equipment required: Near Infrared Interactance is measured using a computerized spectrophotometer, which has a single, rapid scanning monochromator and fiber optic probe.
procedure: This method uses the principles of light absorption and reflection to measure body fat. The measurement is taken on the person's dominant arm. A monochromator, or light "wand", sends a low-energy beam of near-infrared light into the biceps and penetrates the underlying tissue to a depth of one centimeter.
The energy is either reflected, absorbed, or transmitted, depending on the scattering and absorption properties of the biceps.
A detector within the wand measures the intensity of the re-emitted light.
Shifts in the wavelength of the reflected beam and a prediction equation are used to compute the percent body fat.
advantages: The measurement is safe and the equipment is portable and lightweight.
It requires little training to use.
disadvantages: This technique still lacks validation in humans, and may not accurately predict body fat across a broad range of fat levels.
It assumes fat is the arm is proportional to total body fat, which may not be true.
other comments: This method is based on what was developed by the United States Department of Agriculture to measure the body composition of livestock and the fat content of various grains.
products: Futrex: uses Near-Infrared light to directly measure percent body fat
