Assessment of Body Composition
The best way to determine your level of fitness is to measure your lean body mass. Lean body mass is defined as, “anything that is not fat or water.” It is the total weight of your bones, muscles and organs.
While there are many methods for accessing lean body mass, hydrostatic (underwater) weighing is considered the gold standard. But since this method is impractical, we use skinfold measurements with the Jackson-Pollack formula.
The equations for this method were derived by taking measurements from a large group and analyzing the data to determine the precise locations of the skinfold sites as well as the mathematical relationship that best correlates to the hydrostatic measurement.
How do you measure your lean body mass?
Using a body fat caliper, measure the amount of fat under your skin at the three different sites illustrated on the Body fat Calculator page and enter the information into the windows provided. The drawings show where you should pinch and raise the fatfold. All measurements should be taken from the right side regardless of which hand you use to write.
Once you have your percentage of body fat, multiply that number by your total body weight. That number is the weight of your body fat. Then subtract that number from your total weight. That number is your lean body mass.
Let’s take a 100 pound woman with 25 percent body fat for example. Multiply 100 x .25 = 25 pounds. That’s the amount of fat she has on her body. Then subtract 100 – 25 = 75 pounds. That’s her lean body mass.