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Energy balance ch7


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Energy balance ch7

  1. 1. Weight Maintenance
  2. 2. The STATS <ul><li>60% of U.S. adults are overweight </li></ul><ul><ul><li>~40% of these are obese </li></ul></ul><ul><li>Childhood obesity is on the rise </li></ul><ul><li>Chronic diseases, morbidity, mortality associated with weight increasing </li></ul>
  3. 3. Energy Balance <ul><li>Positive energy balance: </li></ul><ul><ul><li>Energy in > energy out </li></ul></ul><ul><li>Negative energy balance: </li></ul><ul><ul><li>Energy in < energy out </li></ul></ul><ul><li>Energy balance: </li></ul><ul><ul><li>Energy in = energy out </li></ul></ul>
  4. 4. Nutrients in Energy Balance <ul><li>CHO is first choice for energy use in body </li></ul><ul><li>Fat is preferentially stored </li></ul><ul><li>Excess CHO and protein in diet  decreased use of fat for energy and increased fat storage </li></ul><ul><li>Animals in lab studies fed high-fat diets tend to gain more weight than controls </li></ul>
  5. 5. Questions? <ul><li>Why might higher fat intake contribute to fat storage and weight gain? </li></ul><ul><li>Why does excess CHO and protein consumption contribute to fat storage and weight gain? </li></ul>
  6. 6. Energy Output <ul><li>Three factors: </li></ul><ul><ul><li>Basal metabolism (60-70%) </li></ul></ul><ul><ul><li>Physical activity (up to 25-40%) </li></ul></ul><ul><ul><li>Thermic effect of food (5-10%) </li></ul></ul>
  7. 7. Basal Metabolism <ul><li>Basal metabolic rate (BMR) = minimum energy needed to support the body in a fasted, resting (awake), warm, quiet environment </li></ul><ul><li>BMR: </li></ul><ul><ul><li>For men = 1 kcal/kg/hr </li></ul></ul><ul><ul><li>For women = 0.9 kcal/kg/hr </li></ul></ul>
  8. 8. Factors Affecting BMR <ul><li>Lean body mass (non-fat body tissue) increases BMR </li></ul><ul><ul><li>Organs and muscle are “metabolically active” organs, particularly compared to adipose </li></ul></ul><ul><li>Body surface area  increases BMR </li></ul><ul><ul><li>More heat loss </li></ul></ul><ul><li>Gender : </li></ul><ul><ul><li>Males have higher BMR related to lean body mass </li></ul></ul><ul><ul><ul><li>Healthy body fat composition: </li></ul></ul></ul><ul><ul><ul><ul><li>8-25% for males, 20-35% for females </li></ul></ul></ul></ul>
  9. 9. Factors Affecting BMR <ul><li>Body temperature (fever and cold)  increases BMR </li></ul><ul><ul><li>Fever/sweating and cold/shivering </li></ul></ul><ul><li>Thyroid hormones directly increase BMR </li></ul><ul><ul><li>??Why can hypothyroidism lead to weight gain?? </li></ul></ul><ul><li>Some nervous system activity </li></ul><ul><li>Age  decreased BMR (associated with diminished lean body mass) </li></ul>
  10. 10. Factors Affecting BMR <ul><li>Nutritional state </li></ul><ul><ul><li>Starvation  decreases BMR to conserve energy (up to 10-20%!) </li></ul></ul><ul><ul><li>Dieting  decreases BMR to conserve energy </li></ul></ul><ul><ul><ul><li>??When someone ends a diet program and returns to normal eating patterns, why is it easy to gain the weight back so quickly?? </li></ul></ul></ul><ul><ul><li>Pregnancy increases BMR </li></ul></ul><ul><ul><li>Caffeine and tobacco use increases BMR </li></ul></ul><ul><ul><ul><li>??Why should smoking cessation be accompanied by a weight control plan?? </li></ul></ul></ul>
  11. 11. Physical Activity <ul><li>Can increase energy expenditure up to 25-40% above basal energy needs </li></ul><ul><li>Barriers: </li></ul><ul><ul><li>Sedentary jobs/desk jobs, school, sedentary recreation activities (TV, internet), safety </li></ul></ul><ul><li>Helpful strategies: </li></ul><ul><ul><li>Stairs instead of elevator, walk or bike instead of drive, park farther away and walk, pace when on phone </li></ul></ul>
  12. 12. Physical Activity <ul><li>Nonexercise activity thermogenesis </li></ul><ul><ul><li>Fidgeting increases energy expenditure </li></ul></ul><ul><ul><li>In some people, overeating triggers involuntary fidgeting, maintenance of muscle tone and body posture </li></ul></ul>
  13. 13. Thermic Effect of Food <ul><li>Energy required to digest, absorb, and use/metabolize food nutrients </li></ul><ul><li>5-10% of total energy expenditure </li></ul><ul><li>TEF higher for CHO and protein-rich meals than for fat-rich meals </li></ul><ul><ul><li>Takes less energy to place absorbed fat into adipose stores than to metabolize CHO into glycogen and excess amino acids into fat </li></ul></ul>
