Discussion 2 : Highlight: Energy Balance, Fitness and Weight Management

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Weight Management and Energy Balance, Fitness

Chapter 10 & 11

Lecture Outline

What Is a Healthy Weight and Why Is Maintaining It Important?

Healthy weight: body weight relative to height that doesn't increase the risk of developing weight-related health problems or diseases

Weight management: maintaining weight within a healthy range

Overweight: 10 to 15 pounds more than healthy weight

69 percent of Americans are overweight

Obesity: 25 to 40 pounds more than healthy weight

36 percent of Americans are obese

What Is a Healthy Weight and Why Is Maintaining It Important?

Being overweight increases risk of:

Hypertension and stroke

Heart disease

Gallbladder disease

Type 2 diabetes

Osteoarthritis

Some cancers

Sleep apnea

Losing 5 to 10 percent of body weight can produce health benefits

Underweight: weighing too little for your height

May be caused by excessive calorie restriction and/or physical activity, underlying medical condition, emotional stress

Risks for:

Young adults: nutrient deficiencies, electrolyte imbalance, low energy levels, decreased concentration

Older adults: low body protein and fat stores, depressed immune system, medical complications

What's Your BMI?

Figure 10.1

How Do You Know if You're at a Healthy Weight?

Measure your body fat and its location

Average healthy adult male between 20 and 49 years of age: 16 to 21 percent of weight is body fat

Average healthy female: 22 to 26 percent body fat

Techniques to measure body fat include skinfold thickness measurements and bioelectrical impedance

Visceral and Subcutaneous Fat Storage in the Body

Figure 10.2

Measure waist circumference

Central obesity (excess visceral fat) increases risk of heart disease, diabetes, hypertension

Discussion Questions

How can a person who is "normal" weight be at risk for obesity-related diseases?

What are health risks of women who are normal weight obese?

In addition to increased percentage of body fat, what characteristic of body fat points to increased health risks?

Can You Be Slim and Obese? Hidden Risk of Normal Weight Obesity

What Is Energy Balance and What Determines Energy Needs?

Energy balance is calories in versus calories out

Positive energy balance: more calories consumed than expended (leads to fat storage, weight gain)

Negative energy balance: more calories expended than consumed (leads to weight loss)

Energy needs are different for everyone

Energy needs comprise:

Basal metabolism

Thermic effect of food

Physical activities

Energy Balance and Imbalances

Figure 10.5

What Is Energy Balance and What Determines Energy Needs?

Your BMR is the minimum amount of energy you need to function

Amount needed to meet basic physiological needs, keep you alive

Makes up about 60 percent of total energy needs

Many factors affect BMR, chiefly lean body mass

The thermic effect of food affects your energy needs

Amount of calories expended to digest, absorb, and process food (about 10 percent of calories in food eaten)

Physical activity will increase your energy needs

Energy expended by sedentary people = less than half of BMR

Very active athletes can expend twice BMR

Exercise causes small increase in energy expenditure after activity has stopped

Table 10.2

Lean Body Mass

Age

Gender

Body Size

Genes

Ethnicity

Stress

Hormones

Environmental Temperatures

Caffeine

Drugs

What Is Energy Balance and What Determines Energy Needs? Factors that influence BMR

What Is Energy Balance and What Determines Energy Needs?

Calculating your energy needs:

Estimated energy requirement (EER): daily energy need based on age, gender, height, weight, activity level

Energy Imbalances over Time Can Lead to Changes in Body Weight

Reducing calories can lead to weight loss

Stored glycogen and fat are used as fuel sources

Amino acids from body protein breakdown can be used to make glucose

Prolonged fast depletes all liver glycogen

Ketone bodies generated from incomplete breakdown of fat

Fat stores and about one-third of lean tissue mass depleted in about 60 days

Excess calories can lead to weight gain

Excess calories are stored as fat, regardless of source

Limited capacity to store glucose as glycogen

Can't store extra protein

Unlimited capacity to store fat: Body contains about 35 billion fat cells, which can expand

What Factors Are Likely to Affect Body Weight?

