BMI Is Outdated. This Health Indicator Might Be Better.

Body mass index (BMI) has long been a standard to gauge patients’ health. But the measurement has grown increasingly controversial, and earlier this year, the American Medical Association (AMA) finally acknowledged that BMI should not be used on its own as a diagnostic tool for obesity. 

Now, there might be a more accurate health indicator to use instead. 

A new study published Thursday in JAMA Network Open found that measuring a person’s waist-to-hip ratio (WHR) is the best measure of a person’s body fat that is most strongly associated with adults’ mortality. 

The study analyzed data from the deaths of nearly 400,000 adults across the United Kingdom between 2006 and 2022. Researchers concluded that WHR, more than BMI and fat mass index, had the most consistent correlation with causes of death including cancer, cardiovascular disease and respiratory disease. 

BMI calculates a person’s weight versus their height, which medical experts have concluded does not necessarily give an accurate reading of a person’s health. “Higher BMI could either be beneficial or [detrimental] depending on clinical context,” researchers noted in the study. 

WHR is better, they argue, because it more accurately accounts for body composition and fat distribution.

For example, a person may have a low BMI but have a higher amount of abdominal fat mass that is detrimental to their health, researchers said. Doctors moving to use WHR alongside BMI may help them get a better idea of potential future health risks. 

Some limitations to the study: The correlation between WHR and mortality risk was disproportionately higher in men than women, and the study covered only data from white U.K. residents. (Interestingly, earlier this year, the AMA noted that BMI was inaccurate, in part, because it is based on measurements taken only from white populations.) Experts emphasized the need for further research that would include people of additional races and locations.