  14. 14. “ Healthy” Weight <ul><li>Fitness = ability to perform an activity without undue fatigue </li></ul><ul><li>A sedentary person may be at higher risk for cardiovascular disease than a fit, overweight person </li></ul><ul><li>Cultural “ideal” weight vs. “healthy” weight </li></ul><ul><ul><li>Can you think of ways that printed and digital media contribute to the perception of ideal body size in our culture? </li></ul></ul>
  15. 15. Determining Body Fat Composition <ul><li>Anthropometrics – skinfold thickness test </li></ul><ul><li>Bioelectrical impedance – fat resists electrical flow </li></ul><ul><li>Underwater weighing – gold standard, “fat floats” </li></ul><ul><li>Bod Pod – air displacement, like UWW </li></ul><ul><li>DEXA scan – full body x-ray scan </li></ul>
  16. 16. Fig. 7.11 Fig. 7.12 Fig. 7.13 Fig. 7.9
  17. 17. Body Mass Index (BMI) <ul><li>Scale associating height and weight with health risk </li></ul><ul><li>BMI = (wt in kg)/(ht in meters)^2 </li></ul><ul><li>Scale: </li></ul><ul><ul><li><19 = health risk from underweight </li></ul></ul><ul><ul><li>20-25 = ideal body weight </li></ul></ul><ul><ul><li>25-30 = overweight, some risk for obesity and related health problems </li></ul></ul><ul><ul><li>30+ = obesity, health risk </li></ul></ul><ul><ul><li>40+ = severe health risk </li></ul></ul>
  18. 18. Fig. 7.8
  19. 19. Problems Associated with Excess Body Fat <ul><li>Surgery risk, anesthesia needs, wound infections </li></ul><ul><li>Pulmonary disease, sleep disorders </li></ul><ul><li>Cardiovascular disease </li></ul><ul><li>Hypertension </li></ul><ul><li>Type 2 diabetes </li></ul><ul><li>Bone and joint disorders </li></ul><ul><li>Gallstones </li></ul>
  20. 20. Problems Associated with Excess Body Fat <ul><li>Skin disorders </li></ul><ul><li>Decreased physical agility, increased risk for accidents and falls </li></ul><ul><li>Some cancers (breast, colon, pancreas, gall bladder) </li></ul><ul><li>Early puberty  short stature, complications in growth </li></ul><ul><li>Menstrual irregularities, infertility </li></ul><ul><li>Pregnancy risks </li></ul><ul><li>Premature death </li></ul>
  21. 21. Body Fat Distribution <ul><li>Upper body (android or abdominal obesity) = “apple” shape </li></ul><ul><ul><li>Typical male pattern, encouraged by testosterone, alcohol, yo-yo dieting </li></ul></ul><ul><ul><li>Higher health risk for cardiovascular disease, hypertension, type 2 diabetes </li></ul></ul><ul><ul><li>Waist circumference over 40” for men, 35” for women </li></ul></ul><ul><li>Lower body (gynoid) = “pear” shape </li></ul><ul><ul><li>Characteristic female pattern </li></ul></ul><ul><ul><li>Less health risk </li></ul></ul>
  22. 22. Body Fat Distribution Fig. 7.14
  23. 23. Nature vs. Nurture <ul><li>Some genetic predisposition </li></ul><ul><li>Environmental influences: </li></ul><ul><ul><li>Sedentary jobs </li></ul></ul><ul><ul><li>Sedentary leisure activities </li></ul></ul><ul><ul><li>Safety </li></ul></ul><ul><ul><li>Time pressures </li></ul></ul><ul><ul><li>Pre-prepared, processed convenience foods </li></ul></ul><ul><ul><li>Overeating habits </li></ul></ul>
  24. 24. Treatment for Overweight <ul><li>Requires long-term lifestyle changes </li></ul><ul><ul><li>Diet modification </li></ul></ul><ul><ul><li>Regular physical activity </li></ul></ul><ul><li>Sensible weight loss program: </li></ul><ul><ul><li>No more than 2 pounds per week </li></ul></ul><ul><ul><li>3500 kcal deficit = 1 pound weight loss </li></ul></ul><ul><ul><li>1 pound/week = 500 kcal deficit </li></ul></ul><ul><ul><li>2 pounds/week = 1000 kcal deficit </li></ul></ul><ul><ul><li>No less than 1600 kcal per day total to avoid nutrient deficiencies, metabolic disturbances </li></ul></ul><ul><ul><li>Strategy: split Calorie deficit between diet and exercise </li></ul></ul>
  25. 25. Treatment for Overweight <ul><li>Commercial diet plans </li></ul><ul><ul><li>Only about 5% success rate </li></ul></ul><ul><ul><li>Most regain weight in 3-5 years </li></ul></ul><ul><ul><li>Weight cycling (“yo-yo dieting”)  increased risk for upper body fat accumulation, possibly lowered HDL, negative effect on emotions/self image </li></ul></ul>
  26. 26. Treatment for Overweight <ul><li>Medical intervention: </li></ul><ul><ul><li>Rx – short-term only, sometimes do not work, severe side effects </li></ul></ul><ul><ul><li>Very low Calorie diet – 400-800 kcal/day with most from high quality protein </li></ul></ul><ul><ul><ul><li>Requires careful MD monitoring </li></ul></ul></ul><ul><ul><ul><li>May cause ketosis, heart problems, gallstones, nutrient deficiencies, metabolic disturbances </li></ul></ul></ul><ul><ul><ul><li>Regain of weight possible </li></ul></ul></ul><ul><ul><li>Surgery – stomach “stapling” or bariatric surgery </li></ul></ul><ul><ul><ul><li>Permanent effect on GI system, metabolism, risk for nutrient deficiencies </li></ul></ul></ul>