Is New Obesity Scale Better Than BMI?

By Jenny Everett,SELF magazine

The quick-and-dirty way to determine if your weight is within a healthy range has long been to calculate your Body Mass Index: Your weight in kilograms divided by your height in meters squared (don't worry, there are plenty of simple online calculators!)

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In recent years, however, experts have become increasingly outspoken about the fact that the formula isn't entirely accurate across all ethnic groups. It also doesn't take muscle mass into consideration, which means it may overestimate body fat in athletes and people with lots of muscle and underestimate body fat in those who don't have much muscle.

Now, U.S. researchers say they've come up with formula that is more accurate.

Called Body Adiposity Index (BAI), the new formula uses height and hip measurements to assess body fat. And, so far, it has been validated in African American and Hispanic populations, with additional research planned to determine how accurate it is among whites and other ethnic populations.

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The actual formula, for all you math whizzes out there, is hip circumference in centimeters divided by height in meters times the square root of height minus 18.

While exercise physiologist Fabio Comana, spokesman for the American Council on Exercise (ACE), agrees that the BMI formula could use improvement, he told SELF that he sees BAI as having similar limitations.

For one, the researchers admit that this system is imperfect when it comes to lean individuals (less than 10 percent body fat) and athletes with a large amount of muscle mass. For example, the BAI system measures Comana, an athlete, at 17.24 percent body fat, which is about 5 percent higher than he actually is.

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"It shows promise and I like the fact that an alternative method may be within our reach," he says. "But I think it still is in need of refinement and additional validation."

Bottom line: Unless you're under 18, over 65 or muscular enough to kick Hugh Jackman's butt, BMI remains a solid way to evaluate your body composition.

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Photo Credit: Condé Nast Digital Studio