Copyright © 2012 Pearson Education, Inc. 11 C H A P T E R Achieving and Maintaining a Healthful Body Weight and In Depth

© 2012 Pearson Education, Inc. What Is a Healthful Body Weight? A healthful weight  Is appropriate for your age  Is maintained without constant dieting  Is acceptable to you  Is based on family history of body shape and weight  Promotes good eating habits and allows for regular physical activity

© 2012 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

© 2012 Pearson Education, Inc. What Is a Healthful Body Weight? Obesity: having an excess of body fat that adversely affects health Morbid obesity: body weight exceeding 100% of normal, creating a very high risk for serious health complications

© 2012 Pearson Education, Inc. Evaluating Body Weight A person’s actual weight is not the only factor to consider 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

© 2012 Pearson Education, Inc. Evaluating Body Weight 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 values below 18.5 or above 30 have increased risks of health problems  BMI results are distorted in people with high muscle mass (athletes and lactating women)

© 2012 Pearson Education, Inc. BMI Chart

© 2012 Pearson Education, Inc. BMI Classifications:

© 2012 Pearson Education, Inc. Body Mass Variations

© 2012 Pearson Education, Inc. Evaluating Body Weight

© 2012 Pearson Education, Inc. Evaluating Body Weight Body composition  Measurement of body fat and lean muscle mass  Can be measured by  Underwater weighing  Skinfold measurements  Bioelectrical impedance analysis  Dual-energy x-ray absorptiometry (DXA)  Bod Pod ®

© 2012 Pearson Education, Inc. Evaluating Body Weight Fat distribution pattern  Measured by waist-to-hip ratio and waist circumference  Apple-shaped fat patterning—upper body  Increased risk for chronic diseases (type 2 diabetes, heart disease, hypertension)  Pear-shaped fat patterning—lower body  No significant increased risk for chronic diseases

© 2012 Pearson Education, Inc. Evaluating Body Weight

© 2012 Pearson Education, Inc. Gaining or Losing Weight Whether a person gains or loses weight depends on  Energy intake versus energy expenditure  Genetic factors  Composition of the diet  Childhood weight  Behavioral factors  Social factors

© 2012 Pearson Education, Inc. Energy Balance Energy balance  Occurs when energy intake = energy expenditure  Energy intake = kcal from food  Energy expenditure  Energy expended at rest (basal metabolic rate)  Physical activity  Thermic effect of food

© 2012 Pearson Education, Inc. Energy Balance

© 2012 Pearson Education, Inc. Components of Energy Expenditure

© 2012 Pearson Education, Inc. Energy Balance Basal metabolic rate (BMR)  Energy expended to maintain basal, or resting, functions of the body  60–75% of total energy expenditure  More lean tissue increases your BMR  BMR decreases with age, 3–5% per decade after age 30

© 2012 Pearson Education, Inc. Energy Balance Physical activity  15–35% of daily energy expenditure  Factors that influence energy expended  The more muscle groups used, the greater the energy expenditure  Intensity  Duration  Body size

© 2012 Pearson Education, Inc. Energy Balance Thermic effect of food (TEF)  Energy expended to digest, absorb, transport, metabolize, and store food  5–10% of total expenditure  Lowest for fat and highest for protein

© 2012 Pearson Education, Inc. Composition of the Diet The thermal effect of the diet can affect energy balance  Dietary fat has minimal thermal effect  It takes more energy to digest, absorb, transport, and metabolize protein and carbohydrates; therefore, they are more energy expensive to process

© 2012 Pearson Education, Inc. Energy Balance Energy cost of physical activity  Represents about 15–35% of our total daily energy output  Is highly variable  Includes both lower-intensity and higher-intensity activities

© 2012 Pearson Education, Inc. Genetic Factors Genetic factors account for about 25% of a person’s body fat Different ideas have been suggested to explain the impact of genetics on body fat  Thrifty gene theory  Set-point theory

