Body Composition
Body Composition
The body-mass index (BMI) is a number reflecting the percentage of body fat in proportion to lean body mass (bone, muscle, tissue, organs, and blood). Experts say it is a better indication of what shape you’re in than simple by-the-scale weight. Tests for BMI can be done in several ways, but it is virtually impossible to do any of them,except the tape-measure test, yourself:
? Pinch test (technically, anthropometric test). The tester uses a tong-like skin-fold caliper to pinch the skin, fat, and underlying adipose tissue away from your muscles in about half a dozen places on your body. The numbers displayed on the caliper translate into your BMI.
? Tank test. You sit on an underwater scale in a large tank. You exhale until there is no more air in your lungs and then submerge completely for five seconds until your weight is recorded on the scale. Your underwater weight is plugged into a formula that calculates your BMI.
? Bioelectrical impedance analysis. Electrodes are attached to your foot and hand. A painless signal between the two electrodes can determine your BMI because the signal travels at different rates through fat and muscle. The margin of error is greatest in people who are very overweight or underweight.
? Analyzer scale. This calculates various personal data from a statistical input and a 10-second weigh-in. The unit was developed by a Japanese company called Tanita. Input includes your weight, height, gender, clothing weight, and mode (adult, adult athlete, or child). The printout provides your actual body weight, body-mass index, impedance, fat mass, lean body mass, and percentage of body weight from fat and water.
? Tape-measure test. This does not measure your BMI, but it’s an easy way of checking how many inches you’ve lost. You can do it yourself at home. Use a tape measure on the places where fat is stored: waist, widest part of the hips, chest, upper arm, and thigh.
Another way to evaluate how close you are to a normal weight range is to look at your body-mass index, as expressed in percentage of body fat, and see where it falls. The lower the percentage of body fat, the low Body-Mass Index (in percentages)
Males Females
Slightly underweight <20.7 <19.1
Normal weight 20.7-26.4 25.8-27.3
Slightly overweight 26.4-27.8 25.8-27.3
Overweight 27.8-31.1 27.3-32.2
Very overweight 31.1-45.4 32.3-44.8
Morbidly obese >45.5 >44.8
Each body-composition test has a statistical margin for error, so select one test as a same person at the same place to provide the best indication of changes in your BMI.