© 2011 Pearson Education, Inc. 13 Achieving and Maintaining a Healthful Body Weight

© 2011 Pearson Education, Inc. 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

© 2011 Pearson Education, Inc. What Is a Healthful Body Weight? Underweight: having too little body fat to maintain health Overweight: having a moderate amount of excess body fat

© 2011 Pearson Education, Inc. 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

© 2011 Pearson Education, Inc. 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

© 2011 Pearson Education, Inc. 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

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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

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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)

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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™

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

© 2011 Pearson Education, Inc. 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

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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 kcal + 18 kcal = 142 kcal

© 2011 Pearson Education, Inc. 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

© 2011 Pearson Education, Inc. 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

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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

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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

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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

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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

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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

© 2011 Pearson Education, Inc. 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

© 2011 Pearson Education, Inc. 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

© 2011 Pearson Education, Inc. 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 proteins in brown adipose tissue increase energy expenditure

© 2011 Pearson Education, Inc. 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

© 2011 Pearson Education, Inc. Cultural and Economic Factors Religious beliefs Learned food preferences Fast-food culture Sedentary lifestyle Economic status Access to healthcare

© 2011 Pearson Education, Inc. 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

© 2011 Pearson Education, Inc. 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

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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

© 2011 Pearson Education, Inc. 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

© 2011 Pearson Education, Inc. 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

© 2011 Pearson Education, Inc. Achieve and Maintain Healthful Weight Set realistic and achievable goals that are: Specific Reasonable Measurable ABC Video Crash Diet ABC Video Meal Replacements

© 2011 Pearson Education, Inc. 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

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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/m 2 A BMI of 27 kg/m 2 and other health risk factors

© 2011 Pearson Education, Inc. 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

© 2011 Pearson Education, Inc. 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

© 2011 Pearson Education, Inc. 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

© 2011 Pearson Education, Inc. Overweight BMI between 25 and 29.9 kg/m 2 Health risks: high blood pressure, heart disease, type 2 diabetes, sleep disorders Many overweight people will become obese Recommend healthful eating and regular physical activity to prevent additional weight gain, achieve a healthful weight, support long- term health Increase in Obesity Rates in the United States

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Obesity and Morbid Obesity Obesity: BMI from 30 to 39.9 kg/m 2 Morbid obesity: >100% normal weight Considered an epidemic in the United States Linked to many chronic diseases: Hypertension Dyslipidemia Diabetes Heart disease Stroke

© 2011 Pearson Education, Inc. Metabolic Syndrome A cluster of factors increases risk for heart disease, type 2 diabetes, and stroke: Abdominal obesity (waist circumference >40 inches for men, 35 inches for women) Triglyceride levels (>150 mg/dL) HDL cholesterol levels (<40 mg/dL in men and 50 mg/dL in women) Blood pressure (>130/85 mm Hg) Fasting blood glucose >100 mg/dL

© 2011 Pearson Education, Inc. Obesity: Multifactorial Disease Genetic and physiologic factors Childhood obesity linked to adult obesity Critical periods might increase risk Gestation and early infancy Period of weight gain (adiposity rebound) that occurs between 5 and 7 years of age Adolescence (or puberty)

© 2011 Pearson Education, Inc. Obesity Treatment Low-calorie diet and regular exercise Prescription medications Surgery Vertical banded gastroplasty Gastric bypass surgery Gastric banding Liposuction ABC Video Gastric Bypass Surgery

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