Body fat testing, sometimes called body composition testing, is an important measurement in fitness. Body fat testing estimates what percentage of body weight is represented by fat versus lean body (muscles, bones and organs). Through body fat testing, a fitness professional can determine reasonable fitness goals or gauge the effectiveness of an exercise or nutritional program.
Hydrostatic Weighing
Hydrostatic weighing is considered by the American Council on Exercise to be the most accurate form of body fat testing. To determine body fat percentage through hydrostatic weighing, the subject is weighed on dry land. Next, the subject is weighed while completely submerged in a pool or tank of water. Body fat percentage is calculated based on the difference between the subject's weight on dry land versus underwater. Although accurate, hydrostatic weighing is rarely used outside of the clinical setting due to the facility requirements.
Skinfold Calipers
Skinfold measurement is a body fat testing method recommended by the National Strength and Conditioning because it offers a balance of accuracy and convenience. To estimate body composition using a skinfold caliper the subject's skin is pinched at between two and seven sites throughout the body. Once pinched, the skin's thickness is measured by the caliper. Body fat percentage is estimated based on the thickness of the skin at each site. Although accurate when performed by a skilled trainer or physician, skinfold testing can be uncomfortable and embarrassing for the subject. For morbidly obese subjects, the caliper may not be able to accurately pinch the skin.
Bioelectrical Impedance Analysis
Bioelectrical impedance analysis, although not as accurate as hydrostatic weighing or skinfold calipers, is the simplest body fat test to perform. Using a hand-held device or conductors build into a bathroom scale, a mild electrical current is put through the subject's body. Body fat percentage is estimated based on the amount of resistance to the current. The test works based on the fact that muscle contains more water than fat and is therefore a better conductor. Although not accurate enough for the clinical setting, bioelectrical impedance testing does have the advantage of being the least intrusive of the common testing methods.
References
- ACE Personal Trainer Manual: The Ultimate Resource for Fitness Professionals, 3rd Edition by Cedric X. Bryant and Daniel J. Green; 2003
- "Essentials of Strength Training and Conditioning - 3rd Edition"; National Strength and Conditioning Association; 2008
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