Achieving and Maintaining a Healthful Body Weight

1. 13 Achieving and Maintaining a Healthful Body Weight

2. What Is a Healthful Body Weight? • Appropriate for age, physical development • Maintained without constant dieting • Based on genetic background and family history of body shape and weight • Compatible with normal blood pressure, lipid levels, and glucose tolerance • Promotes good eating habits and allows for regular physical activity • Acceptable to you

3. What Is a Healthful Body Weight? • Underweight: having too little body fat to maintain health • Overweight: having a moderate amount of excess body fat

4. What Is a Healthful Body Weight? • Obese: having an excess of body fat that adversely affects health • Morbid obesity: body weight exceeding 100% of normal, a very high risk for serious health consequences

5. Evaluating Body Weight • Determining if a person’s body weight is healthful should include: • Determining the body mass index (BMI) • Measuring body composition • Assessing the pattern of fat distribution

6. Body Mass Index • Expresses the ratio of a person’s weight to the square of his or her height • BMI = weight (kg)/height (m)2 • BMI = [weight (lbs)/height (inches)2] × 703 • BMI values below 18.5 or above 30 have increased health risks • Not an indication of body composition

9. Fat Distribution Pattern • Apple-shaped fat patterning—upper body • Increased risk for chronic diseases • Men tend to store fat in the abdominal region • Pear-shaped fat patterning—lower body • No significant increased chronic disease risk • Women tend to store fat in the lower body

11. Fat Distribution Pattern • Abdominal fat increases risk for chronic disease • Waist-to-hip ratio • Men: waist-to-hip ratio higher than 0.90 • Women: waist-to-hip ratio higher than 0.80 • Waist circumference • Men: above 40 in. (or 102 cm) • Women: above 35 in. (or 88 cm)

13. Body Composition • Measure body fat and lean body mass by • Underwater weighing • Skinfold measurements • Bioelectric impedance analysis • Near-infrared reactance • Dual-energy x-ray absorptiometry (DXA) • Bod Pod™

16. Gaining or Losing Weight • Weight gain or loss depends on • Energy intake vs. energy expenditure • Genetic factors • Childhood weight • Behavioral factors • Social factors

17. Energy Balance • Energy balance equation • Energy intake = energy expenditure • Energy intake is kcal from food, beverages • Energy expenditure is energy expended at rest and during physical activity

19. Energy Intake • Calculating the energy that is in a particular food • Carbohydrate is 4 kcal/g • Protein is 4 kcal/g • Fat is 9 kcal/g • Alcohol is 7 kcal/g • 1 cup of quick oatmeal has 142 kcal • 6 grams protein × 4 kcal/gram = 24 kcal • 25 grams carbohydrate × 4 kcal/gm = 100 kcal • 2 grams fat × 9 kcal/gram = 18 kcal • Total kcal = 24 kcal + 100 kcal + 18 kcal = 142 kcal

20. Energy Intake • When total daily energy intake exceeds the amount of energy expended, weight gain results • An excess intake of approximately 3,500 kcal will result in a gain of 1 pound • Without exercise, this gain will likely be fat

21. Energy Expenditure • Energy is expended to maintain basic body functions and to perform activities • Total 24-hour energy expenditure is composed of three components: • Basal metabolic rate (BMR) • Thermic effect of food (TEF) • Energy cost of physical activity

23. Energy Expenditure • Direct calorimetry is a method that measures the amount of heat the body releases • Indirect calorimetry estimates energy expenditure by measuring oxygen consumption and carbon dioxide production

25. Basal Metabolic Rate (BMR) • Energy expended to maintain basal (resting) functions of the body • Includes respiration, circulation, maintaining body temperature, new cell synthesis, secretion of hormones, and nervous system activity • Primary determinant of BMR is the amount of lean body mass

28. Energy Expenditure • Thermic effect of food (TEF) • Energy expended to process food • About 5−10% of the energy content of a meal • Energy cost of physical activity • About 15−35% of total daily energy output

30. Genetic Factors • Influence height, weight, body shape, metabolic rate • About 25% of one’s body fat is accounted for by genetic influences • Different ideas have been suggested to explain the impact of genetics on body fat • Thrifty gene theory • Set-point theory

32. Thrifty Gene Theory • Proposes that a gene (or genes) causes people to be energetically thrifty • People with this gene expend less energy than other people • Protects from starvation during times of extreme food shortages • A “thrifty gene” has not been identified

