1. Energy Balance and Body Composition
Chapter 8

2. Chapter 8 Objectives
Describe energy balance and the consequences of not being in balance.
Discuss some of the physical, emotional, and environmental influences on food intake.
List the components of energy expenditure and factors that might influence each.
Explain the basal metabolic rate and the factors that affect it.
Discuss the role of physical activity in balancing the energy budget.
Use equations and tables to determine energy requirements.
Distinguish between body weight and body composition, including methods to assess each.
Define healthy body weight.
Explain the methods used to assess body composition, including BMI and waist circumference.
Identify relationships between body weight and chronic diseases.
Identify the health risks for underweight.
Discuss the health risks for overweight, including heart disease, diabetes, and cancer.
Compare and contrast the diagnoses, characteristics, and treatments of the different eating disorders.
Identify eating disorders in the athlete including the female athlete triad and disordered eating.
Discuss the characteristics and the treatment of the eating disorders anorexia nervosa and bulimia nervosa.

3. Energy Balance Excess energy is stored as fat
Healthy-weight person’s fat stores = 50,000 to 200,000 kcalories!
Energy balance: energy in = energy out
A shift in balance causes weight changes
Not simply fat changes
1 pound of fat = 3500 kcalories

4. Energy In: Food Intake Hunger Satiation – stop eating
Physiological response to nerve signals and chemical messengers
Hypothalamus
Influences
Satiation – stop eating
Satiety – not to start eating again

5. Hunger, Satiation, and Satiety

6. Energy In: Food Intake Overriding hunger and satiety External cues
Boredom, anxiety, stress
External cues
Time of day, availability, sight, taste of food
Environmental influences
Cognitive influences
Disordered eating

7. Energy In: Food Intake Sustaining satiation and satiety
Nutrient composition
Protein is most satiating
Low-energy density
High-fiber foods
High-fat foods – strong satiety signals

8. Energy In: Food Intake The hypothalamus Control center for eating
Integrates messages
Energy intake, expenditure, storage
Gastrointestinal hormones

10. Energy Out Components of Energy Expenditure: Basal Metabolism
Physical Activity
Thermic Effect of Food (TEF)
Adaptive Thermogenesis

11. Energy Out: Basal Metabolism
About 2/3 of energy expended in a day
Metabolic activities
All basic processes of life
Basal metabolic rate (BMR)
Variations
Weight
Lean tissue
Resting metabolic rate (RMR)

12. Factors that Affect the BMR

13. Energy Out: Physical Activity
Voluntary movement of skeletal muscles
Most variable component of energy expenditure
Amount of energy needed
Muscle mass
Body weight
Activity
Frequency, intensity, and duration

14. Energy Out: Thermic Effect of Food
Acceleration of GI tract functioning in response to food presence
Releases heat
Approximately 10 percent of energy intake
High-protein foods vs. high-fat foods
Meal consumption time frame

15. Energy Out: Adaptive Thermogenesis
Adapt to dramatically changing circumstances
Examples
Extra work done by body
Amount expended is extremely variable
Not included in energy requirement calculations

16. Components of Energy Expenditure

17. Estimating Energy Requirements
Gender
BMR
Growth
Groups with adjusted energy requirements
Age
Changes with age
Physical activity
Levels of intensity for each gender
Body composition & body size
Height
Weight

19. Body Weight and Body Composition
Body weight = fat + lean tissue (incl water)
Ideal Body Weight: Fashion vs Health
Not appearance based
Perceived body image and actual body size
Damaging behaviors
Subjective
Little in common with health

20. Defining Healthy Body Weight
Body mass index
Relative weight for height
BMI = weight (kg)
height (m)2
Health-related classifications
Healthy weight: BMI = 18.5 to 24.9
Underweight, overweight, obese
Not a measure of body composition
Overweight vs overfat

21. Body Mass Index (BMI)

22. BMI and Body Shapes

23. Distribution of Body Weights in US Adults

24. Body Fat and Its Distribution
Important information for disease risk
How much of weight is fat?
Where is fat located?
Ideal amount of body fat depends on person

25. Body Fat Percentage and Body Shapes

26. Body Fat and Its Distribution
Needing less body fat
Needing more body fat
Fat distribution
Visceral fat
Central obesity
Subcutaneous fat

