Reach for your measuring tape instead of your scale to prevent heart attacks, say obesity experts in The Lancet. The best test for obesity—at least, when it comes to predicting heart attacks—is not body-mass index (BMI), but rather the waist-to-hip ratio.

Having a slimmer waist coupled with wider hips is a better indicator of reduced heart-attack risk than the much-touted body-mass index measurement—and the results ring true for both men and women in this worldwide study, particularly for Asian, Arab, and African heart-attack survivors. Body-mass index tends to particularly fail these groups, write the researchers.

While more research needs to be done to validate the desired waist-to-hip ratio, experts in metabolic syndrome—a cluster of factors known to put people at risk for heart disease and diabetes—say that a waist size of 35 inches or larger in women, and 40 inches or larger in men, increases risk.