Body-fat scales: will they help?(Health & Fitness Section)(Buyers Guide)

Concerns about fat and obesity have spawned a new kind of bathroom scale, one that gives your weight and uses a weak electric current to measure the amount of fat on your frame.

Some manufacturers claim that body-fat percentage, which the scales measure, is key to health and fitness. But our tests suggest that the scales are not the most reliable measure of body fat. Meanwhile, our consultants--who have done the best research yet into the link between fat and health--say it's a mistake to make too strong a connection between health and the amount of body fat you have.

"The connection between body fat and health outcome has defied a simple answer," says Steven B. Heymsfield, M.D., co-director of the body-composition laboratory at St. Luke's-Roosevelt Hospital, in New York. "That's why there is not a standard for health based on body fat."

MEASURING BODY FAT

For years, people have gauged obesity with the body-mass index, or BMI. The formula considers height and weight, but not body-fat percentage. BMI is your weight in pounds times 703, divided by the square of your height in inches. To reckon your BMI, go to www.nhlbisupport .com/bmi/bmicalc.htm.

Large long-term studies of people in many countries have shown that those with a BMI below 25 have lower rates of diabetes, heart disease, high blood pressure, and overall mortality than do people with a BMI of 25 or more. A BMI of 30 or more means you're obese; your risk of disease and death rises more sharply.

Researchers have begun to relate measures of body fat with BMI calculations. However, no one knows what a healthy body-fat amount is, despite claims from the manufacturers of some body-fat scales.