Body fat composition data provides details about changes in your lean mass and body fat mass. Hydrostatic weighing and air displacement plethysmography are two reliable methods for calculating body composition; however, they require expensive equipment. You can also estimate body fat composition using skinfold calipers and the Jackson-Pollack seven-site formula.
Body Composition Testing
Anthropometric techniques use skinfold thickness, which measures subcutaneous fat, to estimate body fat composition. Measure the thickness of up to nine skinfold sites on your body and plug the results into a formula to estimate your body fat. The Jackson Pollack formula uses the measurements from seven skinfold sites and personal information, including gender, age and weight, to calculate your body fat percentage. This formula can have an error margin up to 4 percent compared to the more advanced measurement methods.
Upper Sites
Six of the seven skinfold sites for the Jackson Pollack formula are on the upper body. Four of these sites are above the navel, and three are at or below the navel. The triceps skinfold is on the back of the upper arm, halfway between the shoulder and elbow. The chest measurement is a diagonal fold taken between the armpit and the nipple. The midaxillary site is a vertical fold taken under the arm in line with the bottom of the sternum. The subscapular measurement is a diagonal fold taken just below the shoulder blade.
Lower Sites
The suprailiac measurement is a diagonal fold taken just above the hipbone. The abdominal site is a vertical fold in line with and about 1 inch to the right of the navel. The thigh is the only lower body measurement in the Jackson Pollack formula. It is a vertical fold on the front of the thigh midway between the upper knee and the hip.
Technique
Take all skinfold measurements on the right side of the body. It may help to mark the site with a grease pencil before taking your measurements. Grab the fold with your thumb and index finger. Start with your fingers about 3 inches apart and grab the skin in a pinch. Place the jaws of the skin calipers about 1 cm below your fingers. Take measurements from all seven sites and then repeat. If the values at one site vary more than 2 or 3 mm, take more readings.
References
- "International Journal of Exercise Science"; Comparison of Body Composition Measurements Using a New Caliper, Two Established Calipers, Hydrostatic Weighing and BodPod; Erin E. Talbert, et al.; 2009
- ExRx.net: Skinfold Sites
- University of New Mexico; Body Composition Assessment; Len Kravitz, et al.
- Springfield Technical Community College; A Comparison of Various Methods for Assessing Body Composition; Robert H. Ferguson, et al.
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