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Chapter8
- 1. Energy BalanceEnergy Balance and Bodyand Body CompositionComposition Chapter 8Chapter 8
- 2. Energy BalanceEnergy 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 CompositionEnergy 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 IntakeEnergy In: Food Intake • Hunger • Physiological response to nerve signals and chemical messengers • Hypothalamus • Influences • Satiation – stop eating • Satiety – not to start eating again
- 5. Hunger, Satiation, and SatietyHunger, Satiation, and Satiety
- 6. Energy In: Food IntakeEnergy In: Food Intake • Overriding hunger and satiety • Stress eating • External cues • Time of day, availability, sight, taste of food • Environmental influences • Examples • Cognitive influences • Disordered eating
- 7. Energy In: Food IntakeEnergy 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 IntakeEnergy In: Food Intake • The hypothalamus • Control center for eating • Integrates messages • Energy intake, expenditure, storage • Gastrointestinal hormones
- 9. Energy OutEnergy Out • Thermogenesis • Basal metabolism • Physical activity • Food consumption • Adaptation
- 10. Energy Out: Basal MetabolismEnergy Out: 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. Factors that Affect the BMRFactors that Affect the BMR
- 12. Energy Out: Physical ActivityEnergy 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
- 13. Energy Out: Thermic Effect ofEnergy Out: Thermic Effect of FoodFood • 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. Energy Out: AdaptiveEnergy Out: Adaptive ThermogenesisThermogenesis • Adapt to dramatically changing circumstances • Examples • Extra work done by body • Amount expended is extremely variable • Not included in energy requirement calculations
- 16. Estimating EnergyEstimating Energy RequirementsRequirements • 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
- 17. Defining Healthy Body WeightDefining Healthy Body Weight • Ideal • Not appearance based • Perceived body image and actual body size • Damaging behaviors • Subjective • Little in common with health
- 18. Tips for Accepting a Healthy Body Weight
- 19. Defining Healthy Body WeightDefining 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
- 20. BMI and Body ShapesBMI and Body Shapes
- 21. Distribution of Body Weights inDistribution of Body Weights in US AdultsUS Adults
- 22. Body Fat and Its DistributionBody 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
- 23. Body Fat and Its DistributionBody 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. ““Apple” and “Pear” BodyApple” and “Pear” Body Shapes ComparedShapes Compared
- 25. Body Fat and Its DistributionBody 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
- 26. Common Methods Used toCommon Methods Used to Assess Body FatAssess Body Fat
- 27. Health Risks Associated withHealth Risks Associated with Body Weight & Body FatBody 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
- 28. BMI and MortalityBMI and Mortality
- 29. Health Risks Associated withHealth Risks Associated with Body Weight & Body FatBody 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
- 30. Health Risks Associated withHealth Risks Associated with Body Weight & Body FatBody 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
- 31. Health Risks Associated withHealth Risks Associated with Body Weight & Body FatBody 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
- 32. Eating DisordersEating Disorders Highlight 8Highlight 8
- 33. Eating DisordersEating Disorders • Three disorders • Anorexia nervosa • Bulimia nervosa • Binge eating disorder • Prevalence of various eating disorders • Causes • Multiple factors • Athletes and eating disorders
- 34. Female Athlete TriadFemale Athlete Triad • Disordered eating • Unsuitable weight standards • Body composition differences • Risk factors for eating disorders in athletes • Amenorrhea • Characteristics • Osteoporosis • Stress fractures
- 35. Female Athlete TriadFemale Athlete Triad
- 36. Other Dangerous Practices ofOther Dangerous Practices of AthletesAthletes • 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
- 37. Tips for Combating Eating Disorders
- 38. Anorexia NervosaAnorexia 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 NervosaAnorexia 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 NervosaAnorexia 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. Bulimia NervosaBulimia 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
- 42. Bulimia NervosaBulimia Nervosa • Binge-purge cycle • Lack of control • Consume food for emotional comfort • Cannot stop • Done in secret • Purge • Cathartic • Emetic • Shame and guilt
- 43. The Vicious Cycle of RestrictiveThe Vicious Cycle of Restrictive Dieting & Binge EatingDieting & Binge Eating
- 45. Bulimia NervosaBulimia 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
- 46. Bulimia NervosaBulimia 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
- 47. Diet Strategies for CombatingDiet Strategies for Combating Bulimia NervosaBulimia Nervosa
- 48. Binge-Eating DisorderBinge-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
- 49. Eating Disorders in SocietyEating 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
Notas do Editor
- Figure H8-2 The Vicious Cycle of Restrictive Dieting and Binge Eating