Beyond the scale: how to measure whether you’re fat or not, from the Harvard Health Letter
Most of us have our private ways of assessing how fat we are. We feel our pants getting snug—or loose, if we're lucky. But there are more objective ways to answer the question. The January 2009 issue of the Harvard Health Letter provides a guide to three measures of fatness.
Body mass index, or BMI, is computed by taking your weight in kilograms and dividing it by the square of your height in meters. The BMI is easy to calculate, and in most people, it correlates reasonably well with overall body fat. It's also a good measure of health risk: as a rule, when BMIs go up, so do deaths, particularly from cardiovascular disease. But BMI doesn't distinguish whether the pounds are from fat or from fat-free tissue like muscle and bone. BMI also doesn't tell us about the type of fat we're carrying—a significant shortcoming, as the type of fat that builds up in the abdomen is believed to be particularly unhealthful.