Energy Balance and Body Composition
I.
Energy Balance
Body weight is stable when energy consumed is equal to energy expended. When energy
consumed is greater than expended, weight increases. When energy consumed is less than
expended, weight decreases. One pound of body weight is equal to 3,500 kcalories.
II. Energy In: The kCalories Foods Provide
Eating behaviors respond to different signals. Hunger and appetite encourage eating, while
satiation and satiety stop eating. Messages are sent from the hormonal and nervous system.
Other aspects of human behavior affect eating habits.
A. Food Composition
1. A bomb calorimeter is an instrument that measures the heat energy released when
foods are burned.
2. Direct calorimetry measures the heat energy released.
3. Indirect calorimetry measures the amount of oxygen consumed and carbon dioxide
expelled.
4. Physiological fuel value is the difference between the number of kcalories measured
with calorimetry and the number of kcalories that the human body derives from a
food.
B. Food Intake
1. Appetite initiates eating through the sight, smell, thought or taste of food.
2. Hunger is the feeling that motivates us to eat and is controlled by the hypothalamus.
3. Satiation is the feeling of satisfaction and fullness that causes us to stop eating.
4. Satiety reminds us not to eat again until the body needs food.
5. Overriding Hunger and Satiety
a. Stress eating is eating in response to arousal.
b. Cognitive influences such as perceptions, memories, intellect, and social
interactions
6. Sustaining Hunger and Satiety
a. Protein is the most satiating.
b. Complex carbohydrates are satiating.
c. High-fat foods stimulate and entice people to eat more.
7. Message Central—The Hypothalamus
a. Integrates messages about energy intake, expenditure, and storage
b. Neuropeptide Y initiates eating, decreases energy expenditure, increases fat
storage and causes carbohydrate cravings.
C. Components of Energy Intake
1. Type of Energy; Carbohydrate vs. Fat
2. Timing of energy intake; Early vs. late
3. Amount at one time
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III. Energy Out: The kCalories the Body Expends
Energy expenditure includes basal metabolic activities, physical activity, thermic effect of
food and adaptive thermogenesis. These energy requirements differ from person to person
and are affected by age, gender, weight, and height. The intensity and duration of physical
activity also make a difference.
A. Components of Energy Expenditure
1. Basal Metabolism (basal metabolic rate, BMR)
a. 2/3 of energy expenditure
b. Supports the basic processes of life
c. Resting metabolic rate (RMR) is a measure of energy slightly higher than BMR.
d. Factors affecting BMR
1. Aging slows BMR
2. Height – the taller, the higher the BMR
3. Growth increases BMR.
4. Body composition (lean body mass increases BMR)
5. Fever increases BMR.
6. Stress increases BMR.
7. Environmental temperature - both heat and cold raise BMR
8. Fasting/starvation slows BMR.
9. Malnutrition slows BMR.
10. Hormones
a. Thyroid hormones can increase or decrease BMR.
b. Premenstrual hormones can increase BMR.
11. Smoking increases BMR.
12. Caffeine increases BMR.
13. Sleep slows BMR.
2. Physical activity
a. Most variable and changeable
b. Voluntary
c. It can be significant in weight loss and weight gain.
d. Frequency, Intensity and Time/duration, influence energy expenditure.
3. Thermic effect of food (TEF) is estimated at 10% of total energy intake and involves
digestion and absorption.
a. Carbohydrate 5-10%
b. Fat 0-5%
c. Protein 20-30%
d. Alcohol 15-20%
4. Adaptive thermogenesis is the adjustment in energy expenditure related to
environmental changes.
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B. Estimating energy requirements is affected by many factors.
1. Gender – men generally have a higher BMR
2. Growth – BMR is high in people who are growing
3. Age – BMR declines as lean body mass decreases
4. Physical activity – Activities are clustered by intensity and vary considerably
5. Body composition and body size – taller people have more surface area and heavier people
have higher BMRs
IV. Body Weight, Body Composition, and Health
Current weight standards use height and weight data and do not take body composition into
consideration. These may be misleading.
A. Defining Healthy Body Weight
1. The Criterion of Fashion
a. Society values change over time.
b. Perceived body images
2. The Criterion of Health
a. Good health supercedes appearance.
b. Longevity is a criterion.
3. Body mass index (BMI) measures relative weight for height.
a. Underweight is a BMI below 18.5.
b. Overweight is a BMI above 25.
c. Obese is a BMI above 30.
d. Severely Obese is a BMI above 35
B. Body Fat and Its Distribution
1. Some People Need Less Body Fat
a. Fat for fuel
b. Fat for insulation and protection
c. Fat to assist in nerve impulse transmissions
d. Fat to support normal hormone activity
