Body Composition zBody composition involves all components of the body including: zFat mass zMuscle mass zBone mass zWater volume

Body Composition zWe’ve talked about muscle mass, so this section will focus on fat management.

Body Composition Obesity zMay be functionally defined as the percent body fat at which disease risk increases.

Body Composition zObesity is an excessive amount of body fat relative to body weight and is not synonymous with overweight.

Body Composition zIn epidemiological studies: zoverweight is >120% of desirable weight zbody mass index (BMI) >29.3 for women and 29.8 for men.

Body Composition zBecause 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 zAn excessive percentage of body fat is associated with increased risk for development of hypertension, diabetes, CAD, and other chronic diseases.

Body Composition zThe 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 zRecent evidence indicates that “central obesity” is particularly problematic. zAbdominal fat is strongly associated with diseases such as CHD, diabetes, hypertension, and hyperlipidemia.

Body Composition zAndroid and Gynoid Obesity

Body Composition zIn addition, obesity often carries negative social stigma and is associated with a reduced physical working capacity.

Body Composition zAt the opposite extreme, individuals with too little body fat tend to be malnourished.

Body Composition zThese 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 zOne disease associated with extremely low body fat levels is anorexia nervosa.

Body Composition zAnorexia nervosa is an eating disorder found primarily in females and is characterized by excessive weight loss.

Body Composition zCompared 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 zCombating obesity and eating disorders is not an easy task.

Body Composition zMany 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 zMany 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 zBody fat is reduced when a chronic negative caloric balance exists.

Body Composition zIt 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 zExercise 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 zExercise also helps maintain the resting metabolic rate and thus the rate of weight loss.

Body Composition zHormones play an important role in regulating metabolism.

Body Composition zThyroxine is extremely important in regulating resting metabolic rate. zUnderproduction of thyroxine can reduce RMR 30 to 50%.

Body Composition zGrowth hormone, epinephrine, norepinephrine, and various sex hormones may elevate RMR as much as 15 to 20%.

Body Composition zThese hormones increase during exercise and may be responsible for the elevation in resting metabolic rate after cessation of exercise.

Body Composition zImproper diet, overeating, hormonal disturbances, and physical inactivity may create a positive energy balance, which leads to excessive weight gain and obesity.

Body Composition zLack of physical activity rather than overeating is a more common cause of obesity in children and adults.

Body Composition zObese individuals are invariably sedentary and many have had poor experiences with exercise in the past.

Genetics zOnly 10% of children who had normal- weight parents were obese.

Genetics zThe probability of being obese is increased to 40% and 80%, respectively, if one parent or both parents are obese.

Genetics zAlthough these data suggest a strong genetic influence, they do not rule out environmental influences such as eating and exercise habits.

Genetics zApproximately 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 zThe 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 zThis may increase adherence to an agreed upon exercise program.

Psychological Issues zOverweight and obesity may be caused by psychological factors.

Psychological Issues zSome overweight and obese individuals use food and eating as a coping mechanism or defense mechanism.

Psychological Issues zCompulsive eaters may eat to cope with feelings of insecurity, anxiety, depression, loneliness, stress, and tension rather than to satisfy hunger.

Psychological Issues zIn 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 zEncourage clients with eating disorders to seek psychological counseling.

Body Composition zObesity is associated with increases in both the number (hyperplasia) and size (hypertrophy) of fat cells.

Body Composition zAn 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 zFat cells grow in size when excess fat is stored in the cells as triglycerides. zWeight gain in adults is typically characterized by the enlargement of existing fat cells, rather than the creation of new fat cells.

Body Composition zSimilarly, caloric restriction and exercise are effective in reducing fat cell size, but not the number of fat cells.

Body Composition zThe key to preventing obesity is to closely monitor the dietary intake and energy expenditure, especially during the adolescent growth spurt and puberty.

Body Composition zThis could potentially retard the development of new fat cells and control the size of existing fat cells.

Lifestyle Change zAdoption of a physically active lifestyle. zAdoption of dietary guidelines. y(US Dept. of Health and Human Services, 1995)

Dietary Guidelines zEat a variety of foods. zBalance the food you eat with physical activity. zChoose a diet with plenty of grain products, vegetables, and fruits.

Dietary Guidelines zChoose a diet low in fat, saturated fat, and cholesterol. zChoose a diet moderate in sugars. zChoose a diet moderate in salt and sodium.

