Nutrition Science and Everyday Application - beta v 0.1

386 ALICE CALLAHAN, PHD, HEATHER LEONARD, MED, RDN, AND TAMBERLY POWELL, MS, RDN
data. There are several different methods used to measure body composition, each with
advantages and limitations. 6
• Skinfold test. This is a simple, non-invasive, and low-cost way to assess fat mass.
Calipers are used to measure the thickness of skin on three to seven different
parts of the body, and these numbers are then entered into a conversion equation.
Keep in mind that the accuracy of the skinfold test depends on the skill of the
person taking the measurements, the accuracy of the calipers, and the
appropriateness of the conversion equations. Best practice is for the same person
to take repeated measurements if using them to monitor changes over time.
Repeated measurements by different technicians, using different calipers, and
different conversion equations will yield very different results.
Figure 7.9. Calipers used to assess body fat during skinfold testing.
• Bioelectric Impedance Analysis (BIA). This is a simple, non-invasive, quick tool
that does not require extensive training. BIA estimates body composition by
sending a small amount of electricity through the body. Since water is a good
conductor of electricity, and lean body mass contains more water than fat, the rate
at which the current travels can be used to estimate percent body fat. Body fluid
levels must be normal with BIA, which is a limitation, since hydration can be