Chapter 10

1. Chapter 10 Weight Management

2. Ask Yourself True of False? The less you weigh, the better it is for your health. Obese people pay higher insurance premiums than thin people. If you weigh too much according to the scales and the so-called ideal weight tables, you are too fat. If you are too fat, it is because you eat too much. Basal metabolism contributes only a small percentage of a person’s daily energy output.

3. Ask Yourself Probably the most important contributor to the obesity problem in our country is under activity. Any food can make you fat, even carrot sticks, if you eat enough of it. You can lose weight faster on a properly designed diet and exercise program than on a total fast. Fad diets are popular because their followers achieve quick and permanent weight loss. Anorexia nervosa is a disease in which a person has no appetite.

4. A Closer Look at Obesity Trends in Prevalence of Overweight and Obesity among Children and Adults, United States, 1988–2008

5. A Closer Look at Obesity • An “escalating” epidemic and one of the greatest neglected public health problems of our time (WHO) • Many factors including genetics influence body weight. • Excess energy intake and physical inactivity are the leading causes of overweight and obesity. • They also represent the best opportunities for prevention and treatment.

6. Trends resulting in poor nutrition and decreased activity: Food portion sizes and obesity rates have grown in parallel. Vending machines selling soft drinks, high-fat snacks, and sweet snacks are common in schools and workplaces. Adults spend more time in sedentary activities, such as watching television, computing, or commuting. Children watch 12 to 14 hours of television a week and spend 7 hours playing video games. Schools offer fewer physical education classes for children. Increasing numbers of families live in communities designed for car use, unsuitable and often unsafe for activities such as walking, biking, and running.

7. A Closer Look at Obesity Overweight: Conventionally defined as weight between 10% and 20% above the desirable weight for height, or a body mass index (BMI) of 25.0 through 29.9. Obesity: Conventionally defined as weight 20% or more above the desirable weight for height, or a BMI of 30 or greater. Fact: Obesity rates are higher than ever. Currently, 67% of adults and approximately 17% of children and adolescents in the U.S. are either overweight or obese—exceeding their healthy weight range. Annual cost of overweight and obesity exceeds $117 billion a year. Direct costs (treatment) Indirect costs (lost productivity, disability, morbidity & mortality)

8. The Epidemic of Obesity among U.S. Adults

10. Problems Associated with Weight Some people can weigh too much while others weigh too little. Underweight: Weight 10% or more below the desirable weight for height, or a BMI less than 18.5. Problems of underweight individuals: Possess minimal fat stores. Could be at a disadvantage when energy reserves are needed. Menstrual irregularity, infertility, osteoporosis.

12. What Is a Healthy Weight? Body Weight versus Body Fat Two people of the same sex, age, and height may both weigh the same, yet one may be too fat and the other too thin. The difference lies in their body composition. Obesity must be defined by amount of body fat rather than by weight. The health risks for obesity refer to people who are overfat. Desirable measures for percent body fat: Men 12%-20% (overfat would be >25%) Women 20%-30% (overfat would be >33%)

13. What Is a Healthy Weight? Measuring Body Fat • Body fatness is hard to measure. • One very accurate way is to measure the body’s density. • Weight divided by volume • Lean tissue is more dense than fat tissue. Underwater weighing or hydrostatic weighing measures the amount of water displaced.

14. What Is a Healthy Weight? Measuring Body Fat • Body density can more easily be determined by air displacement methods. • The BodPodmeasures the volume of air displaced by a person when seated in a sealed device of known volume.

15. What Is a Healthy Weight? Measuring Body Fat • Skinfold Test: Using a caliper to measure the thickness of a fold of fat, the measurement is then applied to a standard table to give a fair approximation of total body fat. The fatfold test gives a fair approximation of body fat.

16. What Is a Healthy Weight? Measuring Body Fat • Dual energy X-ray absorptiometry (the DEXA test) can yield an accurate image of the body’s fat-free tissue and total fat content. • This test can be costly.

17. What Is a Healthy Weight? Measuring Body Fat • Bioelectrical impedance: estimation of body fat content made by measuring how quickly electrical current is conducted through the body.

18. What Is a Healthy Weight? Distribution of Fat • Central obesity: excess fat on the abdomen and around the trunk. • “Apple-shaped” body • Strong risk factor for type 2 diabetes, heart disease, hypertension, and other problems. • Peripheral obesity: excess fat on the arms, thighs, hips, and buttocks. • “Pear-shaped” body There are health implications to how body fat is distributed.

19. Weighing In for Health A person’s health risk is dependent on three factors: Body weight Amount and location of body fat Current health status Body mass index: an index of a person’s weight in relation to height that correlates with total body fat content. BMI does not account for: Location of fat in the body Muscular people with a low percentage of body fat may have a high BMI What Is a Healthy Weight?

20. Benefits of Using BMI: BMI correlates strongly with body fatness and risk of disease and death.

21. Healthy Weight

23. What Is a Healthy Weight? Waist circumference measurement provides information about the distribution of fat in the abdomen. • Disease risk rises when waist circumference exceeds: • 35 inches in women • 40 inches in men

24. Energy Balance

25. Energy Balance 1. Basal metabolism—maintaining basic physiological processes such as breathing, heartbeat, and other involuntary activities. 2. Voluntary physical activities—an amount that will vary by activity level. 3.Some used for the thermic effect of food—the energy needed to digest, absorb, and process the food you eat. How the Body Expends Energy

26. Energy Balance • Basal metabolism: The sum total of all the chemical activities of the cells necessary to sustain life, exclusive of voluntary activities—that is, the ongoing activities of the cells when the body is at rest. • Basal metabolic rate (BMR): The rate at which the body spends energy to support its basal metabolism. The BMR accounts for the largest component of a person’s daily energy (calorie) needs.

