalence in sports that emphasize a
lean or thin build. The prevalence of secondary amenorrhea also varies widely based
on the sport, with a high prevalence reported in ballet dancers (69 percent) and
distance runners (65 percent). Similarly, the prevalence of osteopenia (22-50 percent)
and osteoporosis (0-13 percent) in young female athletes is cause for concern.
J. The Lifelong Athlete
“Everyone is an athlete. The only difference is that some of us are in training,
and some are not.” George Sheehan, physician, writer, and running philosopher,
eloquently expressed the notion that the human body is made to be active and that
people have different reasons and motivations for being physically active, exercising,
or participating in sport (Sheehan, 1980). The majority of this textbook has
approached sports nutrition from the perspective of highly trained athletes who are
trying to achieve maximum performance and success in their sports. However,
athletes with this single-minded goal not only make up a very small percentage of the
population, they usually pursue their performance goals for a short amount of time
relative to their life span. Few athletes remain highly competitive in their sports over a
large portion of their lifetime.
The term athlete often brings to mind the highly trained collegiate or
professional player. However, individuals participate in sports competitively or
recreationally long after their best performing years, and ideally people engage in
exercise or remain physically active throughout their lives. An obvious factor that
changes over an athlete’s life is the level of performance, but lifestyle, personal and
professional obligations, and health also change. All these factors must be considered
when working with lifelong athletes.
Most collegiate athletes do not become professional athletes. For example, the
National Collegiate Athletic Association (NCAA) estimates that less than 2 percent of
NCAA football players, 1.2 percent of male basketball players, and 8.9 percent of
baseball players will play professionally (http://www.ncaa.org/). Some postcollegiate
athletes find that they wish to continue to train, albeit at a lower level, and eventually
may become masters athletes. Others find that exercise becomes a lower priority and
they are essentially “former” athletes. In either case, the reduction in training
necessitates adjustments to the diet, particularly caloric intake. Weight gain is
associated with chronic disease risk even in former elite athletes.
Pihl and Jurimae (2001) surveyed 150 former elite male athletes to study the
relationship between changes in body weight and heart disease risk. Weight gain
greater than 22 lb (10 kg) was associated with an increase in percentage of body fat
and abdominal fat. These men were at a greater risk for elevated blood pressure, low-
density lipoprotein cholesterol (LDL-C), and triglycerides. One of the biggest
challenges for former competitive athletes, especially those in high-energy-output
sports, is to prevent weight (fat) gain and the diseases associated with excessive body
fat after they stop training and competing.
The Dietary Guidelines for Americans are published every 5 years, most
recently in 2010 (see Chapter 1). These diet and exercise recommendations promote
health and reduce the risk for chronic diseases to Americans over the age of two. The
2010 Dietary Guidelines (U.S. Department of Health and Human Services and U.S.
Department of Agriculture, 2010) emphasize changing one’s lifestyle, including a
total diet that is energy balanced and nutrient dense. The typical American diet is too
low in vegetables, fruits, high-fiber whole grains, lower-fat milk and milk products,
and seafood. There is an overconsumption of solid fats and added sugars (SoFAS),
refined grains, and sodium. Regardless of the level of energy expenditure daily, the
Dietary Guidelines can be used as a basic pattern.
K. The Impact of Overweight and Obesity on Chronic Diseases
Chronic disease is defined as a disease lasting 3 months or more that can be
treated but not cured. Some examples of chronic diseases include cardiovascular
disease, most cancers, diabetes, and osteoporosis. Obesity is also considered a chronic
disease by most health-related organizations because the number of formerly obese
individuals who maintain their weight loss over their lifetimes is low. Of the 2.4
million people in the United States who die each year, approximately 70 percent die
from chronic diseases (National Center for Health Statistics, 2010). Figure 13.2
compares the leading causes of death with the actual causes of death using data from
the year 2000. Although heart disease and cancer are the leading causes of death in the
United States, tobacco use, poor diet, and lack of exercise are the major contributing
factors (Minifo et al., 2002; Mokdad et al., 2004). As tobacco usage and secondhand
smoke exposure decline, poor diet and lack of exercise are expected to become the
leading modifiable causes of death. In the case of cancer, poor diet and obesity
contribute to approximately 30 percent of all cancer deaths, similar to the number of
cancer deaths caused by tobacco use.
According to the Centers for Disease Control and Prevention (CDC),
American society has become “obesogenic,” a term used to describe environments
that promote increased food intake, the consumption of unhealthy foods, and physical
inactivity. The fundamental causes of overweight and obesity include genetics,
behavior, and the environment and their interactions.
Women often wonder if pregnancy promotes obesity. For the majority of
women, pregnancy is not associated with an increased risk for developing obesity.
One and one-half years after delivery, the average woman will be only 1.1 pound
(~0.5 kg) more than her prepregnancy weight. However, 15-20 percent of women will
gain a substantial amount of weight as body fat and are at risk for obesity.
