C H A P T E R 21

1. C H A P T E R 21 OBESITY, DIABETES, AND PHYSICAL ACTIVITY

2. w Discover the prevalence of obesity in the United States and what health-related problems are associated with it. (continued) Learning Objectives w Differentiate between overweight and obesity. w Find out how ideal body weight, relative body weight, and body mass index are determined.

3. Learning Objectives w Examine the interrelationships among obesity, coronary artery disease, hypertension, and diabetes. w Learn the most effective methods for treating and preventing obesity. w Find out how exercise can result in losses in total weight and fat weight. w Review the two types of diabetes and the role exercise plays in their treatment.

4. Terminology Body mass index (BMI)—a standard to estimate obesity determined by dividing body weight in kg by the square of height in m Overweight—body weight that exceeds the normal or standard weight for a particular person based on height and frame size – BMI of 25.0-29.9 kg/m2 Obesity—the condition of having an excessive amount of body fat (more than 25% in men and more than 35% in women) – BMI of > 30 kg/m2 Relative weight—the percentage that an individual is overweight or underweight according to standard height and weight charts

5. Disease risk (relative to normal weight and waist circumference) Men ≤40 in. Men > 40 in. (102 cm) (102 cm) Women ≤35 in. Women >35 in.Classification BMI (kg/m2) Obesity class (88 cm) (88 cm) Underweight <18.5 — — Normalb 18.5-24.9 — — Overweight 25.0-29.9 Increased High Obesity 30.0-34.9 I High Very high 35.0-39.9 II Very high Very high Extreme ≥40 III Extremely high Extremely high Note. BMI = body mass index. aDisease risk for type 2 diabetes, hypertension, and cardiovascular disease. bIncreased waist circumference also can be a marker for increased risk even in persons of normal weight. Classification of Overweightness and Obesity by BMI, Waist Circumference, and Associated Disease Riska

6. Obesity and Overweightness in the U.S. w Prevalence of obesity has dramatically increased in the past 35 years. w Nearly 67% of men and 62% of women are overweight or obese. w Prevalence in children has increased markedly since 1980. w Average adult gains 0.45 kg (1 lb) per year after age 25. w Average adult loses 0.2 kg (0.5 lb) of muscle and bone mass each year after age 25.

7. PREVALENCE OF OVERWEIGHTNESS IN U.S.

8. PREVALENCE OF OBESITY IN U.S.

9. PREVALENCE OF OVERWEIGHTNESS AND OBESITY IN U.S.

10. PREVALENCE OF OVERWEIGHTNESS AND OBESITY IN MEN IN U.S. BY RACE

11. PREVALENCE OF OVERWEIGHTNESS AND OBESITY IN WOMEN IN U.S. BY RACE

12. PREVALENCE OF OVERWEIGHTNESS IN CHILDREN

13. Resting metabolic rate (RMR) w Rate measured early in the morning after an overnight fast and 8 hours of sleep. w 60% to 75% of daily energy used Thermic effect of a meal (TEM) w Energy used for digestion, transport, and metabolism of ingested food w 10% of daily energy used Thermic effect of activity (TEA) w Energy above RMR needed to perform activities – most variable of the factors w 15% to 30% of daily energy used Energy Expenditure

14. DAILY ENERGY EXPENDITURE

15. American Dietary Habits Since 1970, more Americans are eating more meals outside the home (i.e., high fat, high carb, high salt), relying more heavily on convenience foods, and consuming larger food portions (i.e., supersizing). These trends point to a general increase in daily energy intake over the past 30 years.

16. w It is hypothesized that the set point can increase with an increase in fat content ingested and a decrease in physical activity. (continued) Key Points Body Weight Control w A gain of 0.7 kg (1.5 lb) per year represents an imbalance of less than 15 kcal per day (the equivalent of one potato chip). w Body weight appears to be regulated around a set point.

17. Key Points Body Weight Control w Daily energy expenditure is made up of the resting metabolic rate (RMR), the thermic effect of a meal (TEM), and the thermic effect of activity (TEA). w The body defends its weight against changes in energy intake by increasing or decreasing these components. Thus, during dieting or fasting, the body decreases its RMR.

18. Potential Causes of Obesity w Genetic predisposition w Physiological, psychological, or emotional trauma w Hormonal imbalances w Cultural or familial factors w Diet composition w Physical inactivity

19. WEIGHT GAINS BETWEEN TWINS Identical twins were overfed by 1000 kcal/day for 84 out of 100 days – data show the strong genetic component in weight gain

20. BMI FOR PIMA INDIANS These data demonstrate the strong influence of the quantity and quality of the diet in persons with similar genetic background

21. Health Risks of Overweight and Obesity w Increased overall mortality rates w Changes in normal body function such as respiratory function w Increased disease risks of CAD, hypertension, stroke, high blood lipids, and diabetes w Detrimental effects on existing heart, vascular, and metabolic diseases w Adverse psychological reactions

22. BMI AND EXCESS MORTALITY

23. Methods of Estimating Obesity w Body composition measures (e.g., underwater weighing) w Relative weight w Body mass index w Waist-to-hip ratio

24. Upper-body (android) obesity w Greater fat storage in the upper body and abdominal area (apple shaped) w Occurs more frequently in men w Carries greater risk for CAD, hypertension, stroke, and diabetes Lower-body (gynoid) obesity w Greater fat storage in the lower body around the hips, buttocks, and thighs (pear shaped) w Occurs more frequently in women Fat Distribution

25. Android and Gynoid Obesity

26. COMPUTED TOMOGRAPHY (CT) SCANS a b Method for measuring abdominal fat – these measures were made at the level of the fourth lumbar vertebra in two different people; the second (b) has much higher abdominal fat

27. Key Points Treating Obesity w Individuals respond differently to different treatments. w Weight loss should not exceed 0.45 to 0.9 kg (1 to 2 lb) per week and should be considered a long-term project. w Diets should stay balanced and meet the body's vitamin and mineral requirements. w The most effective treatments involve a permanent change in eating habits and behaviors and in physical activity levels.