33. Set-Point Theory • Suggests that body weight stays within a narrow range (set point) • Compensates for changes in energy balance and keeps a person’s weight at his or her set point

34. Composition of the Diet • Theory states that overeating dietary fat promotes storage as adipose tissue • Overeating carbohydrate or protein: • Used for energy, storage, or tissue building • Smaller amount of the excess stored as fat • Also leads to weight gain • Important to maintain a balanced diet combining fat, carbohydrate, and protein Reading Labels

35. Physiologic Factors • Hunger and satiety • Proteins affect the regulation of appetite and storage of body fat • Leptin acts to reduce food intake • Ghrelin stimulates appetite • Peptide YY (PYY) decreases appetite • Uncoupling proteinsin brown adipose tissue increase energy expenditure

36. Physiologic Factors • Increase satiety (or decrease food intake) • Hormones—serotonin, cholecystokinin (CCK) • Increase in blood glucose levels after meal • Stomach expansion • Nutrient absorption from the small intestine • Decrease satiety (or increase food intake) • Hormones—beta-endorphins • Neuropeptide Y • Decreased blood glucose levels

37. Cultural and Economic Factors • Religious beliefs • Learned food preferences • Fast-food culture • Sedentary lifestyle • Economic status • Access to healthcare

38. Psychologic and Social Factors • Appetite: psychological drive to eat • Meal timing and size: portion distortion • Sight and fragrance of foods • Mood, depression • Barriers to physical activity • Technological lifestyle • Social pressures

39. Achieve and Maintain Healthful Weight • Healthful weight change requires • Gradual change in energy intake • Regular and appropriate physical activity • Behavior modification techniques • Tips • Avoid fad diets • Achieve negative energy balance ABC Video Fad Diets

41. Weight-Loss Diets • Moderate-fat, high-carbohydrate, moderate-protein diets • Balanced in nutrients: 20−30% calories from fat, 55−60% from carbohydrate, 15−20% from protein • Weight Watchers, Jenny Craig, DASH diet, and the USDA MyPyramid • Gradual weight loss (1−2 pounds per week) • Typical energy deficits = 500−1,000 kcal per day

42. Weight-Loss Diets • High-fat, low-carbohydrate, high-protein diets • 55–65% of total energy intake as fat and less than 100 g of carbohydrate per day • Dr. Atkins’ Diet Revolution, Protein Power • Cause ketosis, which will decrease blood glucose and insulin levels and reduce appetite • Concerns about long-term compliance, potential health risks, and side effects

43. Weight-Loss Diets • Low-fat and very-low-fat diets • About 11−19% of total energy as fat, while very-low-fat-diets contain less than 10% • Dr. Dean Ornish’s Program for Reversing Heart Disease and The New Pritikin Program • Emphasize complex carbohydrates and fiber • Regular physical activity is a key component • Lower LDL cholesterol, triglyceride, glucose, and insulin levels, and lower blood pressure

44. Achieve and Maintain Healthful Weight • Set realistic and achievable goals that are: • Specific • Reasonable • Measurable ABC Video Crash Diet ABC Video Meal Replacements

45. Achieve and Maintain Healthful Weight • Follow recommended serving sizes • Reduce high-fat and high-energy food intake • Consume foods that are relatively low in energy density • Participate in regular physical activity • Incorporate appropriate behavior modifications into daily life

47. Weight-Loss Medications • Used only with a physician’s supervision • Long-term safety and efficacy explored • Sibutramine (Meridia): reduces appetite • Orlistat (Xenical): inhibits fat absorption • Should only be used if a person has • A BMI of 30 kg/m2 • A BMI of 27 kg/m2 and other health risk factors

48. Dietary Supplements • Dangerous or ineffective supplements can be marketed and sold without meeting the FDA’s strict safety and quality standards • Insufficient evidence to support their use • Stimulants speed up metabolic processes; are controversial; and may be dangerous • Caffeine, phenylpropanolamine (PPA), and ephedra

49. Safe and Effective Weight Gain • Underweight: BMI of less than 18.5 kg/m2 • Limit fat: <30% of total energy intake • Eat 500 to 1,000 extra kcal/day • Eat frequently throughout the day • Avoid tobacco (depresses appetite and increases BMR) • Exercise regularly with resistance training

50. Protein Supplements • Include amino acid supplements, anabolic steroids, and androstenedione • Do not enhance muscle gain or result in improvements in strength • Cause major health problems: unhealthful changes in blood cholesterol, mood disturbances