Body mass index (BMI) is an index widely used to define obesity. BMI does not always accurately indicate the degree of fatness. The degree of central fat distribution may be more closely tied to metabolic risks than BMI. Measurement of the degree of central fat distribution thus appears to be important for the early detection of subsequent health risks, even among those of normal weight. Waist-to-height ratio (W/Ht) corresponds better to metabolic risk than BMI.