MEASUREMENTS: Waist Size Helps Predict Heart Risk in Teenagers.

Using waist measurements together with body mass index may better predict a teenager’s cardiovascular risk than using B.M.I. alone, a new study finds.

Pediatricians and medical groups routinely use B.M.I. as a measure of unhealthy weight in children. But the index, calculated by dividing one’s weight in kilograms by the square of one’s height in meters, cannot differentiate between fatty and lean tissue. So an athletic, muscular teen could be classified as overweight or obese using B.M.I. alone.

Some researchers have proposed using waist circumference percentile — or a similar measure, waist-to-height ratio — as a better gauge of health. But the new study, published in Archives of Pediatrics & Adolescent Medicine, found that neither measurement alone was sufficient.

Anything’s better than BMI, which makes bodybuilders with 3% bodyfat measure as grossly obese, and which was never intended for individual evaluations.