1. CHAPTER 8 ENERGY BALANCE AND BODY COMPOSITION

2. ENERGY BALANCE Excess energy is stored as fat Fat is used for energy between meals Energy balance: energy in = energy out A shift in balance causes weight changes 1 pound of fat = 3500 kcalories

3. ENERGY IN: FOOD COMPOSITION Direct measure of food’s energy value – Bomb calorimeter Indirect measure of energy released – Oxygen consumed kCalorie calculations

4. ENERGY IN: FOOD COMPOSITION Appetite prompts a person to eat or not eat Hunger- An irritating feeling that prompts thoughts of food and motivates one to start eating Satiation – tells us to stop eating Satiety – tells us not to start eating again

5. ENERGY IN: FOOD COMPOSITION

6. Overriding hunger and satiety Stress eating External cues Time of day, availability, sight, taste of food Environmental influences Examples Disordered eating

7. ENERGY IN: FOOD COMPOSITION Sustaining satiation and satiety Nutrient composition Protein. low-energy density foods, high-fiber foods, is most satiating High-fat foods – stimulate appetite Complex carbs are satiating promoting

8. ENERGY IN: FOOD COMPOSITION The Hypothalamus Control center for eating Integrates messages Energy intake, expenditure, storage Gastrointestinal hormones

9. ENERGY OUT Thermogenesis Basal metabolism Physical activity Food consumption Adaptation

10. COMPONENTS OF ENERGY EXPENDITURE Basal Metabolism About two-thirds 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. COMPONENTS OF ENERGY EXPENDITURE Physical Activity Voluntary movement of skeletal muscles Most variable & changeable component of energy expenditure Amount of energy needed depends on a few factors

13. COMPONENTS OF ENERGY EXPENDITURE Thermic Effect of Food Acceleration of GI tract functioning in response to food presence Approximately 10 percent of energy intake High-protein foods vs. high-fat foods Meal consumption time frame

14. COMPONENTS OF ENERGY EXPENDITURE Adaptive Thermogenesis Adapt to dramatically changing circumstances Extra work done by body Amount expended is extremely variable & specific to individuals Not included in energy requirement calculations

15. 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

16. DEFINING HEALTHY BODY WEIGHT Ideal Not appearance based Subjective Little in common with health Body mass index Relative weight for height BMI = weight (kg) height (m) 2 Health-related classifications Healthy weight: BMI = 18.5 to 24.9 Other classifications Not a measure of body composition Variations

18. DISTRIBUTION OF BODY WEIGHTS IN U.S. ADULTS

19. 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 General disease risk levels Young men: 22%; Men over 40: 25% Young women: 32%; Women over 40: 35%

20. BODY FAT AND ITS DISTRIBUTION Needing less body fat Needing more body fat Fat distribution Visceral fat Central obesity Subcutaneous fat

21. 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

22. Other techniques for body composition

23. HEALTH RISKS W/ BODY WT & FAT Body weight and fat distribution correlate with disease risk and life expectancy Risks associated with being underweight Fighting against wasting diseases Menstrual irregularities and infertility Osteoporosis and bone fractures Cannot handle medical stresses. Pregnancy problems. Risks associated with being overweight Obesity is a designated disease More likely to be disabled in later years Costs Yo-yo dieting

25. HEALTH RISKS W/ BODY WT & FAT Cardiovascular disease Elevated blood cholesterol & hypertension Central obesity Diabetes – type II Central obesity Insulin resistance Weight gains and body weight Cancer Relationship is not fully understood Inflammation & metabolic syndrome Change in body’s metabolism Fat accumulation Elevated blood lipids