2. Some People Need More Body Fat
a. Thresholds differ among individuals
b. Thresholds differ for each function
3. Fat Distribution
a. Intra-abdominal fat around abdominal organs may be critical.
b. Central obesity is excess fat around the trunk of the body. It is also called
abdominal fat or upper-body fat.
c. Associated with increased risks
4. Waist Circumference
a. Practical indicator of fat distribution and abdominal fat
b.  35 is considered high risk for women.
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c.  40 is considered high risk for men.
5. Measures of Body Composition
a. Monitoring changes over time is important.
b. Fatfold measures
c. Hydrodensitometry
d. Bioelectrical impedance
e. Air displacement plethysmography
f. Dual energy X-ray absorptiometry (DEXA)
C. Health Risks Associated with Body Weight and Body Fat – An appropriate weight for an
individual depends on many factors which include body fat distribution, health history
and current state of health.
1. Health Risks of Underweight
a. Cannot handle medical stresses
b. Menstrual irregularities and infertility
c. Pregnancy problems
d. Osteoporosis and bone fractures
2. Health Risks of Overweight
a. Diabetes
b. Hypertension
c. Cardiovascular disease
d. Sleep apnea
e. Osteoarthritis
f. Some cancers
g. Gallbladder disease
h. Kidney disease
i. Respiratory problems – Pickwickian syndrome
j. Complications in pregnancy and surgery
3. Cardiovascular disease and obesity have a strong relationship.
4. Diabetes and obesity have a strong relationship.
a. Insulin resistance and obesity have a strong relationship.
5. Inflammation and the Metabolic Syndrome
a. High blood pressure
b. High blood glucose
c. High blood triglycerides
d. Low HDL cholesterol
e. High waist circumference
6. Cancer risk increases with weight gain but the relationship is unclear.
7. Fit and Fat versus Sedentary and Slim
a. Healthy weight is important.
b. Cardiorespiratory fitness is important.
V. Eating Disorders
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Many individuals, including young females, suffer from eating disorders. These include
anorexia nervosa, bulimia nervosa and binge-eating disorders. The causes include a
combination of sociocultural, psychological, and perhaps neurochemical factors. Athletes are
among the most likely group to develop eating disorders.
A. The Female Athlete Triad
1. Disordered eating habits can develop.
a. Desire to improve performance
b. Enhance aesthetic appeal of their performance
c. Meet unsuitable weight standards
2. Amenorrhea
a. Characterized by low blood estrogen, infertility, and mineral losses from the bone
b. Contributors include excessive training, depleted body fat, low body weight, and
inadequate nutrition.
c. Primary amenorrhea – menarche delayed beyond 16 years of age
d. Secondary amenorrhea – absence of three to six consecutive menstrual cycles
3. Osteoporosis
a. Stress hormones compromise bone health.
b. Stress fractures are common bone injuries.
c. Adequate calcium is recommended.
B. Other Dangerous Practices of Athletes
1. Food and fluid restrictions to make weight in wrestling
2. Muscle dysmorphia is a psychiatric disorder concerning obsession with building
body mass.
C. Preventing Eating Disorders in Athletes
1. Follow USDA Food Guide for food servings.
2. Eat frequently, especially healthy snacks.
3. Establish a reasonable weight goal.
4. Allow reasonable time to achieve the weight goal.
5. Join a weight maintenance support group.
D. Anorexia Nervosa
1. Characteristics of Anorexia Nervosa
a. Self-starvation – tremendous self-control to limit eating
b. Physical consequences are major and life threatening.
2. Treatment is multidisciplinary
a. Food and weight
b. Relationships with self and others
E. Bulimia Nervosa
1. Characteristics of Bulimia Nervosa
a. Binge eating – lack of control over eating, excessive kcalories from high-fat, lowfiber and high-carbohydrate foods eaten all at once
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b. Purging – cathartic and/or emetic
2. Treatment of Bulimia Nervosa
a. Weight maintenance
b. Regular exercise
c. Counseling
F. Binge-Eating Disorder is an unspecified eating disorder sharing some of the
characteristics of anorexia nervosa and bulimia nervosa yet does not meet the criteria for
diagnosis.
1. Lack of self-control over eating with binges
2. Consuming large quantities of food, eating quickly, feeling uncomfortably full, eating
alone, and feeling disgusted or guilty
3. Marked distress
4. Occurrence of two times per week for six months
5. Not associated with compensatory behaviors
G. Eating Disorders in Society – occur more commonly in developed nations where food
and money are plentiful. Learning to appreciate the uniqueness of oneself may be a key to
prevention.
1.
What are the consequences of an unbalanced energy budget?
2.
Define hunger, appetite, satiation, and satiety and describe how each influences food intake.

