Where you carrry your weight makes a difference: It’s less healthy to have much around your midsection. (Bigstock)

Most people know that BMI, or body mass index, is a fitness indicator calculated using your height and weight. Most people also know (don’t you?) that where you carry your weight makes a difference: It’s less healthy to have a disproportionate amount of weight around your midsection.

The April issue of O features a calculator aimed at factoring that belly fat, as well as your age, into the equation and assessing your relative risk of premature death. Called A Body Shape Index, or ABSI, it was developed by a father-and-son team — Jesse Krakauer, an endocrinologist, and Nir Krakauer, an assistant professor of civil engineering at City College of New York — in 2012, but it hasn’t gotten a lot of national attention.

The formula, which involves such complicated steps as calculating BMI, then raising it to the two-thirds power, can be found in the July 2012 issue of the journal PLOS One, where the authors also explain why they think it is a useful estimate of mortality risk. If you’d rather skip the science-speak, just go to www-ce.ccny.cuny.edu/nir/sw/absi-calculator.html and plug in your age, height, weight and waist measurement. If the Relative risk, BMI+ABSI” comes out as 1, that puts you at average risk of premature death for someone your age; less than 1 indicates less risk and greater than one means . . . well, you might want to start doing some crunches.