Factors in weight management: what and how often you eat, physiology, genetics, environment

Hunger and appetite affect what you eat

Appetite is psychological desire for food

Hunger is physiological need for food; subsides as feeling of satiation sets in. Satiety determines length of time between eating episodes

Physiological mechanisms help regulate hunger

Many hormones play a role:

Ghrelin: produced in stomach when empty; increases hunger

When fat stores increase, leptin in fat tissue signals brain to decrease hunger and food intake.

Cholecystokinin: released when stomach is distended, increasing feelings of satiation, decreasing hunger

Protein, fatty acids, and monosaccharides in small intestine stimulate feedback to brain to decrease hunger

Insulin also causes brain to decrease hunger

Many people override feedback mechanisms, resulting in energy imbalance

What Factors Are Likely to Affect Body Weight?

Genetics partially determines body weight

Risk of becoming obese doubles if parents are overweight, triples if obese, five times greater if severely obese

Confirmed by studies of identical twins separated at birth Genetic differences in level or function of hormones, such as high ghrelin or low leptin levels, increase obesity

Many obese have adequate leptin, but brain has developed resistance to it

Genetic differences in non-exercise-associated thermogenesis (NEAT): energy expenditure in nonexercise movements, such as fidgeting, standing, chewing gum

"Set point" theory holds that body opposes weight loss and works to maintain a set weight

What Factors Are Likely to Affect Body Weight?

Environmental factors can increase appetite and decrease physical activity

Environment of cheap and easily obtainable energy-dense foods stimulates appetite: Gene-environment interaction: increases risk of obesity in some people

We work more and cook less

32 percent of calories come from ready-to-eat foods prepared outside of home

Frequent dining out associated with higher BMI

We eat more (and more)

Increased availability of food-service establishments and access to large variety of foods, larger portions encourage people to eat more

We sit more and move less

Americans are eating about 600 calories/day more than in 1970

Labor-saving devices at work and home, sedentary leisure activities ("screen time") result in decreased energy expenditure

How Can You Lose Weight Healthfully?

National Institutes of Health: overweight individuals should aim to lose about 10 percent of body weight over 6-month period

Example: 180-pound person should lose 18 lb/6 months = 3 lb/month, ¾ lb/week

To lose 1 pound of body fat, need 3,500-calorie deficit

For a weight loss of ½ to 1 lb/week, need to decrease daily calories by 250 to 500 calories

Fad diets promise dramatic results but may carry risks

Eat smart, because calories count: add satiation to low-calorie meals by including higher-volume foods

Eat more vegetables, fruit, and fiber

Include some protein and fat in your meals

Protein increases satiety most

Fat slows movement of food from stomach into intestines

Choose lean meat, skinless chicken, fish, nuts, unsaturated oils

Three Pieces of the Long-Term Weight-Loss Puzzle

Figure 10.8

Adding Volume to Your Meals

Figure 10.9

Table 10.3

The Volume of Food You Eat

Figure 10.10

How Can You Lose Weight Healthfully?

Use MyPlate as a weight-loss guide

High volume of fruits, vegetables, whole grains, some lean protein, modest amounts of fat

Diet should contain variety of foods from all food groups

Replace higher-calorie foods with lower-calorie options from each food group. Example: replace full-fat dairy with nonfat products. Replace sodas with water

Move to lose

45 minutes/day of moderate-intensity activities can prevent becoming overweight and aid in weight loss. 10,000 steps/day can reduce risk of becoming overweight

Break bad habits

Behavior modification: change behaviors that contribute to weight gain or impede weight loss

Techniques include keeping food log, controlling environmental cues that trigger eating, managing stress

Evaluating Popular “ FAD” Diets

Reduction of calories and composition of diet, is key to weight loss

People who diligently adhere to diets lose the most weight. High dropout rates for most extreme diets (Atkins and Ornish diets)

Beware of fad diet claims and hype:

"It's carbs, not calories, that make you fat!"

"Lose seven pounds in one week!"

Celebrity-endorsed miracle weight-loss products

"Natural" substances help lose weight without risk

Best Diet Plan Apparently Works

Discussion Questions

Why do you think the Weight Watchers program has been so successful? What role does social support play in the program?

What are some recommendations or strategies for those who want to lose weight but cannot afford Weight Watchers?

How Can You Maintain Weight Loss?