27. Energy Balance • To increase your metabolic rate, make exercise a daily habit. • Body composition influences metabolic rate. • Weight training can help shift your body composition toward more lean tissue, thereby speeding up your metabolism.

28. Quick method for calculating your basal energy output: Men: kg of body weight × 24 = calories/day Women: kg of body weight × 23 = calories/day Note: To convert pounds to kilograms (kg), divide pounds by 2.2. For example, 150 lb = 68 kg [150 ÷ 2.2 = 68]

29. Causes of Obesity A Closer Look at Eating Behavior Hunger: The physiological drive to find and eat food, experienced as an unpleasant sensation. Appetite: The psychological desire to find and eat food, experienced as a pleasant sensation, often in the absence of hunger. Satiety: The feeling of fullness or satisfaction that people feel following a meal.

30. Causes of Obesity • Hypothalamus A part of the brain that senses a variety of conditions in the blood, such as temperature, salt content, and glucose content, and then signals other parts of the brain or body to change those conditions when necessary. • Arousal As used in this context, heightened activity of certain brain centers associated with excitement and anxiety.

31. Brain Thalamus Brain stem Hypothalamus Spinal cord

32. Causes of Obesity Eating behaviors many be a response to hunger, appetite, and other complex human sensations. Stress may also promote the accumulation of body fat. Probably the most important contributor to obesity is underactivity.

33. Weight Gain and Loss • Changes in body weight can reflect shifts in fat, fluid, bone minerals, and lean tissues (e.g. muscles). • Most quick weight-loss diets promote large losses of fluid with little or no real loss of body fat.

34. Weight Gain and Loss Weight Gain When you eat more calories than you need, where does this excess go in your body? The energy nutrients… Carbohydrate Fat Protein …contribute to body stores

35. A. When a person overeats (feasting): Food component: is broken down in the body to: and then stored as: Liver and muscle glycogen stores Glucose Carbohydrate Fatty acids Fat Body fat stores Fat after losing nitrogen in urine Amino acids Protein (first used to replace body proteins)

36. B. When a person draws on stores (fasting): Storage compound: is broken down in the body to: and then used for: Liver and muscle glycogen stores Glucose Energy Fatty acids Body fat stores

37. C. If the fast continues beyond glycogen depletion: Body component: is broken down in the body to: and then used for: Amino acids Body protein Glucose Lose nitrogen in urine Energy Ketone bodies Fatty acids Body fat

38. Ketosis an adaptation of the body to prolonged (several days’) fasting or carbohydrate restriction. Body fat is converted to ketones, which can be used as fuel for some brain cells. Weight Gain and Loss

39. Weight Gain and Loss Ketosis May be harmful by upsetting the acid-base balance of the blood. The body’s lean tissue continues to be lost at a rapid rate. The body becomes conservative and slows the process of metabolism. Requires even fewer calories

40. Diet Confusion: Weighing the Evidence • Dieting is big business in the United States. • Diets work because people limit their food consumption. • Although most diets can provide a weight loss in the short term, few people can lose weight and keep it off. • Some diets may be harmful.

41. How Can You Determine If a Diet Is Healthful? Evaluating Diets Systematically eliminates groups of foods. Probably lacking in nutrients. Hard to adhere to the eating plan. Encourages specific supplements of foods only available from selected distributor. May contain harmful or unproven ingredients. Touts magic or miracle foods that burn fat. The only way to “burn” fat is to increase physical activity or decrease the amount of calories consumed. Promotes bizarre quantities of one food or type of food. Not good advice, considering human nutritional needs.

44. Weight Gain and Loss Evaluating Diets Has a rigid menu No one diet plan will work for everyone. Promotes specific food combinations. Needlessly restricts dietary intake and choices. Promises weight loss of more than two pounds per week. A safe weight loss goal = 0.5-2.0 pounds/week. Provide warnings for people with health conditions such as diabetes and hypertension. Does the program encourage/promote physical activity?

45. Successful Weight-Loss Strategies The secret is a sensible (not to say easy) three-pronged approach involving: Healthy eating habits Exercise Behavior change Such an approach takes tremendous dedication. Many of those who complete weight-loss programs lose about 10% of their body weight, only to regain two-thirds of it back within 1 year and almost all of it back within 5 years.

46. Successful Weight-Loss Strategies Personalize Your Weight-Loss Plan Find the plan that is right for you. Think of it as an eating plan that you will adopt for life. A calorie deficit of 500 calories/day for seven days is enough to lose one pound of body fat a week. Spending an extra 250 calories per day by exercising will increase the calorie deficit.

47. Personalize Your Weight-Loss Plan • Use the 10 calorie rule: Allow 10 calories a day for each pound of your present body weight. • Put nutritional adequacy high on your list of priorities. • Include a small amount of fat in each meal • Keep concentrated sweets to a minimum • Limit alcohol to no more than 250 kcals/day

48. Successful Weight-Loss Strategies Aim for gradual weight loss. Expect to reach a plateau. Aim for a positive gain in lean body mass. Weight loss and bone health. Include adequate calcium and weight-bearing exercise. Adopt a physically active lifestyle.

49. Weight-Gain Strategies • Do exercise to build yourself up • Choose calorie-dense snacks. • Eat more frequently. • Spend more time eating each meal: Start with the calorie-dense food first, finish with dessert. • Eat regular, balanced meals. Eat more food and add extra calories.

50. The Eating Disorders Eating disorder: General term for several conditions: • Anorexia nervosa • Bulimia nervosa • Binge-eating disorder that exhibit an excessive preoccupation with: • Body weight • Fear of body fatness • Distorted body image