© 2012 Pearson Education, Inc. Factors Affecting Basal Metabolic Rate

© 2012 Pearson Education, Inc. Genetic Factors Thrifty gene theory  Proposes that a gene (or genes) causes people to be energetically thrifty  Proposes that people with this gene expend less energy than other people and therefore gain weight  A “thrifty gene” has not been identified

© 2012 Pearson Education, Inc. Genetic Factors Set-point theory  Proposes that each person’s weight stays within a small range (set point)  The body compensates for changes in energy balance and keeps a person’s weight at his or her set point  Can change with time, as diet and activity levels vary over a long period of time

© 2012 Pearson Education, Inc. Physiologic Factors  Hunger and satiety  Specific proteins and hormones  Leptin & Peptide YY or PYY: Reduces appetite  Ghrelin: Increases appetite  Brown adipose tissue  Serotonin  Cholecystokinin (CKK)

© 2012 Pearson Education, Inc. Physiologic Factors  Blood glucose levels  Stomach expansion  Nutrient absorption from the small intestine  Beta-endorphins  Neuropeptide Y

© 2012 Pearson Education, Inc. Proteins Leptin  Leptin is a hormone produced by fat cells that causes reduced food intake, reduced weight, and decreased body fat in mice  Leptin is controlled by the ob gene  Mutation of the ob gene in mice causes reduced levels of leptin, leading to increased food intake and reduced energy output  The role of leptin in human obesity is being studied

© 2012 Pearson Education, Inc. Proteins Ghrelin  Protein synthesized in the stomach  Stimulates appetite by acting on the hypothalamus Peptide YY  Produced in the GI tract  Decreases appetite  Obese people have lower levels when fasting

© 2012 Pearson Education, Inc. Behavioral Factors Food choices  The composition of a person’s diet should remain balanced Hunger versus appetite  Hunger: physiologic drive or need to eat  Appetite: a psychological desire to eat, often in the absence of hunger

© 2012 Pearson Education, Inc. Cultural and Economic Factors  Cultural customs  Changes in work and leisure activity levels  Larger body size acceptance/cultural norms  Lack of access to healthcare and health information  Lack of access to affordable, healthful foods  Lack of access to positive role models  Personal safety issues  Transportation issues

© 2012 Pearson Education, Inc. Psychological and Social Factors Psychosocial factors influencing our diet include  Family or cultural traditions  Promotion of overeating  Holidays and celebrations  Easy access to high-fat foods  Less physically active lifestyles  Societal expectations of the “perfect” body

© 2012 Pearson Education, Inc. Hot Dogs, Apple Pie, and Weight Americans spend $60 billion annually on weight- loss, but are gaining weight rather than losing it Only 5-10% of people who lose weight keep it off

© 2012 Pearson Education, Inc. The Business of Weight Loss More than 29,000 weight- loss products and services are available Almost none of them work

© 2012 Pearson Education, Inc. Lack of Consumer Protection No laws require a weight-loss product must be effective in order to be sold Weight-loss products are not tested for safety before they reach the market – some cause serious problems, even death

© 2012 Pearson Education, Inc. Weight Loss vs Weight Control Diets and weight loss do not cure overweight  People return to old habits, regain weight Improved and enjoyable eating and exercise habits are needed to keep excess weight off

© 2012 Pearson Education, Inc. Weight Loss vs Weight Control Diets and weight loss do not cure overweight  People return to old habits, regain weight Improved and enjoyable eating and exercise habits are needed to keep excess weight off

© 2012 Pearson Education, Inc. Fad Diets

© 2012 Pearson Education, Inc. Weight Regain With Popular Diets People can ’ t stick to difficult or unpleasant popular diets long – then weight is regained KNOW THIS: The best way to sustain weight loss is by making small, easy changes to diet and physical activities

© 2012 Pearson Education, Inc. Achieve and Maintain Healthful Weight Healthful weight change requires  Gradual change in energy intake  Regular and appropriate physical exercise  Application of behavior modification techniques

