BODY COMPOSITION (Why your weight isn't a good indication of health.) Body Composition is the technical term used to describe the different components that, when taken together, make up a person's body weight. Cobourg Collegiate Institute 1
Body Tissues The human body is composed of a variety of different tissue types. The so called 'lean' tissues, (muscle, bone, and organs) is metabolically active, while "non lean tissue" (adipose tissue or fat) is not. Because scales can't determine the lean to fat ratio of that weight. An individual can be "overweight" and not "over fat." A bodybuilder, for example, may be 8% body fat, yet at two hundred and fifty pounds may be considered "over weight" by a typical height weight chart. Therefore, these charts are not a good indication of a person's ideal body weight for optimal health, much less for athletic performance. There are several different methods of assessing the percent of fat vs. lean mass of an individual. These methods are referred to as Body Composition Analysis. The gold standard of body composition analysis is hydrostatic or hydrodensitometry. Although, because it is time consuming, cumbersome, and complicated, most physiologists turn to skinfold measurements, as an acceptable alternative means of assessment. Skinfold measures, when performed by a trained, skilled, tester, are up to 98% accurate. Bio Impedance (electronic fat analyser) is another common, yet controversial method of assessing body fat percentage. Cobourg Collegiate Institute 2
What should your body fat percent be? A better question might be, "What is your ideal weight? Body fat percent varies considerably for men and women, and age. However, there are some standards. The minimum percent body fat considered safe and acceptable for good health is 5% for males and 12% for females. The average adult body fat is closer to 15% 20% for men and 20% 25% for women. Athletes, typically, find themselves at the low end of this scale. Optimal levels of body fat are much lower for those striving for high level performance. Ranges for professional athletes are quite a bit lower than for the average, healthy individual. Much of this difference can be attributed to the increased lean weight (muscle mass) of top athletes. The impact of body size on performance is one consideration that may correlate with body fat. Cobourg Collegiate Institute 3
While levels of body fat seem to be related to performance, body composition alone has never been a great predictor of sports performance. Several studies have suggested that percent body fat is inversely related to maximal aerobic capacity (endurance). Lean muscle mass seems to be positively related to performance in sports where the ability to generate maximal force is required. The body fat percents for elite athletes vary largely by sport. Clearly, the association between low body fat and improved performance is not precise, and there is little evidence of performance benefits when male athletes drop under 8% and women drop under 14% body fat. Cobourg Collegiate Institute 4
How Low Is Too Low? Athletes can take this "low body fat in the name of improved performance" idea too far. While the average body fat percent in the North America and Europe is increasing, low body fat percent is clearly a health problem. The female athlete triad of disordered eating, amenorrhea, and osteoporosis is a relatively new phenomenon. Women athletes who strive for better performance and lower body weight, often find themselves caught in a negative spiral that actually leads to decreased performance and health risks. Female Athlete Triad is a syndrome in which eating disorders, amenorrhoea and decreased bone mineral density (osteoporosis) are present. Also known simply as the "Triad", this condition is seen in females participating in sports that emphasize leanness or low body weight. The Triad is a serious illness with lifelong health consequences and can potentially be fatal Cobourg Collegiate Institute 5
How Much Is Too Much? Just as too little body fat can create some pretty devastating physiological complications, too much body fat can have equally harmful effects. Once men creep up over 25% and women over 32% fat, there is a dramatic correlation with illness and disease. Cobourg Collegiate Institute 6
Isn't Body Composition Genetic? While some aspects of your body composition are based on heredity (such as where you tend to store excess fat), for the vast majority of the population percent body fat is related to lifestyle. After about age 16, changes in body fat are due to changes in fat cell size not number. These cells expand (or shrink) to accommodate excess calorie storage. HYPERTROPHY vs HYPERPLASIA Cobourg Collegiate Institute 7
Can I Change My Body Composition? YES! To increase or decrease your percent of body fat you need to create the right balance between the calories you consume and the calories you burn. The most effective way to do this is to decrease your consumption of fat and increase your activity level. Aerobic exercise is a very effective way to decrease body fat, however, you must combine strength training in order to maintain or gain muscle mass and tone. If you haven't been active, you may want to begin with 15 minutes of exercise and gradually increase. If you are beginning a new exercise program, you are advised to first consult your physician. Cobourg Collegiate Institute 8