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Chapter 22

Chapter 22. Obesity, Diabetes, and Physical Activity. Chapter 22 Overview. Obesity Terminology Prevalence Control of body weight Etiology Health problems Treatment Physical activity. Diabetes Terminology Prevalence Etiology Health problems Treatment Physical activity.

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Chapter 22

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  1. Chapter 22 • Obesity, Diabetes, and Physical Activity

  2. Chapter 22 Overview • Obesity • Terminology • Prevalence • Control of body weight • Etiology • Health problems • Treatment • Physical activity • Diabetes • Terminology • Prevalence • Etiology • Health problems • Treatment • Physical activity

  3. Obesity:Terminology and Classification • Overweight • Body weight exceeds standard weight for given height and frame size • Not precise terminology • Does not account for body composition • Obesity • Excessive body fat (men >25%, women >35%) • Borderline obese: men 20 to 25%, women 30 to 35%

  4. Obesity:Terminology and Classification • Body mass index (BMI) • Body weight in kilograms/(height in m)2 • Most widely used standard for obesity classification • Does not account for body composition • Overweight: 25.0 to 29.9 kg/m2 • Obese: 30.0+ kg/m2 • BMI classification cut points change for difference races and ethnicities

  5. Table 22.2

  6. Obesity:Prevalence in the United States • Prevalence  dramatically since ~1980 • Prevalence of overweight has not changed much • Obesity continues to increase • More prevalent in some races and ethnicities • Mexican-American men • Black women • Increasing prevalence in children and teens

  7. Figure 22.1a

  8. Figure 22.1b

  9. Figure 22.1c

  10. Figure 22.2

  11. Figure 22.3

  12. Obesity:Prevalence in the United States • With age: fat mass , lean body mass  • Over age 25, average person gains ~0.7 to 1 lb per year • Up to 33 extra lb by age 55 • Will have significant effect on health care • Earlier onset of obesity • Increasing rates of obesity • Earlier onset of obesity-related diseases

  13. Obesity: Worldwide Prevalence • Increases in obesity not unique to United States • Canada, Australia, Europe have seen increases to a lesser degree • Available data vary • Most recent studies show obesity spreading to all regions of the world

  14. Table 22.3

  15. Obesity:Control of Body Weight • Body usually carefully balances kilocalorie intake and expenditure • Gain of 1 lb/year represents imbalance of 3,111 kcal per year • Body can balance to within 9 kcal per day • Body may regulate around set point using • Resting metabolic rate (RMR) • Thermal effect of meals (TEM) • Thermal effect of activity (TEA)

  16. Obesity:Control of Body Weight • RMR • Body’s metabolic rate in the early morning • 60 to 75% of total energy expenditure • TEM • Energy expended to digest, store nutrients, etc. • 10% of total energy expenditure • May be defective in obese individuals

  17. Obesity:Control of Body Weight • TEA • Energy expended to accomplish activities • 15 to 30% of total energy expenditure • Balance of RMR, TEM, TEA • Helps body adapt to  or  kilocalorie intake • Controlled by sympathetic nervous system • Key for maintaining weight around set point

  18. Figure 22.4

  19. Obesity:Control of Body Weight • Set point regulation versus weight gain • Diet composition alters set point • Physical activity alters set point • High-fat diets usually  overfeeding • Other factors • Larger portions/restaurant supersizing • Higher fat consumption • More eating away from home

  20. Obesity:Etiology • Physiological factors • Heredity/genetics • Hormonal imbalances • Altered basic homeostatic mechanisms • Lifestyle factors • Cultural habits • Inadequate physical activity • Improper diets

  21. Figure 22.5

  22. Obesity:Health Problems • Morbidity: presence or rate of disease • Mortality: death from disease • Obesity and overweight   mortality • Major increased risk: BMI >35

  23. Figure 22.6

  24. Obesity:Health Problems • Obesity and overweight associated with • Cardiovascular disease • Type 2 diabetes • Cancer (endometrial, breast, colon) • Liver, gallbladder disease • Osteoarthritis • Sleep apnea • Metabolic syndrome rate parallels obesity

  25. Obesity: Genetic Versus Lifestyle Effects • Pima Indians: study in genetics versus lifestyle • Native lifestyle  lean and healthy • Western diet/lifestyle  high rates of obesity • Men: 64% • Women: 75% • Obesity often accompanied by diabetes • Men: 34% • Women: 41%

  26. Obesity: Genetic Versus Lifestyle Effects

  27. Obesity:Health Problems • Changes in normal body function • Vary with individual • Vary with degree of obesity • Lethargy • Polycythemia • Low blood O2/high blood CO2 • Clotting, heart failure

