For years, healthy-weight guidelines have focused on a measure called body mass index (BMI), which is a person’s weight in kilograms divided by his or her height in meters squared.

But recently, BMI has been criticized because a truly fit person can have a high measure that (wrongly) suggests he or she is unhealthy (muscle weighs more than fat). And two people with the same BMI at any level can have very different percentages of body fat; and it can be distributed across the body in very different locations.

That realization led the American Medical Association to adopt a new policy in 2023, encouraging doctors to avoid relying on BMI alone to diagnose obesity.

Researchers have now proposed using the BRI — body roundness index — instead. That measure puts waist circumference into the equation, because visceral belly fat powerfully increases risks for heart attack, stroke, cancer, kidney disease, and dementia.

As researchers work to develop a BRI chart, you can use the Centers for Disease Control and Prevention's recommendations for waist size as a guide to a healthy BRI: 35 inches or less for women; 40 inches or less for men.

To correctly measure your waist, you have to stand up. Place a tape measure around your middle at your belly button. Keep the tape snug but not compressing the skin. Measure your waist after you breathe out, sucking in your belly.