There are many ways to measure body fat
December 28, 2004
People starting a fitness program might encounter any of a half
dozen methods of measuring body fat. Here are several outlined by
Shape Up America!, a nonprofit organization created by former Surgeon
General C. Everett Koop and devoted to weight control:
- Bioelectrical impedance: A scale-like device sends a small electrical
signal into the body and measures the body’s resistance
to the signal. Software in the device measures impedance and then
uses this and other information to measure body fat. This method
can overestimate fat in dehydrated people.
- Body mass index: A formula using weight and height determines
body mass, although this method does not distinguish between fat
and lean mass and can misclassify some people. To calculate BMI,
weigh yourself and convert the pounds to kilograms. Convert your
height to meters and square the number. BMI equals your weight
in kilograms divided by your height in meters squared. BMI calculators
are readily available online.
- X-ray scans: A table-mounted whole-body scanner is used to scan
the body, determining its amount of lean and fat mass. The test
is considered accurate, but it can be costly.
- Girth measurements. Measurements are taken on specific parts
of the body, and the result is entered into a formula that predicts
body fat. The measurements can be inaccurate for some people.
- Near-infrared interactance. A light "wand" held over
body parts emits a low-energy beam of near-infrared light, and
body fat is calculated using the principles of light absorption
and reflection. This method assumes arm fat is proportional to
total body fat, which is not necessarily true.
- Skinfold measurements. Calipers measure folds of skin and fat
at several points on the body, and the measurements are entered
into an equation to estimate total body fat. This method assumes
fat under the skin is proportional to total body fat, which is
not necessarily true, and requires experience using the calipers
accurately.
- Underwater weighing. The person being measured is weighed under
water, and body fat is calculated from equations based on the
density of the body.
Source:www.mailtribune.com
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