Effective weight loss programs are not only measured by the numbers on the scale. To determine the success and efficiency of one's program, body fat percentage should be regularly calculated; once every week or two should be sufficient. There are many advanced and expensive techniques including bio-electrical impedance and hydrostatic weighing, as well as unreliable methods like body-mass indexing and girth measurements. However, the most cost effective method is by skinfold measurement using body fat calipers.
How to Calculate Your Body Fat Percentage
Step 1
Identify the correct sites for taking skinfold measurements. These include the thigh (mid-thigh), the abdomen (1 inch from belly button), suprailiac (just above hip-bone), midaxillary (just below the center of the armpit), chest (1 inch to the side of the nipple), triceps (middle and back of upper arm) and subscapular (just below the shoulder blade).
Step 2
Pinch the skin at the site between the thumb and index finger. Squeeze tightly, to the point of minor discomfort. Close calipers tightly around the pinch, 1cm from the fingers and to the depth of the pinch, and take the measurement.
Step 3
Go through all sites once, and repeat two more times. Take the average for the three measurements for each site. This is the measurement that you will use in calculating body fat.
Step 4
Use these measurements with the Jackson-Pollock body density equation. For males using seven skinfold sites, the equation is:
Body Density = 1.112 - (.00043499 x sum of seven measurements) + (.00000055 x (sum of measurements squared)) -- (.00028826 x age)
Using three skinfold sites, the equation is:
Body Density = 1.10938 - (.0008267 x sum of three measurements) +(.0000016 x (sum of measurements squared)) -- (.0002574 x age)
For females using seven sites, the equation is:
Body Density = 1.097 -- (.00046971 x sum of seven measurements) + (.00000056 x (sum of measurements squared)) -- (.00012828 x age)
And using three sites:
Body Density = 1.0994921 -- (.0009929 x sum of three measurements) + (.0000023 x (sum of measurements squared)) -- (.0001392 x age)
Step 5
Using the body density formula results, calculate body fat percentage with the Siri equation:
% BF = [(4.95/Body Density) -- 4.5] x 100
Tips and Warnings
- Have a friend help with the measurements. It can be difficult to reach certain sites by yourself, especially using all seven sites. If only using three sites, it is recommended to use the thigh, triceps and suprailiac. Take all measurements while standing. Take all measurements from the same side of the body. For the most accurate measurements, perform the test first thing in the morning.
Things You'll Need
- Skinfold calipers
- Calculator
References
- Siri, W. E. (1961). Body composition from fluid space and density. In J. Brozek & A. Hanschel (Eds.), Techniques for measuring body composition (pp. 223-244). Washington, DC: National Academy of Science.
- Jackson, A. S., & Pollock, M. L. (1978). Generalized equations for predicting body density of men. British Journal of Nutrition, 40, 497-504.
- Jackson, A. S., Pollock, M. L., & Ward, A. (1980). Generalized equations for predicting body density of women. Medicine and Science in Sports and Exercise, 12, 175-182.
Member Comments