Weight cycling (repeated gain and loss of body weight) is common result of fad diets

Weight loss can be maintained if healthy habits used during weight loss are maintained

New, lower weight requires fewer calories to maintain weight

Physical activity can close the "energy gap" easier than further reducing caloric intake

Extreme Measures for Extreme Obesity

Gastric bypass and gastric banding result in higher levels of satiety and lower levels of hunger

Results in dramatic weight loss and reduction of hypertension, diabetes, high blood cholesterol, and sleep apnea

Small risk of gallstones, death from surgery

Liposuction is performed for cosmetic reasons

Fat may reappear; results are not permanent

Complications such as infections, scars, swelling

BMI > 40 = extreme obesity

High risk of heart disease, stroke, dying

Requires aggressive weight-loss treatment, including very-low-calorie diets, medications, and/or surgery

Very-low-calorie diets (< 800 calories) are short-term and must be medically supervised

Medications such as Orlistat, Belviq, and Qsymia can't replace a lower-calorie diet, physical activity, and behavior modification

Gastric Bypass and Gastric Binding

Misc 10.14

How Can You Gain Weight Healthfully?

Gaining weight for the underweight is as challenging as losing weight is for the overweight

Need to add at least 500 calories to daily energy intake for gain of 1 pound/week

Choose more energy-dense but nutritious foods from each food group

Examples: waffle instead of toast, coleslaw instead of cabbage

Eat more snacks during day to add more calories

What Is Disordered Eating and What Are the Warning Signs?

Disordered eating: abnormal and potentially harmful eating behaviors that do not meet specific criteria for eating disorders

Eating disorders: psychological illnesses that involve specific abnormal eating behaviors and other factors

In United States, about 20 million women and 10 million men struggle with eating disorders at some point in life. Most are adolescent or young adult white, middle/upper-middle-class females, but increasing among males, minorities, other age-groups

Table 10.5

What Is Disordered Eating and What Are the Warning Signs?

No single factor causes eating disorders

Sociocultural factors

Desire/social pressure to be thin or "cut"

Genetic factors

Eating disorders "run in families"

Psychological factors

Depression, anxiety, perfectionism, sense of control contribute

Factors That Contribute to Eating Disorders

Figure 10.13

What Is Disordered Eating and What Are the Warning Signs?

Anorexia nervosa results from severe calorie restriction

Self-starvation and excessive weight loss

Intense fear of being "fat"

Distorted body image: see oneself as fat when underweight

Health consequences: electrolyte imbalance (low blood potassium) can be fatal

Other risks: decrease in heart rate and blood pressure, lanugo (downy hair), osteoporosis

What Is Disordered Eating and What Are the Warning Signs?

Bulimia nervosa involves cycle of binge eating and purging

Purging can include self-induced vomiting; excessive exercising; strict dieting or fasting; abuse of diet pills, laxatives, diuretics

Vomiting can cause tears in esophagus, swollen parotid glands, tooth decay, gum disease, broken blood vessels in eyes

Potentially fatal electrolyte imbalance can result

Binge eating disorder involves compulsive overeating (without purging)

Eat in secret, feelings of shame

Health effects are those associated with obesity

High blood pressure, cholesterol levels

Risk of heart disease, type 2 diabetes, gallbladder disease

What Is Disordered Eating and What Are the Warning Signs?

Other disordered eating behaviors can be harmful

Orthorexia: "healthy or righteous eating"

Fixation on eating the "right" foods

Night eating syndrome: combination eating, sleep, mood disorder

Person consumes most calories after evening meal, wakes up at night to eat

Pica: desire to consume nonnutritive substances (clay, dirt, chalk)

Can cause medical complications

What Is Disordered Eating and What Are the Warning Signs?

There are some common signs of disordered eating

Hair loss

Significant/sudden weight changes

Russell's sign: scar tissue on knuckles of fingers used to induce vomiting (bulimia nervosa)

Avoiding social situations where food is present

Weighing often, obsessively counting calories

Denial of problem

What Is Disordered Eating and What Are the Warning Signs?

Eating disorders can be treated

Multidisciplinary team approach is most effective

Psychological, medical, and nutrition professionals

Nutritional approaches include:

Identifying binge triggers, safe and unsafe foods, hunger and fullness cues using food journals

Meal plans to ensure adequate calorie/nutrient intake (anorexia nervosa) or to avoid overeating (bulimia nervosa, binge eating disorder)

Best treated in early stages; no "quick fix"

Fitness :Objectives for Chapter 11

List and describe the five basic components of fitness.

