Body mass index, known only slightly better as BMI, is one way to figure out how fat we are, and apparently, how healthy we are. A BMI of 25 or less is considered good, and higher than 25 is not good. And while the mathematical formula used to determine BMI is not simple: (mass (in pounds) divided by height (in inches squared) times 703, the concept is: weight divided by height. The mathematically challenged can find a BMI calculator here. Now comes a new study suggesting that the century and a half old formula is probably the best predictor we have of several health problems. Nicholas Bakalar reports in the New York Times that researchers studied data about BMI, body fat percentage, waist circumference and waist-to-height ratio on 12,294 men and women, then calculated how well each measure predicted various elements of the metabolic syndrome — high blood pressure, elevated fasting glucose, reduced HDL (or “good”) cholesteroland raised LDL (“bad” cholesterol). Here, according to Bakalar, is what they found: B.M.I. and body fat percentage were the best predictors of raised blood pressure, while waist circumference and waist-to-height ratio were good predictors of elevated fasting glucose and reduced HDL cholesterol. Body fat percentage was a slightly better predictor of increased LDL. None of the measurements was consistently better than B.M.I. as a predictor of all the risk factors. Read the study here.