Body Composition - Overweight or Over Fat
Filed under: Exercise Science
A person's body is made up of many different components. Some of these components are bone, muscle, organs and fat. The ideal body composition varies in different sports, but in general the less body fat translates to increase performance. Athletic performance, therefore, relates to body type (size and shape) and body composition (muscle and fat).
The amount and percentage of the fat component is of greater importance to us as athletes. We have two types of fat, essential fat and non-essential fat. Essential fat is necessary for healthy living. It helps with temperature regulation, shock absorption, organ protection and transportation of important nutrients. Non-essential fat has no purpose and is the result of taking in more calories than we metabolize. Excessive body fat contributes no strength advantage to us and limits our endurance, speed and movement. Height and weight charts and body mass index are generalizations based on averages. These averages can be misleading because they only apply to approximately half of the population. Charts often do not take into consideration frame size and muscular development. They can be useful as general guidelines but must not be misinterpreted as absolute predictors of ideal body weight. The amount of body fat, often expressed as % body fat (%BF), is the most important predictor of what is normal or excessive in living a healthy life.
Unfortunately, Americans do not get enough exercise or follow a healthy diet. As we age and our metabolic rate slows, in addition to adopting a more sedentary lifestyle and eating the same amount of calories, fat accumulation increases and out muscle mass declines. A person can weigh the same at the age 50 as they did at age 20 but be unhealthy due to increased fat buildup and decreasing muscle mass. A study by Brozek and Keys showed the following changes in %BF with age:
AGE: 20 25 30 35 40 45 50 55
%BF: 10.3 13.4 16.2 18.6 20.7 22.5 23.9 25.0
Therefore, a person who weighs 180 lbs. at age 20 has approximately 18 lbs. of body fat and 162 lbs. of lean body mass (everything else). Without following an exercise program, at age 50, the same person still weighs 180 lbs., however, their %BF has increased to 43 lbs and the muscle mass has decreased to 137 lbs. Even though the weight is the same, they are becoming over fat.
The rate of change can be modified depending upon lifestyle. Those who chose to exercise regularly and follow a prudent diet, do not gain fat or lose muscle at the rate described above, but will maintain the proper body composition balance. The most important information obtained from monitoring %BF over time is the changes in lean body mass (muscle).