We've long held that using the "Body Mass Index" (BMI) as a tool for measuring obesity is wrongheaded. BMI is a simplistic measure that only combines height and weight—ignoring muscle mass—which leads to erroneous classifications. Even the Centers for Disease Control and Prevention has cast doubt on its usefulness. So it wasn't surprising to read yesterday that the British National Health Service (NHS), which measures schoolchildren's BMI and sends "warning letters" to parents of supposedly "overweight" kids, has made a number of big fat screw-ups.
