Large Study Reveals Waist Measurements Better Predict Heart Risks Than BMI Alone

A major new study published in the Journal of the American College of Cardiology (JACC) challenges the long-standing reliance on Body Mass Index (BMI) as the primary tool for assessing obesity and cardiovascular risk. Researchers found that individuals classified as normal weight or overweight by BMI but with high waist circumference or waist-to-hip ratio faced a 15% to 50% higher risk of heart attack, stroke, heart failure, and atrial fibrillation. The study underscores the importance of considering fat distribution, not just total body weight, in cardiovascular risk assessment.

BMI, which calculates weight relative to height, has been widely used for decades as a simple indicator of obesity-related health risks. However, it does not differentiate between muscle and fat mass or indicate where fat is stored. Dr. Anat Berkovich, deputy head of cardiology at Sheba Medical Center, explains that visceral fat around internal organs, particularly in the abdomen, is metabolically active and releases substances that increase inflammation and cardiovascular risk. Waist circumference serves as an indirect measure of this harmful visceral fat.

The study pooled data from 15 prospective cohort studies including 259,388 adults without coronary heart disease at baseline, with a median follow-up of 20 years. It examined nine cardiovascular outcomes and mortality, finding consistent associations between abdominal fat measures and increased risk. Notably, 5% of those with normal BMI had high waist circumference, and nearly 40% of overweight individuals had abdominal obesity undetected by BMI alone. Conversely, some classified as obese by BMI had low waist measurements and lower cardiovascular risk than expected.

Gender differences emerged in waist-to-hip ratio findings: men with obesity but normal fat distribution had reduced risk, while women’s risk remained elevated regardless of fat distribution. The study suggests that combining BMI with waist measurements provides a more accurate cardiovascular risk profile than BMI alone. Current European Society of Cardiology guidelines already recommend including waist circumference in risk assessments.

While the study is observational and cannot prove causality, its large size and long follow-up strengthen the evidence that fat distribution is a critical factor in cardiovascular health. Dr. Berkovich emphasizes the need for multiple measures to better evaluate cardiometabolic risk, especially in populations where BMI alone is insufficient.