Hunger is the physiological need for food;

Appetite is the psychological desire for food.

Satiation is the feeling of satisfaction and fullness that occurs during a meal and halts eating;

Satiety is a feeling of fullness after a meal.
Hunger and appetite are likely to increase food intake. Satiation determines how much food is consumed
during a meal. Satiety inhibits eating until the next meal; it determines how much time passes between
meals. A high level of satiety is likely to decrease food intake between meals.
3.
Describe each component of energy expenditure. What factors influence each? How can energy
expenditure be estimated?
Basal metabolism: energy needed to maintain life when a body is at complete rest.
Physical activity: voluntary movement of the skeletal muscles and support systems.
Thermic effect of food: energy required to process food. See “How to Estimate Energy Requirements” box
for specific equations.
4.
5.
Distinguish between body weight and body composition. What assessment techniques are used to
measure each?
.
What problems are involved in defining “ideal” body weight?
6.
What is central obesity and what is its relationship to disease?
7.
What risks are associated with excess body weight and excess body fat?
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.Body
Mass Index (BMI): Reality vs. Myths
Reality
If your BMI > 25 you are considered to be overweight.
If your BMI > 30 you are considered to be clinically
obese.
If your BMI is within a healthy range, then you are
considered to be at the right weight for your given
height.
If your BMI < 18.5 you are considered to be
underweight.
Myth
Only a high BMI affects health status.
You only have to worry when your BMI > 40 because
only then you are considered to be morbidly obese.
If your BMI is within a healthy range (18.5 – 24.9) then
you don’t have to worry about any health problems.
Only a low BMI affects health status.
Medical Problems Associated with Obesity

Hypertension

Renal Disease

Gallbladder Disease

Pulmonary Disease

Problems With Anesthesia During Surgery

Osteoarthritis and Gout

Breast and Endometrial Cancer

Abnormal Plasma Lipid and Lipoprotein Concentrations

Impairment of Cardiac Function

Menstrual Irregularities and Toxemia of Pregnancy

Psychological Trauma

Flat Feet and Infection in Fatfolds

Organ Compression by Adipose Tissue

Impaired Heat Tolerance
Source: Art Gilbert, Director, Wellness Fitness Institute, University of California, Santa Barbara, with permission.
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