7: Body Weight and Body Composition Your Health Today, 6th edition

Overweight and Obesity Overweight: body weight that exceeds the recommended guidelines for good health Obesity: body weight that greatly exceeds the recommended guidelines No sex, age, state, racial group, or educational level is spared from these problems, although they are worse for the young and the poor Overweight and obesity are associated with serious health problems

What Is a Healthy Body Weight? There is no ideal body weight for each person, but there are ranges for a healthy body weight A healthy body weight is defined as: Acceptable Body Mass Index (BMI) Body composition with an acceptable amount of body fat Fat distribution that is not a risk factor for illness Absence of any medical conditions that would suggest the need for weight loss

Body Mass Index Body mass index (BMI) is a measure of body weight in relation to height See Table 7.1 There appears to be a U-shaped relationship between BMI and risk of death, with the lowest risk in the 18.5 to 25 range Underweight: BMI less than 18.5 Healthy weight: BMI between 18.5 and 24.9 Overweight: BMI between 25 and 29.9 Obese: BMI of 30 or greater

Body Mass Index (2) BMI may incorrectly estimate risk for some people For those with muscular build, BMI may overestimate body fat For the elderly or others with low muscle mass, BMI may underestimate body fat

Body Fat Percentage Different groups have different body fat expectations Healthy range for a typical male is 8–24%; male athletes, 5–10% Healthy range for a typical female is 21–35%; female athletes, 15–20% Below a certain body fat threshold, hormones cannot be produced and health problems can occur Body fat percentage can be measured by: Immersion (most accurate), X-ray, skinfold measurement, and bioelectrical impedance

Body Fat Distribution Where you carry your body fat is important in determining your health risk A large abdominal circumference is associated with high cholesterol levels and higher risk for heart disease, stroke, diabetes, and hypertension Obese men tend to accumulate abdominal fat Obese women tend to accumulate hip and thigh fat; however, the onset of menopause shifts weight gain to the abdomen If your BMI is in the healthy range, a large waist may signify an independent risk for disease

Issues Related to Overweight and Obesity Obese people are four times more likely to die before their expected lifespan and have increased risk for: High blood pressure Diabetes Elevated cholesterol levels Coronary heart disease Stroke Gallbladder disease Osteoarthritis Sleep apnea Lung problems Certain cancers, such as uterine, prostate, and colorectal

Diabetes and Obesity The rates of obesity and diabetes in the U.S. have risen in parallel About 90–95% of people with diabetes have Type-2, the form strongly associated with obesity About 80% of American youth with Type-2 diabetes are obese At any age group, small reductions in weight through diet and exercise reduce the risk of developing diabetes

Discrimination and Obesity Overweight children are often teased or bullied Weight-related bullying does not stop with adulthood The overweight face discrimination in hiring practices, lower wages, and social stigma A study found the overall, tangible cost of obesity for a woman was $4,879 per year, and for a man, $2,646

The Problem of Underweight A sudden, unintentional weight loss without a change in diet or exercise level may signify an underlying illness and should prompt a visit to a physician If you have difficulty keeping weight on, to gain weight you need to change your energy balance Eat more frequent and energy-dense meals Add nutritional supplements as snacks Reduce aerobic exercise and increase resistance or weight training

What Factors Influence Your Weight? Many factors contribute to this trend, both individual and environmental For most people, obesity is a multifactorial condition: a person’s susceptibility is due to a complex interaction among multiple genes and his or her environment

Genetic and Hormonal Influences Your risk of becoming obese if both your parents are obese is 80 percent Hundreds of genes have been associated with BMI and obesity In most cases, multiple genes may predispose toward obesity, but interactions with the environment determine outcome Genetic affects on hormone levels result in alterations in appetite or energy expenditure

Genetic and Hormonal Influences (2) Stress response also affects eating patterns The body releases several hormones, and in response, fat cells release fatty acids and triglycerides and increase circulating glucose When stress is chronic, the constant presence of these hormones increases the amount of fat deposited in the abdomen Stress also affects eating patterns