© 2012 Pearson Education, Inc. Achieve and Maintain Healthful Weight Effective weight loss should include  Following recommended serving sizes  Reduced intake of high-fat and high-energy foods  Regular physical exercise  To increase energy expenditure  To increase BMR

© 2012 Pearson Education, Inc. Achieve and Maintain Healthful Weight Diet plans to avoid  Fad diets—they do not result in long-term healthful weight change  Promoters claim the program is based on some new discovery  Rapid weight loss (>2 lbs/wk) with no exercise  Special foods only available from promoter  Rigid and limited menu  Diets that over- or underemphasize specific, narrowly defined nutrients as the key to weight loss

© 2012 Pearson Education, Inc. Weight-Loss Strategies Guidelines for successful weight loss 1. Set realistic goals  Specific  Reasonable  Measurable  Monitor progress regularly

© 2012 Pearson Education, Inc. Weight-Loss Strategies 2. Eat smaller portions of lower-fat foods  Follow serving sizes in MyPyramid  Reduce consumption of high-fat and high-energy foods  Consume foods low in energy density 3. Participate in regular physical activity  Critical for long-term maintenance of weight loss

© 2012 Pearson Education, Inc. Behavior Modification Successful weight loss requires behavior modification  Eat only at set times in one location  Keep a log of food consumed  Avoid buying problem foods  Serve food on smaller dishes  Eat small, regular meals throughout the day  Chew slowly and stop eating when you feel full  Share food with others  Do not purchase foods from vending machines

© 2012 Pearson Education, Inc. Successful Weight Loss

© 2012 Pearson Education, Inc. Gradual Weight Loss

© 2012 Pearson Education, Inc. Underweight  BMI below 18.5 kg/m 2  Increases the risk of infections and illness and can even be fatal  Can be just as unhealthy as overweight

© 2012 Pearson Education, Inc. Food is medicine

© 2012 Pearson Education, Inc. Achieve and Maintain Healthful Weight Effective weight gain should include  Eating 500 to 1,000 extra kcal/day  Eating frequently throughout the day  Maintaining a balanced diet, limiting fat intake to 15–30% of total energy intake  Avoiding tobacco products, which depress appetite and increase BMR  Regular exercise with resistance training

© 2012 Pearson Education, Inc. In Depth: Obesity Chronic diseases linked to obesity include  Hypertension  High cholesterol, triglycerides, and LDL-cholesterol  Type-2 diabetes  Heart disease

© 2012 Pearson Education, Inc. In Depth: Obesity Chronic diseases linked to obesity include  Stroke  Gallbladder disease  Certain cancers  Depression  Cognitive decline Obesity Rates PLAY

© 2012 Pearson Education, Inc. In Depth: Obesity Obesity and morbid obesity  Obesity: BMI from 30 to 39.9 kg/m 2  Morbid obesity: weight that exceeds 100% of normal  Five of the nine leading causes of death in the United States are associated with obesity  A multifactorial disease—many things cause obesity  Metabolic syndrome—a cluster of risk factors

© 2012 Pearson Education, Inc. In Depth: Obesity Factors that can influence the chance of developing obesity include  Genetics  Physiology  Overweight and obesity in childhood  Social factors  Physical factors such as thyroid levels, or use of certain prescription medications

© 2012 Pearson Education, Inc. In Depth: Obesity Treatments for obesity may include  Low-calorie diet and regular exercise  Lifestyle changes  Prescription medications (for some)  Surgery  Gastroplasty  Gastric bypass  Gastric banding

© 2012 Pearson Education, Inc. In Depth: Obesity

© 2012 Pearson Education, Inc. ABC News Nutrition Video Diet Dream Drug: Hope or Hype: Pros and Cons of Alli

© 2012 Pearson Education, Inc. ABC News Nutrition Video Can You Be Slim and Obese? Hidden Risk of Normal Weight Obesity

© 2012 Pearson Education, Inc. ABC News Nutrition Video Calorie Count: Eat by the Numbers

© 2012 Pearson Education, Inc. ABC News Nutrition Video Low-Cost, High-Impact Solutions