Move over BMI: It’s time for waist circumference to shine.

Since the 19th century, the body mass index scale, or BMI, has been the most reliable way to calculate a healthy body weight. The calculations categorize people into levels of normal weight, underweight, overweight, or obese depending on their weight to height proportions.

However, because BMI cannot distinguish between body fat and lean tissue, this measurement is not the most accurate way to assess your health in relation to your body weight.

For example, a professional football player who is 6 feet tall and weighs 230 pounds would be considered “obese” according to the BMI scale. But as an NFL athlete, most of that weight comes from lean tissue, not unhealthy body fat. In this case, BMI wrongly categorizes the player as “unhealthy” because muscle isn’t distinguished from fat.

The second problem with BMI is the fact that the measurement cannot tell us where the fat in our bodies is located. Fat around our belly is more dangerous than fat around arms and legs, because belly fat is linked to greater risk for chronic diseases like heart disease, diabetes, and high blood pressure.

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As The Today Show segment above notes, having the same BMI as someone else does not mean that you are at equal risk for the same things. Two people could have the same BMI, but completely different body shapes and body fat percentages. This single metric wouldn’t tell either very much about their disease risks.