BMI: Is it accurate for weightlifters?

Body mass index (BMI) uses your height and weight to calculate your percentage of body fat. For most people, BMI provides a reliable estimate of weight-related health risks. But it does have limitations. Because BMI doesn't differentiate between lean muscle and fat, it may overestimate body fat in people who have muscular builds, such as weightlifters. As a result, your BMI can be high but your disease risk still can be low.

At 5 feet 9 inches tall and 180 pounds, your BMI is 26.6. A BMI greater than 24.9 generally means you are considered overweight. (If you are Asian, overweight is defined as a BMI greater than 22.9.) However, if a significant portion of your weight is lean muscle and you exercise regularly, your health risks are likely to be the same as if your BMI was less than 25.

In addition to BMI, doctors have several other methods for determining whether you are overweight or obese. These include:

• Waist circumference
• Underwater weighing
• Measuring skin fold at three different body sites