Describe the FITT principle and how to use it to create a fitness program.

Describe the roles of carbohydrate, fat, and protein during physical activity.

List optimal food sources before, during, and after exercise.

Describe the importance of vitamins and minerals for physical fitness.

Explain the relationship between fluid intake and fitness.

List and describe ergogenic aids that claim to improve athletic performance and physical fitness.

What Is Physical Fitness and Why Is It Important?

Physical fitness: good health or physical condition, primarily the result of exercise and proper nutrition

Physical fitness has five basic components:

Cardiorespiratory endurance: ability to sustain cardiorespiratory exercise for extended time

Examples: running, biking

Cardiovascular and respiratory systems must provide enough oxygen and energy to muscles

Muscle strength: ability to produce force for brief time

Muscle endurance: ability to exert force for a long period of time without fatigue

Muscle strength and endurance best achieved with weight training

Flexibility: range of motion around a joint

Improved with stretching

Body composition: proportion of muscle, fat, water, and other body tissues that make up body weight

What Is Physical Fitness and Why Is It Important?

Physical fitness provides numerous benefits

Overall health and physical fitness

Reduces risk of cardiovascular disease, type 2 diabetes, and some types of cancer

Improves body composition, bone health, and immune system

Improves sleep and mental well-being

Over half of adults in United States do not meet regular physical activity recommendations

Table 11.1

Table 11.1(continued)

What Does a Physical Fitness Program Look Like?

Cardiorespiratory exercise can improve cardiorespiratory endurance and body composition

Continuous activities that use large muscle groups

Examples: high-impact aerobics, stair climbing, brisk walking

Primarily aerobic because it uses oxygen

Heart rate and stroke volume increased to maximize blood flow delivery to muscles

Reduces risk of heart disease; helps maintain healthy weight and improve body composition

Strength training can improve muscle strength, muscle endurance, and body composition

To increase muscle strength: low number of repetitions using heavy weights

To increase muscle endurance: high number of repetitions using lighter weights

Important to rest between sets of an exercise and between workouts to prevent muscle strains and injury

Stretching can improve flexibility

What Does a Physical Fitness Program Look Like?

The FITT Principle can help you design a fitness program: frequency, intensity, time, type

Rate of perceived exertion (RPE) measures intensity of cardiorespiratory exercise

Target heart rate shows exercise intensity through heart rate (percentage of maximum)

Repetition maximum (RM) refers to intensity of strength training

Physical Activity Guidelines: 60 minutes/week of moderate-intensity activity for some health benefits

60 to 90 minutes daily to lose weight effectively

Table 11.2

Physical Activity Pyramid

Figure 11.1

Table 11.3

The progressive overload principle can help improve fitness over time

The body adapts to physical activities, producing fitness plateau

Modify one or more FITT principles to increase exercise and improve fitness

How Are Carbohydrate, Fat, and Protein Used during Exercise?

Energy during first few minutes of physical activity is provided by anaerobic energy production (without oxygen) from breakdown of:

Adenosine triphosphate (ATP)

Creatine phosphate

Limited amount stored in cells

As exercise continues, oxygen intake and aerobic energy production increase

Carbohydrate (glucose) and fatty acids broken down to yield ATP energy via aerobic metabolism

Energy Metabolism

Figure 11.2

The Energy Currency: ATP

Cori Cycle

Glycolysis

What Fuels Our Activities?

Figure 11.3

How Are Carbohydrate, Fat, and Protein Used during Exercise?

Carbohydrate is the primary energy source during high-intensity exercise

Carbohydrate from blood glucose and stored glycogen in muscle and liver: about 2 hours of exercise

Well-trained muscles store 20 to 50 percent more glycogen than untrained muscles

Liver glycogen maintains normal blood glucose

Lactic acid is produced at high exercise intensities and shuttled to other tissues

Used for energy during low-intensity exercise

How Are Carbohydrate, Fat, and Protein Used during Exercise?

Intensity affects how much glucose and glycogen you use

Glucose and glycogen use increases as intensity increases

How much carbohydrate do you need for exercise?