Genetic and Hormonal Influences (3) Thyroid disorders can be associated with weight gain or weight loss Thyroid gland controls much of your metabolic rate through hormone production When it is overactive, weight loss will likely result When it is not active enough, weight gain will likely result

Age and Gender Poor childhood eating habits are believed to be a major cause of the recent surge in overweight and obesity Healthy body fat percentage changes as we age Children, 12% Male adults, 15%; female adults, up to 25% Between the ages of 20 and 40, both men and women gain weight Older adults are susceptible to weight gain and need to be attentive to their lifestyle in order to maintain a healthy weight

Obesogenic Environments and Lifestyle Our chances of becoming obese are significantly influenced by our environment Choice in food is driven by exposure, as well as cost and convenience In general, unhealthy foods are more convenient and less expensive than healthy foods Eating out has become a part of daily life These foods tend to be higher in fat and calories and lower in fiber than a home-cooked meal When confronted with large serving sizes, people eat more and don’t realize it

Obesogenic Environments and Lifestyle (2) Our car-friendly, pedestrian-unfriendly communities mean people are less likely to walk Americans spend much of their leisure time on sedentary entertainments like TV and the Internet Less sleep, not more, is associated with weight gain in young adults If your friends gain weight, you are more likely to gain weight Weight cycling—repeated cycles of weight loss and weight gain as a result of dieting—contributes

The Key to Weight Control: Energy Balance Energy balance: the relationship between caloric intake (in the form of food) and caloric output (in the form of metabolism and activity) If you take in more calories than you use through metabolism and movement (positive energy balance), you store these extra calories as body fat If you take in fewer calories than you need (negative energy balance), you draw on body fat stores to provide energy

Estimating Your Daily Energy Requirements You can estimate your daily energy expenditure by considering the: Thermic effect of food Energy spent on basal metabolic rate, and Energy spent on physical activities

Estimating Your Daily Energy Requirements (2) Thermic effect of food: an estimate of the energy required to process the food Estimated at 10% of energy intake Basal metabolic rate (BMR): rate at which the body uses energy to maintain basic life functions, such as digestion, respiration, and temperature regulation About 60–70% of energy consumed Between 10% and 30% of the calories consumed each day are used for physical activity

Adjusting Your Caloric Intake Reasonable weight loss of 1 pound to 2 pounds per week is a healthy goal A pound of body fat stores 3,500 calories To lose 1 pound in a week, you need to decrease your total intake for the week by that 3,500 calories Faster weight loss tends to include loss of lean tissue and a decrease in your basal metabolic rate Foods high in complex carbohydrates have a greater thermic effect and take more energy to process than high-fat foods

Fad Diets Popular fad diets promote rapid change but are not associated with long-term weight loss Most follow a pattern of altering the balance of carbohydrates, protein, and fat Many label certain foods as “good” or “bad” or prescribe certain “fat-burning foods” Most dietitians and physicians encourage more balanced options and self-monitoring concepts

Weight Management Organizations Weight management organizations offer group support, nutrition education, dietary advice, exercise counseling, and other services Weight Watchers: a commercial program Take Off Pounds Sensibly (TOPS): a free program providing group support; focuses on teaching Overeaters Anonymous: a free program providing group support; more suitable for binge eaters or others with emotional issues related to weight

The Medical Approach Very-low-calorie diets Prescription drugs An aggressive option that requires a physician’s supervision Maintaining weigh loss is challenging Prescription drugs Two types: those that act in brain to reduce food intake and those that act elsewhere in the body to reduce food absorption Side effects are an issue

The Medical Approach (2) Surgical options Gastric surgery is never a first-line approach Typical weight loss ranges from 20% to 30% of weight Nonprescription diet drugs and dietary supplements Diet teas, bulking products, starch blockers, diet candies, sugar blockers, benzocaine, etc. There are many safety concerns Manufacturers of dietary supplements do not have to submit proof of their efficacy or safety to the FDA