Under normal circumstances, the body regulates weight as it does many other
physiological factors, with a variety of homeostatic mechanisms that respond to short-
term changes to maintain long-term balance. Body weight is maintained by balancing
the energy equation—matching food (energy) intake to energy expenditure over long
periods of time. Although the energy balance equation is a simple concept (see
Chapter 2), the mechanisms that govern the body’s intake of food and expenditure of
energy are complex, interrelated, and not entirely understood. The dramatic increase
in the incidence of obesity in adults and children also indicates that these mechanisms
may be altered or disrupted, resulting in long-term and persistent changes in body
weight regulation.
One signal that stimulates appetite and initiates food intake is ghrelin, a
hormone synthesized by cells in the stomach. Secretion of ghrelin increases before
meals and makes pecple feel like eating. Eating causes ghrelin levels to decrease.
Ghrelin acts on receptors in the hypothalamus, causing an increase in the secretion of
Neuropeptide Y (NPY). Through neural signaling pathways that are not completely
understood, NPY acts to increase the release of other neuropeptides by the
hypothalamus that are strong stimulators of appetite and hunger, leading to food
intake.
In 2009, the American Dietetic Association released an updated position paper
on weight management. A fundamental principle is that both the prevention and
treatment of overweight and obesity requires a lifelong commitment to a lifestyle that
includes healthy foods and activity. An individualized reduced-calorie diet is the basic
dietary component of a comprehensive weight-management program. Reducing
dietary fat and/or carbohydrates is a practical way to create a caloric deficit of 500 to
1,000 kcal below estimated energy needs and should result in a weight loss of 1-2 lb
per week.
The Weight Watchers program has evolved since its inception in 1966 and
currently involves a point system known as PointsPlus®. All foods are assigned
points based on fat, protein, carbohydrate, and fiber contents. Daily and weekly point
targets are assigned. Points can also be earned by exercising, and these points can be
used to add more food to the diet plan or to accelerate the rate of weight loss. The
Weight Watchers diet reduces caloric intake indirectly through the point system, rather
than by a direct counting of calories. The diet is low in fat and high in fiber. The
hallmark of the Weight Watchers program has been its support system, either in
person or online. The program also focuses on teaching participants sensible eating
habits.
L. Diet, Exercise, and Chronic Disease
Diet and exercise play important roles in preventing and treating overweight
and obesity, which are conditions that directly affect many other chronic diseases.
Diet and exercise also play non-weight-related roles in many chronic diseases.
Hypertension is known as a silent killer because of the lack of recognizable
symptoms. In most cases the cause is unknown. Genetic predisposition is very
powerful, but there are a number of nutrition- and exercise-related factors that affect
blood pressure. Excessive energy intake over time is a major factor because it leads to
obesity. Obesity negatively affects a number of the body’s systems that regulate blood
pressure. Blood pressure may also be affected by dietary sodium intake. In general, as
sodium intake increases blood pressure increases, although not all people with a high
sodium intake will be hypertensive. Some individuals are sodium sensitive, and a high
dietary sodium intake has a direct effect on raising their blood pressure. In these
individuals, a reduction in sodium intake results in a decrease in elevated blood
pressure. Research has shown that higher intakes of potassium, such as consuming a
variety of fruits and vegetables daily, polyunsaturated fatty acids, and protein may
help to reduce blood pressure.
Diabetes is a metabolic disease characterized by a high blood glucose
concentration and is typically divided into two types. Type 1 diabetes, also referred to
as insulin dependent diabetes mellitus (IDDM), is an autoimmune disease that
destroys the beta cells of the pancreas, which results in an inability to manufacture
insulin. Type 1 diabetes makes up less than 10 percent of all the cases of diabetes in
the United States. Far more prevalent is type 2 diabetes, also known as non-insulin
dependent diabetes mellitus (NIDDM), which accounts for more than 90 percent of all
U.S. diabetes cases and affects at least 21 million people. In some cases, individuals
produce too little insulin, but in most people with type 2 diabetes the insulin produced
is ineffective because cells, particularly muscle, fat, and liver cells, are insensitive to
its action. This condition is known as insulin resistance. Approximately 85 percent of
people with type 2 diabetes are obese and have insulin resistance, but nonobese
individuals can also manifest type 2 diabetes (American Diabetes Association, 2004).
Diabetes that is associated with overweight or obesity is sometimes referred to as
diabesity. Approximately 57 million people in the United States, including at least 2
million adolescents, are considered prediabetic and are at risk for developing diabetes
as a result of obesity, sedentary lifestyle, and consumption of an unhealthy diet.
Cardiovascular disease is responsible for approximately 26 percent of the
deaths in the United States each year (Heron et al., 2009). Various terms are used—
cardiovascular disease, heart disease, coronary heart disease, coronary artery disease
(see Glossary)— and each is slightly different. The focus of this section is
atherosclerosis, which is the hardening and narrowing of arteries. Atherosclerotic
heart disease is a life-threatening disease when it occurs in the coronary arteries. The
atherosclerotic process begins in childhood and adolescence with the development of
fatty streaks on the interior walls of arteries. Fatty streaks, which are initially soft,
enlarge and harden and become plaques, which eventually protrude into the lumen of
the artery and may obstruct blood flow (Figure 13.5). Plaques are found between the
middle and inner layers of the coronary arteries and cause them to harden and narrow.