Depends on duration of activity

During and/or after activity: bananas, bagels, corn flakes that are absorbed quickly

2 hours before exercise: rice, oatmeal, pasta, corn enter blood more slowly for sustained energy

Table 11.4

Carbohydrate Loading

Misc 11.5

How Are Carbohydrate, Fat, and Protein Used during Exercise?

Fat is the primary energy source during low-intensity exercise

Two forms: fatty acids (from triglycerides) in adipose tissue and in muscle tissue

Converting fatty acids into energy is slow and requires more oxygen compared with carbohydrate

How Are Carbohydrate, Fat, and Protein Used during Exercise?

Intensity and training affect how much fat you use

Low-intensity exercise uses mostly fat from adipose tissue

Moderate-intensity exercise also uses fatty acids from muscle triglycerides

Well-trained muscles burn more fat than less trained muscles

Body uses less glycogen and more fat, increases endurance

How Are Carbohydrate, Fat, and Protein Used during Exercise?

How much fat do you need for exercise?

25 to 30 percent of calories should come from fat

Consume unsaturated fats and limit saturated fat to ≤10 percent of total calories

Too little fat (<20 percent) has nutritional risks

How Are Carbohydrate, Fat, and Protein Used during Exercise?

Fat-burning zone: 65 to 73 percent of maximum heart rate

"Cardio" zone: >73 percent of maximum heart rate

Not necessary to stay in fat-burning zone to lose weight

Need to burn calories to produce overall calorie deficit

High-intensity exercise burns calories more quickly but lower-intensity workout can last longer and achieve more

How Are Carbohydrate, Fat, and Protein Used during Exercise?

Protein is primarily needed to build and repair muscle

Muscle damage results from exercise, especially in weight or strength training

Amino acids needed to promote muscle growth and recovery

Body can use protein for energy but prefers carbohydrate and fat as main energy sources

Amino acids are converted to glucose in liver

Endurance athletes need 1.2 to 1.4 g of protein/kg body weight

Resistance/strength activities: 1.2 to 1.7 g/kg body weight

How Are Carbohydrate, Fat, and Protein Used during Exercise?

Total calorie needs depend on the type and schedule of exercise

Timing of meals affects fitness performance

Optimal food choices vary before, during, and after exercise

How Are Carbohydrate, Fat, and Protein Used during Exercise?

Optimal foods before exercise

Allow adequate time for digestion

Large meal: 3 to 4 hours; smaller meals: 2 to 3 hours; snack or liquid supplement: ½ to 1 hour

How Are Carbohydrate, Fat, and Protein Used during Exercise?

Pre-exercise meal: 1 to 4.5 g carbohydrate/kg body weight, 1 to 4 hours before exercise

Carbohydrate 15 to 30 minutes before gives muscles immediate energy, spares glycogen stores, helps reduce muscle damage

Consuming protein before exercise as well as during exercise increases muscle glycogen synthesis and protein synthesis after exercise is over

High-fat foods should be avoided before exercise: take longer to digest, may cause stomach discomfort and sluggishness

How Are Carbohydrate, Fat, and Protein Used during Exercise?

Optimal foods during exercise

For exercise >1 hour, begin carbohydrate intake shortly after start and every 15 to 20 minutes

30 to 60 g carbohydrate/hour to avoid fatigue

Glucose, sucrose, maltodextrin are best choices for quick absorption

Avoid fructose, which can cause GI problems

Consuming both carbohydrate and protein is best for muscle maintenance and growth

How Are Carbohydrate, Fat, and Protein Used during Exercise?

The best way to get both carbohydrate and protein:

Carbohydrate/protein ratio of 3:1 is ideal to promote muscle glycogen and protein synthesis and faster recovery time

Preferred protein choice: whey protein (in milk) is absorbed rapidly and contains all essential amino acids needed

When consuming small snack or liquid supplement after exercise, should have a high-carbohydrate, moderate-protein, low-fat meal within 2 hours

What Vitamins and Minerals Are Important for Fitness?

Vitamins and minerals play major role in metabolism of carbohydrate, fat, and protein for energy during exercise

Some also act as antioxidants and help protect cells from the oxidative stress that can occur with exercise

Antioxidants and cellular damage caused by exercise

Using more oxygen during exercise increases free radicals that damage cells

Supplements of antioxidant vitamins E and C not shown to improve athletic performance or decrease oxidative stress in highly trained athletes

Consume adequate amounts (RDA) from nuts, vegetable oils, broccoli, citrus fruits

What Vitamins and Minerals Are Important for Fitness?

