Energy Balance and Body Composition

1. Energy Balance and Body Composition Chapter 8

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 • Not simply fat 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 • Hunger • Physiological response to nerve signals and chemical messengers • Hypothalamus • Influences • Satiation – stop eating • Satiety – not to start eating again

5. Energy In: Food Composition

6. Energy In: Food Composition • 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 is most satiating • Low-energy density foods are more satiating • High-fiber foods are more satiating • High-fat foods – strong satiety signals

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)

11. Components of Energy Expenditure – Basal Metabolism

12. Components of Energy Expenditure – 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

13. Components of Energy Expenditure – 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

14. Components of Energy Expenditure – Adaptive Thermogenesis • Adapt to dramatically changing circumstances • Examples • Extra work done by body • Amount expended is extremely variable • 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 • Perceived body image and actual body size • Damaging behaviors • Subjective • Little in common with health

17. Defining Healthy Body Weight

18. 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 • Other classifications • Not a measure of body composition • Variations

19. Defining Healthy Body Weight

20. Defining Healthy Body Weight

21. 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%

22. Body Fat and Its Distribution

23. Body Fat and Its Distribution • Needing less body fat • Some athletes • Needing more body fat • Example groups • Fat distribution • Visceral fat • Central obesity • Subcutaneous fat

24. Body Fat and Its Distribution

25. Body Fat and Its Distribution

26. 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

27. Body Fat and Its Distribution

28. 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

29. Health Risks Associated with Body Weight & Body Fat

30. 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

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

32. 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

33. Highlight 8 Eating Disorders

34. Eating Disorders • Three disorders • Anorexia nervosa • Bulimia nervosa • Binge eating disorder • Prevalence of various eating disorders • Causes • Multiple factors • Athletes and eating disorders

35. Female Athlete Triad • Disordered eating • Unsuitable weight standards • Body composition differences • Risk factors for eating disorders in athletes • Amenorrhea • Characteristics • Osteoporosis • Stress fractures

36. Female Athlete Triad

37. Other Dangerous Practices of Athletes • Muscle dysmorphia • Characteristic behaviors • Similarities to others with distorted body images • Food deprivation and dehydration practices • Impair physical performance • Reduce muscle strength • Decrease anaerobic power • Reduce endurance capacity

38. Anorexia Nervosa • Distorted body image • Central to diagnosis • Cannot be self-diagnosed • Malnutrition • Impacts brain function and judgment • Causes lethargy, confusion, and delirium • Denial • Levels are high among anorexics

39. Anorexia Nervosa • Need for self-control • Protein-energy malnutrition (PEM) • Similar to marasmus • Impact on body • Growth ceases and normal development falters • Changes in heart size and strength • Other bodily consequences

40. Anorexia Nervosa • Treatment • 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

41. Anorexia Nervosa

42. Bulimia Nervosa • Distinct and more prevalent than anorexia nervosa • True incidence is difficult to establish • Secretive nature • Not as physically apparent • Common background characteristics of bulimics

43. Bulimia Nervosa • Binge-purge cycle • Lack of control • Consume food for emotional comfort • Cannot stop • Done in secret • Purge • Cathartic • Emetic • Shame and guilt

44. Bulimia Nervosa

45. Negative self-perceptions Restrictive dieting Purging Binge eating Stepped Art Fig. H8-2, p. 266

46. Bulimia Nervosa • Physical consequences of binge-purge cycle • Subclinical malnutrition • Effects • Physical effects • Tooth erosion, red eyes, calloused hands • Clinical depression and substance abuse rates are high

47. Bulimia Nervosa • Treatment • Discontinuing purging and restrictive diet habits • Learn to eat three meals a day • Plus snacks • Treatment team • Length of recovery • Overlap between anorexia nervosa and bulimia nervosa

48. Bulimia Nervosa

49. Binge-Eating Disorder • Periodic binging • Typically no purging • Contrast with bulimia nervosa • Compare with bulimia nervosa • Feelings • Differences between obese binge eaters and obese people who do not binge • Behavioral disorder responsive to treatment

50. 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