AMA asks doctors to de-emphasize use of BMI in gauging health and obesity

CHICAGO — The American Medical Association on Tuesday strongly criticized the body mass index, urging doctors to de-emphasize its use in assessing health and obesity and acknowledging that the measurement has been used for “racist exclusion” and has caused “historical harm.”

The AMA, one of the largest medical groups in the U.S., voted to adopt this policy during its annual meeting here.

“BMI cutoffs are based primarily on data collected from previous generations of non-Hispanic White populations and does not consider a person’s gender or ethnicity,” the policy states.

The AMA doesn’t completely eschew the use of BMI, but says it should be used in conjunction with other measures such as body composition, waist circumference, and genetic factors. The policy additionally says BMI shouldn’t be used as a sole criterion for denying insurance reimbursement.

The group on Tuesday also amended a separate, existing policy on the treatment of obesity. Whereas the previous AMA policy only supported emphasizing that there are risk differences among age and ethnic groups at different levels of BMI and suggested waist circumference should be monitored for those with BMIs below 35, the amended policy takes a broader approach to monitoring obesity. It recommends educating doctors to look at other measures such as adiposity, body composition, and waist circumference in all patients and acknowledges that risks differ both between and within demographic groups.

BMI, calculated as weight divided by the square of height in metric measures, has long been used to identify health risks and classify whether a person has so-called healthy weight, overweight, or obesity. But mounting research has shown it’s not always accurate in predicting risk of disease on an individual level, and especially across different racial and ethnic groups.

The AMA’s view on weight and obesity has evolved over the years. It officially recognized obesity as a disease at its annual conference 10 years ago, and is now scrutinizing the use of BMI.

A subcommittee of the AMA wrote in a report leading up to the vote that BMI doesn’t differentiate between fat and lean mass and doesn’t account for body fat location. Studies have shown that fat that accumulates around the abdomen may be more dangerous than fat that gathers in the legs and thighs, hence why waist circumference or the waist-to-hip ratio could be useful measurements.

Additionally, BMI cutoffs don’t appropriately represent risks across racial groups, the subcommittee wrote. For example studies have shown that Asian, Hispanic and Black people have a higher risk of developing type 2 diabetes at lower BMIs than white people.

The report also noted that BMI is not a good way of capturing people who have eating disorders and “utilizing BMI can lead to substandard treatment, typically due to the use of BMI by insurance companies to cover inpatient treatment.” People with larger bodies have long struggled against weight bias and insurance barriers when seeking eating disorder treatment.

The use of measures like BMI and weight have jumped back into the spotlight as new drugs that lead to significant weight loss such as Wegovy, Ozempic, and Mounjaro have exploded in popularity.

Doctors have raised concerns that these treatments don’t differentiate between fat and lean mass and lead people to lose both. Some biotechs are already racing to develop even newer drugs that they hope will offer the advantage of cutting fat mass while maintaining or increasing muscle mass.

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