27. “Apple” and “Pear” Body Shapes Compared

28. Body Fat and Its Distribution
Waist circumference
Indicator of fat distribution & central obesity
Women: greater than 35 inches
Men: greater than 40 inches
Waist-to-hip ratio
Other techniques for body composition
More precise measures

29. Common Methods Used to Assess Body Fat

31. Health Risks Associated with Body Weight & Body Fat
Body weight and fat distribution correlate with disease risk and life expectancy
Correlations are not causes
Risks associated with being underweight
Fighting against wasting diseases
Menstrual irregularities and infertility
Osteoporosis and bone fractures

32. BMI and Mortality

33. Health Risks Associated with Body Weight & Body Fat
Body weight and fat distribution correlate with disease risk and life expectancy
Correlations are not causes
Risks associated with being underweight
Fighting against wasting diseases
Menstrual irregularities and infertility
Osteoporosis and bone fractures

34. Health Risks Associated with Body Weight & Body Fat
Risks associated with being overweight
Obesity is a designated disease
Health risks
More likely to be disabled in later years
Costs
Money
Lives
Yo-yo dieting

35. Health Risks Associated with Body Weight & Body Fat
Cardiovascular disease
Elevated blood cholesterol & hypertension
Central obesity
Diabetes – type II
Weight gains and body weight
Cancer
Relationship is not fully understood

36. Health Risks Associated with Body Weight & Body Fat
Inflammation & metabolic syndrome
Change in body’s metabolism
Cluster of symptoms
Fat accumulation
Inflammation
Elevated blood lipids
Promote inflammation
Fit and fat versus sedentary and slim

37. Eating Disorders
Highlight 8

38. Eating Disorders Three disorders and prevalence Causes
Sociological, psychological, neurochemical
Athletes are among most likely
Disorder
Women
Men
Anorexia Nervosa
0.9%
0.3%
Bulimia Nervosa
1.5%
0.5%
Binge Eating Disorder
3.5% 2%

39. Female Athlete Triad Disordered eating Amenorrhea Osteoporosis
Unsuitable weight standards
Body composition differences
Risk factors for eating disorders in athletes
Amenorrhea
2-5% vs 66%
Osteoporosis
Stress fractures

40. Female Athlete Triad

41. Other Dangerous Practices of Athletes
Muscle dysmorphia
High-protein diets, supplements, weight train for hours, abuse steroids
Similar to other distorted body images
Food deprivation and dehydration practices
Impair physical performance
Reduce muscle strength
Decrease anaerobic power
Reduce endurance capacity

42. Anorexia Nervosa Distorted body image, denial, need for control
Protein-energy malnutrition (PEM)
Similar to marasmus
Impacts brain function and judgment
Causes lethargy, confusion, and delirium
Growth ceases, normal development falters
Changes in heart size and strength
Loss brain tissue, impaired immune response, anemia, GI tract deterioration

43. Anorexia Nervosa Treatment After recovery
Multidisciplinary approach
Food and weight issues
Relationship issues
After recovery
Energy intakes and eating behaviors may not return to normal
High mortality rate among psychiatric disorders

44. Bulimia Nervosa Distinct, more prevalent than anorexia
Secretive, not as physically apparent
Close to ideal weight
Single white female, well-educated
Binge-purge cycle: lack of control
Binge for emotional comfort
Cannot stop, done in secret
Purge
Shame and guilt

45. Bulimia Nervosa Physical consequences of binge-purge cycle
Compromised immune system, fluid/electrolyte imbalances
Tooth erosion, red eyes, calloused hands
Awareness of abnormality
Clinical depression and substance abuse rates are high
Treatment
Learn to eat three meals a day plus snacks
Interdisciplinary team

46. Binge-Eating Disorder
Periodic binging
Compared to bulimia nervosa
Typically no purging, less restrictive dieting
Emotional side is similar
Health risks greater than those of obese people who do not binge
Behavioral disorder responsive to treatment

47. Eating Disorders in Society
Society plays central role in eating disorders
Known only in developed nations
More prevalent as wealth increases
Food becomes plentiful
Body dissatisfaction
Characteristics of disordered eating