Q. How does the BOD POD work?

The BOD POD system accurately measures body composition by determining body volume and body weight. Once those two variables are determined, body density can be computed and inserted into an equation to provide % fat measurements. Body weight is easily determined by the use of an accurate scale. Body volume is determined by applying the gas law (p1V1=p2V2), an expansion of Boyle’s Law, pV=c. The BOD POD measures volume by monitoring changes in pressure in a closed chamber. These pressure changes are achieved by oscillating a speaker mounted between the front testing chamber and a rear reference chamber, which causes complementary pressure changes in each chamber. The pressure changes are very small and are not noticed by the individual being tested.

Two measurements are performed to determine body volume. The volume of the subject chamber while empty is the first measurement taken by the BOD POD. The second measurement is the volume of the subject chamber with the subject inside. By subtraction, the volume of the subject is determined. Combined with the measurement of mass, the subject’s density is determined and subsequently their body composition is determined.