Some minerals can be of concern in highly active people

Iron: Low iron levels can reduce hemoglobin and blood's ability to transport oxygen to cells, causing early fatigue during exercise

Female athletes more at risk for iron-deficiency anemia. Also long-distance runners, those in "make weight" sports and other sports. Iron-rich foods and iron supplements may be needed

"Sports anemia": Decreased hemoglobin can result from strenuous training due to increased blood volume: Not same as iron-deficiency anemia and is self-correcting

Calcium: important to reduce risk of bone fractures

Calcium is lost in sweat

Supplements not recommended unless food intake is inadequate

How Does Fluid Intake Affect Fitness?

Fluid and electrolyte balance and body temperature are affected by exercise

Water is lost through sweat and exhalation

Sodium and chloride, and to a lesser extent potassium, are electrolytes lost in sweat

Electrolyte imbalance can cause heat cramps, nausea, lowered blood pressure, edema

Evaporation of sweat helps cool the body

Hot, humid weather reduces evaporation and body heat increases: increases risk of heat exhaustion and heat stroke

Table 11.5

You need fluids before, during, and after exercise

The American College of Sports Medicine has specific recommendations for how much fluid to drink before and during exercise

Table 11.6

BG: Replace; changes.

Some Beverages Are Better Than Others

Sports drinks contain 6 to 8 percent carbohydrate and sodium and potassium: beneficial in long endurance events

For events <60 minutes, water is sufficient to replace fluids, and postexercise food will replace electrolytes

Sports drinks should be avoided as a daily beverage: damage tooth enamel, provide unwanted calories

Not recommended during physical activity: fruit juice (too high carbohydrate concentration); carbonated drinks (bloating); alcohol and caffeine (diuretics, unwanted side effects)

Sports Drinks Science: Is It Hype?

Discussion Questions:

How does the marketing of products, including product placement, impact sales?

Discuss the problems with the science behind the sports drinks. Discuss whether or not it is ethical for companies to pay for research on their own products.

Identify claims sports drink companies have published that may bend the truth.

Why might sports drinks be unhealthy for your weekend warrior or average gym goer?

Effects of Dehydration on Exercise Performance

Figure 11.4

Thirst is not a good indicator of fluid needs for athletes

Acute dehydration: when not adequately hydrated before strenuous exercise

Chronic dehydration: when not adequately hydrated over extended period of time

Fatigue, muscle soreness, poor recovery from workout, headaches, nausea, dark urine

Hyponatremia: low sodium blood levels due to consuming too much water without electrolytes

Can Dietary Supplements Contribute to Fitness?

Dietary supplements are not strictly regulated by FDA

Manufacturers not required to prove safety or efficacy of supplement claims

Dietary supplements and ergogenic aids may improve performance, but can have side effects

Creatine: research data mixed on enhancement of performance. Improves high-intensity, short-duration activities (like weight training) that rely on anaerobic metabolism.

Caffeine enhances athletic performance, mostly during endurance events.

Stimulates central nervous system, breakdown of muscle glycogen, may increase fatty acid availability

Considered a banned substance by some athletic associations

Can Dietary Supplements Contribute to Fitness?

Anabolic steroids: testosterone-based substances that promote muscle growth and strength (anabolic effect)

Androgenic effect (testosterone-promoting): hormone imbalance causes undesirable side effects in both men and women; also health risks

Growth hormone: little research on effects on athletic performance, results mixed

Reduces body fat but not muscle strength

Excess can cause acromegaly and serious health issues

Erythropoietin and blood doping: to increase oxygen-carrying capacity of the blood

Can increase blood viscosity, increase risk of stroke and heart attack

Table 11.7

Table 11.7 (continued)

Can Dietary Supplements Contribute to Fitness?

Sports bars, shakes, and meal replacers may provide benefits

The main energy source in most sports bars and shakes is carbohydrate, with protein and fat contributing smaller amounts of energy

Convenient alternative, but more expensive than whole foods

Often include vitamins and minerals, which may be unneeded

Table 11.8

"No Oven Needed " Energy Bars

Figure 11.5