Body Mass Index (BMI) is a value calculated from one's height and mass/weight, and can be used to determine one's general body type and as a very loose metric for health. Keep in mind that since BMI uses one's weight, the calculation does not differentiate between bodyfat and muscle. For example, eight-time Mr. Olympia Ronnie Coleman had a BMI of 41.8 in his peak competition weight, which would categorize him as "obese".