Belly fat may be a better predictor of heart disease risk than BMI, study finds

Your tape measure can tell you more about your heart health than you realize.

In a study following over 250,000 adults over 20 years, researchers found that body mass index (BMI) measurements used traditionally for years as a predictor of heart disease risk may not be the most accurate measure when looking at nine outcomes, including heart attacks, strokes and heart failure.

Researchers looked at waist circumference and waist-to-hip ratio. Nearly one in five of those with normal BMI, but a high waist-to-hip ratio would have up to 50% higher risk for several of the heart disease outcomes, according to the study, published Tuesday in JACC, the journal of the American College of Cardiology.

On the other hand, among individuals with obesity, nearly 10% had lower waist circumference and when compared to their counterparts with normal weight and low waist circumference, the majority showed no significant difference in heart health risk.

Central adiposity, or the fat around our belly area, may provide a clearer picture of cardiovascular health, according to Dr. Tara Narula, ABC News chief medical correspondent and a board-certified cardiologist.

"Body mass index doesn't tell us about fat versus lean mass. It doesn't tell us about the distribution of the fat," Narula, who was not involved with the study, said Wednesday on "Good Morning America."

Visceral fat, the fat stored around organs, may lead to metabolic dysregulation, increasing inflammation, and raising blood pressure, blood sugar, and cholesterol levels.

For women, a waist circumference of around 35 inches and a waist to hip ratio of 0.85 are considered elevated, while for men, these thresholds are around 40 inches and a waist-to-hip ratio of greater than 0.90.

If you find yourself in the elevated category, this may mean a conversation with your doctor to evaluate your risk factors.

According to Narula, you can take your own measurements at home. Ensure you measure without clothes on, grab a flexible tape measure and measure at the highest point of your waist. For your hips, measure them at the widest point, then divide the waist measurement by the hip measurement.

Ultimately, Narula said she believes the study's findings may be even more important for medical practice, particularly in identifying people whose cardiovascular risk may be higher, or lower, than their BMI alone would suggest.

"It tells us we really should be adding this into how we inform patients in the office using those waist markers," she said.

Onaola Adedeji, MD, is a resident physician in Family Medicine with Obstetrics and Lifestyle Medicine and a member of the ABC News Medical Unit.

Dr. Wendy Zhuo is a family medicine resident physician at Emory University and a member of the ABC News Medical Unit.