Body fat percentage is the amount of fat versus the amount of muscle, bone and organ tissue in the body. There are two types of body fat, essential and storage. Essential body fat is the minimum amount of fat a person needs to survive, and storage fat is the remaining fat in the body. A normal body fat percentage for males is approximately 15 percent, and a normal body fat percentage for females is 26 percent.
Skin Calipers
Skin calipers function by taking a measurement of a fold of skin and the underlying layer of fat. The most common method is a four-site system. The measurement sites are the bicep, the tricep, below the shoulder blade (subscapular) and at the hip (suprailliac). These measurements are then added together and compared to a standardized chart to compute your body fat percentage. There are several equations available to calculate your body fat percentage from your skin fold values. A trained professional should take your measurements and use the appropriate equation for you. To see progress, the most accurate way is to have the same professional measure you each time.
Dual energy X-ray Absorptiometry
The dual energy x-ray absorptiometry (DEXA) scan is a type of x-ray that provides information on the ratio of body fat, muscle tissue and bone in specific parts of the body. Two x-ray beams at different frequencies are used to differentiate between bone, body fat and lean tissue. These images are much more complex than a normal x-ray, and must be read by a person specially trained in reading DEXA scans.
Air Displacement Plethysmography
The Bod Pod is the most common apparatus used for air displacement plethysmography. It is an egg-shaped chamber that measures your total body density (density=mass/volume). Lean tissue is denser than fat tissue, therefore the denser your body is, the leaner you are. The Siri Equation is used to calculate body fat from the total body density: percent fat = (495/density) - 450. In this test, you will sit inside the chamber, wearing form-fitting clothing and a cap to cover your hair. The test only takes five minutes, and the results are instant.
Hydrostatic Weighing
Hydrostatic weighing uses the difference between your "land weight" and "water weight" to determine your body fat percentage. Fat tissue is more buoyant than lean tissue, therefore the greater the difference in your land weight and your water weight, the more body fat you have. For this test, you stand on a scale before you get into the water to determine your land weight. You then enter the water tank and sit on the special chair, exhale, and submerge yourself under the water. At this time, your water weight will be recorded, and the tester can determine your body fat percentage.
Bioelectrical Impedance Analysis
Bioelectrical impedance analysis BIA uses electricity to determine your body fat percentage. With this technique, electricity is sent through the body and the level of impedance is measured. Lean tissue contains large amounts of water, and water is a good conductor of electricity and will not impede the electrical current. Fat, on the other hand, contains little water and will impede the electrical current. Therefore, the greater amount of energy that is lost in the body, the greater amount of body fat present. Several factors need to be considered for this test to be accurate. These are age, height, weight and sex. It is important that you be well hydrated for the most accurate results.
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