By age 30 most people have fairly well-developed plaques.
Metabolic syndrome (also known as insulin resistance syndrome and
syndrome X) is characterized by a clustering of metabolic disorders and risk factors:
abdominal obesity, hypertension, dyslipidemia including elevated triglycerides and
low HDL-C, glucose intolerance, and insulin resistance (Table 13.7). This disease is
also characterized by proinflammatory and prothrombotic states, which are related to
the development of atherosclerosis and blood clots. Those with metabolic syndrome
have a significantly greater risk of developing cardiovascular disease and type 2
diabetes.
The primary therapeutic approach for those with metabolic syndrome is
lifestyle modification. The specific components of this lifestyle modification are: (1)
increased physical activity, (2) weight reduction, (3) consumption of a diet that
reduces risk for heart disease, and (4) smoking cessation. As discussed previously, the
interaction of diet modification and physical activity/exercise is an important
approach to achieve and maintain a healthy weight. Weight loss, appropriate dietary
modifications, and exercise also work independently and interactively on other risk
factors such as hypertension and dyslipidemia. In addition to lifestyle changes, those
with metabolic syndrome may need pharmacological intervention such as
antihypertensive, lipid-lowering, and antihyperglycemic medications.
The National Osteoporosis Foundation (2005) estimates that approximately 44
million women and men or 55 percent of Americans over the age of 50 have low bone
mineral density (BMD) and are at risk for developing osteoporosis. Osteoporotic
bones are fragile and more prone to fractures, particularly in the spine (vertebrae),
wrist, and hip. A hip fracture in an elderly adult is typically a life-changing event that
may result in the inability to live independently, a living situation that older people
highly value. The key is prevention, and preventative exercise and diet strategies
should be instituted early in life.
One-third of all cancer deaths in the United States are associated with poor
diet, inactivity, and overweight or obesity. This is approximately the same proportion
of deaths associated with tobacco use. Lifestyle plays an important role in reducing
the risk for cancer, and the American Cancer Society (AES) has published diet and
activity guidelines (Kushi et al., 2006). The four major recommendations are: (1)
maintain a healthy weight throughout life, (2) adopt a physically active lifestyle, (3)
consume a healthy diet, with an emphasis on plant sources, and (4) if you drink
alcoholic beverages, limit consumption.
Body Mass Index is the most widely use screening tool for evaluating the risk
of disease based on weight. As discussed in Chapter 11, BMI is inappropriate to use
with athletes, pregnant women, and adults over the age of 65. However, for the
majority of young and middle-aged adults, BMI is a useful screening tool, particularly
for Caucasians. When BMI is used alone, it is not as predictive as when used with
waist circumference, a measure of abdominal body fat. These are widely available and
easily performed screening methods and can be used at health fairs and gyms as well
as in medical settings.
The rapidly rising prevalence of overweight and obesity, as well as the
increase in diseases such as type 2 diabetes and metabolic syndrome, have resulted in
intense media coverage of body weight. A statistic that appeared for many years in
medical journals and in the lay press was that 300,000 deaths in the United States
each year could be attributed to obesity. This Statistic was derived from a study
published by Allison et al. in 1999 using data from 1991. A 2005 study us- ing data
from the year 2000 suggests that the number of obesity-related deaths is much lower
than estimated in the past—approximately 112,000 per year.
It is clear that there is an interaction between physical activity, physical
fitness, obesity, and health. The presence of obesity has multiple negative effects on
long-term health, but being physically active may attenuate some of these effects.
From a health perspective, maintaining a healthy weight is clearly preferable, but if
one is overweight or obese, health benefits can be obtained by being physically active,
even before weight loss occurs. This should not be interpreted to mean that the effect
of obesity is neutralized as long as physical activity is maintained, but it illustrates the
importance of physical activity in reducing health risk relatively quickly. In other
words, people can be positively reinforced by the knowledge that they are
experiencing the health benefits of physical activity long before weight loss might
occur.
Losing body fat is not easy, and maintaining a lower body weight if once
overweight or obese is difficult to sustain. Some health professionals have begun to
question the benefits of traditional weight-loss diets, noting that the prevalence of
obesity is increasing despite overwhelming emphasis on losing excess body fat by the
media and health professionals. Concern has also been raised about the psychological
impact of stressing weight loss in an environment that promotes overeating and
inactivity. Many of those who do successfully lose weight appear to maintain it by
continuing to restrict kilocalories (for example, the Registry), but the psychological
effects of long-term energy restriction is a concern. Some of those who develop
disordered eating and eating disorders have a history of dietary restriction and have
followed numerous weight-loss plans. For all these reasons the nondiet approach or
the Health at Every Size (HAES) movement was born.
