Body composition is the makeup of fat and fat-free mass in the body. Fat-free mass is anything that is not fat and can include water, bone, muscle, and skin. Fat mass is solely fat, found on the body and throughout the organs. Measuring body fat percentages can indicate the state of one's fitness as well as the risk for developing certain diseases.
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It is important to monitor body composition. Increased body fat can lead to an increase risk for developing certain diseases. According to David Nieman, author of "Exercise Testing and Prescription," an elevated body fat percentage can increase the risk of developing heart disease, diabetes, certain types of cancer and high blood pressure.
Body Fat Percentages For Women
The American College of Sports Medicine, or ACSM, recommends that women have a body-fat percentage of 20 percent to 32 percent. For women ages 40 to 49, the 50th percentile for body-fat composition is 26.4 percent. The 50th percentile is the average based on a comparison of peers of the same age range and gender. Since 26.4 percent falls in the recommended range, the 50th percentile is a good goal.
Body Fat Percentages For Men
For men, the ACSM recommends a body fat percentage of 10 percent to 22 percent. For males ages 40 to 49, the 50th percentile, or the average of those in the same age and gender range, for body-fat percentage is 21.1 percent. This is a valid goal for body fat percentage.
How It's Measured
The most common way to measure body-fat percentage is with skin fold calipers or through bio-electrical impedance. The method for measuring fat with calipers is somewhat complex and should involve an experienced professional, states Nieman. Seven sites around the body are pinched so that fat is isolated and measured with a caliper. The results are plugged into a calculation that accounts for gender and age and will estimate body fat percentage. Bio-electrical impedance passes a harmless electrical current through the body. Since muscle conducts electricity and fat does not, the machine can estimate the percentage of lean body mass versus fat mass. Bio-electrical impedance is possible to do without assistance and consumers can buy scales with this feature.
There are two major uncontrollable factors that may affect body-fat percentages, according to the ACSM. As a person ages, body fat percentages increase as muscle mass is lost. The second is gender. In general, women have a higher body-fat percentage that men.
There are ways to influence a person's body fat percentages. As a person ages, it is important to maintain physical activity. According to the "Physical Dimensions of Aging," sarcopenia occurs with age. Sarcopenia is a loss of muscle mass over time. Physical activity helps to decrease sarcopenia and can also decrease body fat. In addition to exercise, eating a healthy diet can decrease stored body fat. According to Nieman, a low-fat, calorie-controlled diet can reduce body weight and body fat.
REFERENCES & RESOURCES
- "Exercise Testing and Prescription", David C. Nieman, 2007
- "ACSM's Guidelines for Exercise Testing and Prescription",Whaley, Mithcell H., PhD, Brubaker, Peter H., Phd, Otto, Robert M., Phd (Eds.), 2006.
- "Physical Dimensions of Aging" Waneen W. Spiriduso, Karen L. Francis and Priscilla G. MacRae; 2005
- The Mayo Clinic: Body Fat Analyzers: How Accurat Are They?