The Size Acceptance Movement Seeks to decrease negative body image, encourage self-acceptance, and end discrimination Emphasizes that people of any size can become more fit and benefit from healthier food choices The goal is to find a balanced approach that combines personal acceptance with promotion of a healthy body composition

Tasks for Individuals Emphasize components of a healthier lifestyle A balanced diet emphasizing fruits, vegetables, and whole grains in appropriate portion sizes 150 minutes weekly of moderate-intensity physical activity Reduced time spent in sedentary activities Target improvement in areas such as blood pressure, cholesterol, and blood sugar level Inclusion of peer support Self-acceptance of body size Follow-up evaluation by a health professional

Tasks for Individuals (2) Set SMART goals SMART: Specific, Measurable, Attainable, Realistic, Timely Is the goal specific? Is the goal measurable? Is the goal attainable, through action on your part? Is the goal realistic, using small, gradual changes? Is the goal timely, in that you set a time line for when you will reach it?

Tasks for Individuals (3) Choose an appropriate diet approach, based on specific goals Lose or gain a small amount of weight Maintain weight loss long-term Replace unhealthy eating and exercise behaviors with more healthy behaviors Reduce risk or controlling symptoms of diabetes (including maintainable short-term weight loss) Improve heart health

Table 7.2 Dieting Approaches Type Theory Examples Balanced diets (for diabetes and heart heath as well as weight loss) Encourage some restriction of total calorie intake and focus on lower carbohydrates and lower fats. They tend toward balance among food groups. DASH, Dr. Weil’s Anti-inflammatory, flexitarian, Jenny Craig, Mediterranean, Mayo Clinic, traditional Asian, Volumetrics, Weight Watchers, Zone Commercial diet programs Typically based on changing food patterns and increasing exercise, with the help of behavioral counseling and support systems. Jenny Craig, Nutrisystem, Weight Watchers Low-calorie diets (includes most weight-management organizations) Specifically incorporate reduction in overall calorie intake. Body Reset, HMR, Jenny Craig, Nutrisystem, raw food, Weight Watchers

Table 7.2 Dieting Approaches (Continued) Type Theory Examples Food-group-restrictive diets Certain types of food classified as “bad” are eliminated; other foods are “good” metabolic promoters. Low-fat: macrobiotic, Ornish, TLC, vegetarian, vegan. Low-carb/high-protein: Atkins, Paleo, South Beach. Detox: Master Cleans (aka Lemonade Diet) Meal replacements (shakes and bars) Prepacked bars and drinks are used to control calorie intake. Body Reset, HMR, Medifast, Slim-Fast Prepackaged meals Purchased meals are used to control calorie intake. HMR, Jenny Craig, Nutrisystem, Weight Watchers

Tasks for Individuals (4) Evaluate the support and obstacles in your environment, asking yourself if your change in diet is: Realistic Moderate and flexible Safe Holistic, incorporating regular exercise Compatible with your relationships Affordable Research-based

Tasks for Individuals (5) Use tools to help change your patterns Stimulus control: identify environmental cues associated with unhealthy eating habits Self-supervision: keep a log of the food you eat and the physical activity you do Social support and positive reinforcement: recruit others to join you in your healthier habits Stress management: use healthy techniques and problem-solving strategies to handle stress Cognitive restructuring: moderate any self-defeating thoughts and emotions; redefine your body image by thinking about what your body can do

Tasks for Society Changes in social policies are also needed to combat the obesity epidemic Promote healthy foods, lowering the price of low-fat, nutritious food to increase the rates at which people choose them Support active lifestyles through community planning Support consumer awareness If consumers don’t buy the products depicted in ads, or if they complain about the content of ads, food manufacturers will eventually respond Encourage health insurers to cover obesity prevention programs

In Review How is healthy body weight defined? What factors influence weight? What is the best way to manage body weight? Are there quick fixes for overweight and obesity? How can individuals and society promote healthy weight throughout life?