  28. Obesity:Health Problems • Body fat distribution: disease risk factor • Upper-body (android) obesity (men) • Lower-body (gynoid) obesity (women) • Waist:hip girth ratio and visceral fat index identify fat distribution • Android obesity  higher risk for • Cardiovascular disease • Elevated blood lipids • Diabetes

  29. Figure 22.7

  30. Figure 22.8a

  31. Figure 22.8b-c

  32. Obesity:Health Problems • Exacerbates existing diseases • Weight loss reduces severity of • Angina pectoris • Hypertension • Congestive heart disease • Heart attack recurrence • Varicose veins • Diabetes • Orthopedic problems

  33. Obesity:Health Problems • Emotional and psychological factors • Can help cause obesity • Can be exacerbated by obesity • Obesity = social stigma • Media glamorize thin people • But norms may shift as obesity becomes more common

  34. Obesity:General Treatment • Weight loss = kilocalorie intake < kilocalorie expenditure • Oversimplification • Weight loss treatment multifactorial • Loss not to exceed 1 to 2 lb per week • Weight loss a long-term project • Maintain balanced diet with caloric deficit • Reduce intake of fat and simple sugars

  35. Obesity:General Treatment • Hormone treatments • Decrease appetite • Increase RMR • Serious side effects, life threatening • Surgical treatments • Intestinal bypass • Gastric banding or bypass • Reserved for most extreme, serious cases

  36. Obesity:General Treatment • Behavior modification: change in eating patterns or habits. Examples: • Can only eat in one location • No snacking • No second helpings • Appealing, simple weight loss approach

  37. Obesity: Role of Physical Activity in Weight Control • Overeating and inactivity: major causes of obesity • Kilocalorie restriction and exercise best treatments • Exercise alters body composition • Significant long-term kilocalorie deficit • Significant long-term fat loss • EPOC   postexercise metabolism

  38. Obesity: Role of Physical Activity in Weight Control • Body mass and composition changes with exercise –  Total weight –  Fat mass, percent body fat • Maintained or  FFM • Changes long term (6-12 months)

  39. Table 22.4

  40. Obesity: Role of Physical Activity in Weight Control • Both aerobic and resistance training  weight loss • Exercise important aspect of weight loss • Must combine exercise + kilocalorie restriction • Decrease rate of visceral fat accumulation • Energy balance equation • Kilocalorie intake – kilocalories excreted = (RMR + TEM + TEA) • Helps clarify weight loss mechanisms

  41. Obesity: Role of Physical Activity in Weight Control • Exercise effects on appetite • Leads to appetite suppression in male animals • Leads to no change or  intake in female animals • Less activity ≠ less food intake • Causes for appetite suppression • Higher circulating catecholamines • Higher body temperature

  42. Obesity: Role of Physical Activity in Weight Control • Exercise effects on RMR • May increase with training • Resistance training of interest (RMR related to FFM) • Exercise effects on TEM • Pre- and postmeal exercise   TEM • Chronic exercise training  inconclusive • Exercise effects on fat mobilization • During exercise, FFA mobilization  • Possible causes: hGH, sympathetic stimulation, catecholamines

  43. Obesity: Role of Physical Activity in Weight Control • Spot reduction a myth • Local exercise ≠ local fat loss • Exercise draws on all fat stores • Local exercise  local muscle development • Spot reduction studies • Tennis: dominant versus nondominant arms • Intense sit-up training program

  44. Obesity: Role of Physical Activity in Weight Control • Low-intensity aerobics and weight loss • High intensity   percent energy from CHO oxidation • Low intensity   percent energy from fat oxidation • Low intensity  no change in total fat kilocalories expended • Low intensity   in total kilocalories expended • Fatmax zone • Zone where fat oxidation rates near peak • 55 to 72% VO2max

  45. Table 22.5

  46. Figure 22.9

  47. Obesity: Role of Physical Activity in Weight Control • Exercise gimmicks ineffective. Examples: • Mark II Bust Developer • Astro-Trimmer Exercise Belt • Slim-Skins Vacuum Pants • Reality: exercise and weight loss require work

  48. Obesity: Physical Activity and Health Risk Reduction • Exercise   risk of disease mortality • Irrespective of weight loss • Good news for those who struggle with weight loss • Active lifestyle and fitness more important

  49. Diabetes:Terminology and Classification • Diabetes mellitus • Hyperglycemia • Insulin insufficiency and/or resistance • Type 1 • Type 2 • Gestational • Prediabetes

  50. Diabetes:Terminology and Classification • Type 1 diabetes • Autoimmune (b-cells destroyed, no insulin) • Insulin-dependent diabetes mellitus (IDDM) • 5 to 10% of all diabetes cases • Type 2 diabetes • Loss of insulin sensitivity (insulin resistance) • Non-insulin-dependent diabetes mellitus (NIDDM) • 90 to 95% of all diabetes cases • Term adult onset no longer correct

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