28. Effects of Training on Body Composition w Increases calories used for energy wMetabolic rate remains elevated during recovery period w Increases lipid mobilization, losses of fat mass, and gains in fat-free mass – the greater the fat-free mass, the higher the RMR w Controls appetite such that intake better balances expenditure

29. Weight Loss Strategy Attempts to lose weight are most successful and long-standing if you lose no more than 0.45 to 0.9 kg (1 to 2 lb) per week and combine dietary restriction (300 to 500 kcal per day) with moderate aerobic and resistance exercise.

30. Energy-Balance Equation No body weight is gained or lost (excluding temporary changes in water) when the two sides of the energy-balance equation are equal; if the left side of the equation is greater, weight is gained; if the right side is greater, weight is lost: Energy intake − energy excreted = RMR + TEM + TEA

31. BODY CHANGES, DIET, AND EXERCISE Adult women maintained a total caloric deficit of 500 kcal/day for 16 weeks

32. Spot Reducing? Exercise, even when localized (e.g., ab crunches), draws from fat stores throughout the body; thus, there is no such thing as spot reduction. Low-intensity aerobics burn no more fat than more vigorous exercise, and more total calories are spent with higher-intensity exercise when a given amount of time can be devoted to exercise.

33. Estimation of Kilocalories Used From Fat and Carbohydrate for a Low- and High-Intensity Aerobic Training Bout in a Fit, But Not Highly Trained 23-Year-Old Woman (VO2max = 3.0 L/min) . Average kcal for kcal for kcal forExercise VO2 Average %kcal %kcal 30 min 30 min 30 minintensity (L/min) RER CHO fat CHO fat total . Low, 50% 1.50 0.85 50 50 110 110 220 High, 75% 2.25 0.90 67 33 222 110 332 Note. RER = respiratory exchange ratio; CHO = carbohydrae.

34. RATE OF FAT OXIDATION

35. What Role Does Exercise Play in Weight Loss? w Exercise alone does not lead to major changes in mass or body composition. From three major reviews, exercising for 6 months should decrease body mass by 3.5 lb, fat mass by 5.7 lbs, and relative fat by 3% (e.g., 30% to 27%) and increase fat-free mass by 2.2 lbs. w These changes are similar to those seen with diet, drugs, and behavior modification—disappointing! w Exercise likely plays its major role in preventing future weight gain, so the earlier we start the better. Also, in combination with diet, it facilitates loss of fat mass without loss in fat-free mass.

36. Diabetes Mellitus (Greek: a Flow-Through of Honey) w Disorder of carbohydrate metabolism characterized by high blood sugar levels and presence of sugar in the urine w Affects approximately 16 million Americans w Develops when insulin production is inadequate or when insulin is ineffective in facilitating the transport of glucose from blood into cells w Most cases are classified as type 1 or type 2 w Prevalence increases with aging; affects 25% of adults over 85 years of age

37. Type 1 Diabetes w Insulin-dependent (IDDM) w Onset occurs most often during childhood or young adulthood w Requires daily injections of insulin • Includes only 5% to 10% of all individuals with diabetes • Excessive hunger, thirst, urination and loss of weight

38. Type 2 Diabetes w Non-insulin dependent in the early stages (NIDDM) w Onset occurs most often gradually during adulthood (now being seen in more and more children) w Includes 90% to 95% of all individuals with diabetes

39. Type 1 w Heredity w Destruction of insulin-secreting beta cells in the pancreas w Destruction possibly linked to immune system dysfunction Type 2 w Heredity w Impaired insulin action (insulin resistance); later, impaired insulin release as beta cells “fatigue” w Excessive glucose output from the liver w Beta-cells become less responsive to increased blood glucose–obesity-related w Target cells undergo reduction in active insulin receptors–obesity-related Causes of Diabetes Mellitus

40. Health Problems and Diabetes w Coronary artery and peripheral vascular disease (increased atherosclerosis; ulceration, gangrene) w Cerebrovascular disease and stroke (atherosclerosis) w Hypertension w Toxemia during pregnancy w Renal disorders (diabetic nephropathy) w Eye disorders (diabetic retinopathy)

41. Treating Diabetes w Individualized insulin administration and monitoring (if needed) for type 1 diabetes w Well-balanced diet w Regular exercise and physical training w Weight loss and maintenance of healthy weight

42. Key Points Physical Activity and Diabetes w People with type 1 diabetes may or may not improve their glycemic control with exercise, but exercise will help lower their risk for coronary artery disease. w It is important to carefully monitor blood sugar levels of individuals with type 1 diabetes during exercise so that diet and insulin dosage can be altered as needed. w Attention to foot care is especially important for individuals with type 1 diabetes due to decreased sensation and peripheral blood flow in the feet. w Exercise increases muscle and fat cell uptake of glucose, which decreases insulin resistance and increases insulin sensitivity.