Dietary Guidelines zIf you drink alcoholic beverages, do so in moderation.

Behavior Modification zBehavior modification techniques can help people make these lifestyle changes.

Behavior Modification zExercise specialists, nutritionists, and psychologists need to work together to help their clients, especially obesity prone individuals, modify their physical activity and eating attitudes and behaviors.

Body Comp. - Fat Loss zThe initial exercise prescription should be based on low intensity and progressively longer durations of activity.

Body Composition zOn the basis of each person’s response to the initial exercise program, the exercise professional should eventually work toward increasing the intensity to bring the person into a target heart rate range suitable for cardiorespiratory conditioning.

Body Composition zThe higher intensity will allow for a shorter duration per session, or fewer sessions per week for the same weekly energy expenditure.

Body Composition zIn addition, the transition to higher intensity exercise will increase the number of opportunities to incorporate activities that naturally require a high rate of energy expenditure.

Body Composition zHowever, for many (especially older) obese subjects, a walking or other low intensity exercise program may be all they desire, and movement toward a more intense program may not be warranted.

Body Composition zThe needs and goals of the obese subject must be individually matched with the proper exercise program to achieve long- term body composition management.

Caloric Balance zBody composition is determined by a complex set of genetic and behavioral factors.

Caloric Balance zThough the contributing variables are many, the fundamental determinant of body weight and body composition is caloric balance.

Caloric Balance zCaloric balance refers to the difference between caloric intake and caloric expenditure.

Caloric Balance zThe First Law of Thermodynamics states that energy is neither created nor destroyed; therefore, body weight is lost when caloric expenditure exceeds caloric intake (negative balance) and weight is gained when the opposite situation exists.

Caloric Balance zOne pound of body fat (adipose tissue) is equivalent to approximately 3500 kcal of energy.

Caloric Balance zAlthough it is predictable that shifts in caloric balance will be accompanied by changes in body weight, the nature of the weight change varies markedly with the specific behaviors that lead to the caloric imbalance.

Caloric Balance zFor example, fasting and extreme caloric restriction (starvation and semi-starvation diets) cause substantial losses of water and fat-free tissue.

Caloric Balance zIn contrast, an exercise-induced negative caloric balance results in weight loss consisting primarily of fat.

Caloric Balance zHigh resistance exercise programs may lead to a gain in fat-free weight, while cardiorespiratory endurance training usually results in a maintenance of (or slight increase in) fat-free weight.

Caloric Balance zBoth types of programs can contribute to a loss of body fat, although aerobic activity is more efficient because it involves a sustained, high rate of energy expenditure.

Recommendations zFor most persons, the optimal approach to fat loss combines a mild caloric restriction with regular endurance exercise and avoids nutritional deficiencies.

Recommendations zA desirable fat loss program is one that meets the following criteria:

Recommendations z1. Provides intake not lower than 1220 kcal/day for normal adults and ensures a proper blend of foods to meet nutritional requirements. y(Note: this requirement may not be appropriate for children, older individuals, and athletes).

Recommendations z2. Includes foods acceptable to the dieter in terms of socio-cultural background, usual habits, taste, costs, and ease in acquisition and preparation.

Recommendations z3. Provides a negative caloric balance (not to exceed 500 to 1000 kcal/day), resulting in gradual weight loss without metabolic derangement, such as ketosis.

Recommendations z4. Results in a maximal weight loss of 1 kg/week.

Recommendations z5. Includes the use of behavior modification techniques to identify and eliminate diet habits that contribute to malnutrition.

Recommendations z6. Includes an exercise program that promotes a daily caloric expenditure of 300 or more kcal. zFor many participants, this may be best accomplished with low intensity, long duration exercise, such as walking.

Recommendations z7. Provides that new eating and physical activity habits can be continued for life in order to maintain the achieved lower body weight.

Caution zIn designing the exercise component of a weight loss program, the balance between intensity and duration of exercise should be manipulated to promote a high total caloric expenditure (300 to 500 kcal per session and 1000 to 2000 kcal per week for adults).

Caution zObese individuals are at an increased relative risk for orthopedic injury, and this may require that the intensity recommended for improvement of cardiorespiratory endurance.

Caution zNon-weight bearing activities (and/or rotation of exercise modalities) may be necessary and frequent modifications in frequency and duration may also be required.

Setting Goals zA healthy body weight is based on the client’s present FFM and % BF goal.