Is BMI an Accurate Way to Measure Body Fat?

Body Mass Index (BMI) is a mathematical formula and divides a person's weight by the square of their height. The answer falls into one of eight categories and indicates the person's bodyweight, from very severely underweight to very severely obese. A high BMI can indicate a high body fat and be used to screen for possible health problems.

But BMI is not a perfect measurement and may actually overestimate or underestimate a person's body fat.

• BMI doesn't distinguish between body fat and muscle mass. Muscle weighs about 18 percent more than the same amount of fat. So, according to BMI, the muscled person is more overweight than a sedentary person.
• BMI is also not reliable to use on elderly adults, who continue to lose muscle and bone mass with age. An overweight older adult may appear to be within a normal BMI range.
• The BMI calculation is based on Caucasian body types and may not be appropriate for people of other ethnicities.