Want to Be Trendy? Check Your BMI At www.nhlbisupport.com/bmi/

Once only a measure used by health agencies, Body Mass Index, or BMI, is now the trendy gauge of girth as people pass over pounds as passé. You know the scales have tipped in BMI's favor when it gets face time in the Fashion & Style Section of the New York Times, and that's not the half of it: In September, Madrid passed a ban on runway models with BMI below 18.5, China has recently mandated that prospective adoptive parents for Chinese children have BMI under 40, and report cards in Arkansas and Tennessee now include students' BMIs as well as grades. BMI is calculated by dividing a person's weight in kilograms by his or her height in meters squared (try it yourself - with pounds and feet - at www.nhlbisupport.com/bmi/). Is BMI actually a good measure of metabolic health? In her Dec. 28 Times article titled "Quick, Do You Know Your BMI?", reporter Abby Ellin notes that caution is in order. The number "should not be the final word for measuring whether a person is under- or overweight to an unhealthy degree," she writes, because BMI is only one of several measures that matter. As she points out, BMI does not distinguish between fat and muscle mass, so Arnold Schwarzenegger as Mr. Universe was technically obese (with a BMI of 33). Some studies show that sedentary people with lower BMIs are actually at greater risk for diabetes and heart attacks than fit people with higher BMIs. Nonetheless, BMI remains a commonly accepted gauge of health because it's easy to calculate.