Body Composition • Body composition involves all components of the body including: • Fat mass • Muscle mass • Bone mass • Water volume
Body Composition • We’ve talked about muscle mass, so this section will focus on fat management.
Body Composition Obesity • May be functionally defined as the percent body fat at which disease risk increases.
Body Composition • Obesity is an excessive amount of body fat relative to body weight and is not synonymous with overweight.
Body Composition • In epidemiological studies: • overweight is >120% of desirable weight • body mass index (BMI) >29.3 for women and 29.8 for men.
Body Composition • Because these overweight criteria do not take into account the composition of the excess weight, they are limited as indexes of obesity and may result in misclassifications of obesity.
Body Composition • An excessive percentage of body fat is associated with increased risk for development of hypertension, diabetes, CAD, and other chronic diseases.
Body Composition • The prevalence of hypercholesterolemia, hypertension, and Type II diabetes is, respectively 2.9, 2.1, and 2.9 times greater in overweight than in non-overweight persons.
Body Composition • Recent evidence indicates that “central obesity” is particularly problematic. • Abdominal fat is strongly associated with diseases such as CHD, diabetes, hypertension, and hyperlipidemia.
Body Composition • Android and Gynoid Obesity
Body Composition • In addition, obesity often carries negative social stigma and is associated with a reduced physical working capacity.
Body Composition • At the opposite extreme, individuals with too little body fat tend to be malnourished.
Body Composition • These people have a relatively higher risk of fluid-electrolyte imbalances, osteoporosis and osteopenia, bone fractures, muscle wasting, cardiac arrhythmias, and sudden death, edema, and renal and reproductive disorders.
Body Composition • One disease associated with extremely low body fat levels is anorexia nervosa.
Body Composition • Anorexia nervosa is an eating disorder found primarily in females and is characterized by excessive weight loss.
Body Composition • Compared to normal women, anorexics have extremely low body fat levels (8 to 13%), signs of muscle wasting, and less bone mineral content and bone density.
Body Composition • Combating obesity and eating disorders is not an easy task.
Body Composition • Many overweight and obese individuals have incorporated patterns of overeating and physical inactivity into to their lifestyles, while others have developed food and/or exercise addictions.
Body Composition • Many are lured by fad diets and exercise gimmicks, and some resort to extreme behaviors such as avoiding food, bingeing and purging, and exercising compulsively.
Body Composition • Body fat is reduced when a chronic negative caloric balance exists.
Body Composition • It is recommended that both an increase in caloric expenditure through exercise and a decrease in caloric intake be used to accomplish this goal.
Body Composition • Exercise increases energy expenditure and slows the rate of fat-free tissue loss that occurs when a person loses weight by severe caloric restriction.
Body Composition • Exercise also helps maintain the resting metabolic rate and thus the rate of weight loss.
Body Composition • Hormones play an important role in regulating metabolism.
Body Composition • Thyroxine is extremely important in regulating resting metabolic rate. • Underproduction of thyroxine can reduce RMR 30 to 50%.
Body Composition • Growth hormone, epinephrine, norepinephrine, and various sex hormones may elevate RMR as much as 15 to 20%.
Body Composition • These hormones increase during exercise and may be responsible for the elevation in resting metabolic rate after cessation of exercise.
Body Composition • Improper diet, overeating, hormonal disturbances, and physical inactivity may create a positive energy balance, which leads to excessive weight gain and obesity.
Body Composition • Lack of physical activity rather than overeating is a more common cause of obesity in children and adults.
Body Composition • Obese individuals are invariably sedentary and many have had poor experiences with exercise in the past.
Genetics • Only 10% of children who had normal-weight parents were obese.
Genetics • The probability of being obese is increased to 40% and 80%, respectively, if one parent or both parents are obese.
Genetics • Although these data suggest a strong genetic influence, they do not rule out environmental influences such as eating and exercise habits.
Genetics • Approximately 25% of the variability among individuals in absolute and relative body fat is attributed to genetic factors and 30% is associated with cultural (environmental) factors.
Body Composition • The exercise professional should interview the obese participant to determine past exercise history, potential scheduling difficulties, and the locations where exercise might be performed (e.g., sports club, home, street, school gym, or track, etc.)
Body Composition • This may increase adherence to an agreed upon exercise program.
Psychological Issues • Overweight and obesity may be caused by psychological factors.
Psychological Issues • Some overweight and obese individuals use food and eating as a coping mechanism or defense mechanism.
Psychological Issues • Compulsive eaters may eat to cope with feelings of insecurity, anxiety, depression, loneliness, stress, and tension rather than to satisfy hunger.
Psychological Issues • In this case, the individual needs to recognize the fact that he or she is eating compulsively, identify the underlying reasons for this behavior, and take steps to modify these behaviors.
Psychological Issues • Encourage clients with eating disorders to seek psychological counseling.
Body Composition • Obesity is associated with increases in both the number (hyperplasia) and size (hypertrophy) of fat cells.
Body Composition • An increase in fat cell number occurs rapidly during the last trimester in the womb through the first year of life, around ages 7-8, and again during adolescence, but remains fairly stable in adulthood except in cases of morbid obesity.
Body Composition • Fat cells grow in size when excess fat is stored in the cells as triglycerides. • Weight gain in adults is typically characterized by the enlargement of existing fat cells, rather than the creation of new fat cells.
Body Composition • Similarly, caloric restriction and exercise are effective in reducing fat cell size, but not the number of fat cells.
Body Composition • The key to preventing obesity is to closely monitor the dietary intake and energy expenditure, especially during the adolescent growth spurt and puberty.
Body Composition • This could potentially retard the development of new fat cells and control the size of existing fat cells.
Lifestyle Change • Adoption of a physically active lifestyle. • Adoption of dietary guidelines. • (US Dept. of Health and Human Services, 1995)
Dietary Guidelines • Eat a variety of foods. • Balance the food you eat with physical activity. • Choose a diet with plenty of grain products, vegetables, and fruits.
Dietary Guidelines • Choose a diet low in fat, saturated fat, and cholesterol. • Choose a diet moderate in sugars. • Choose a diet moderate in salt and sodium.