American Medical Association says use of BMI metric on its own has done ‘historical harm’

The American Medical Association (AMA) said the use of the body mass index (BMI) metric on its own has done “historical harm” as an “imperfect measure” of bodily health.

The AMA said in a post on its website this week that BMI has been widely used because it is easy to measure and inexpensive while providing specific cutoff points for someone being considered overweight or obese. But it does not directly assess body fat, and the current classification system is misleading about the effects of body fat mass on mortality rates. 

A report from the AMA Council on Science and Public Health presented at the annual AMA meeting in Chicago states that comorbidities, lifestyle choices, gender, ethnicity, family history, the duration of time spent in certain BMI categories and the expected accumulation of body fat with age can majorly affect the interpretation of BMI data. 

It also states BMI is a problematic measure for diagnosing and treating patients with eating disorders because it does not include the entire range of abnormal disorders. 

“There are numerous concerns with the way BMI has been used to measure body fat and diagnose obesity, yet some physicians find it to be a helpful measure in certain scenarios,” former AMA president Jack Resneck Jr. said in the post. “It is important for physicians to understand the benefits and limitations of using BMI in clinical settings to determine the best care for their patients.” 

The report led the AMA House of Delegates to adopt a policy recognizing issues with BMI for its historical harm, use for “racist exclusion,” basis on previous generations of non-Hispanic white individuals and lack of gender and ethnicity considerations. 

The policy also notes significant limitations exist on using BMI in clinical settings, and it should be used along with other valid measures, such as body composition, waist circumference and genetic and metabolic factors. 

The AMA plans to support additional research on applying extended BMI percentiles and its connection to other measures, risk factors and health outcomes and efforts to educate medical professionals on issues with BMI and other ways to diagnose obesity. 

Lauren Smolar, a spokesperson for the National Eating Disorders Association, told Axois that BMI can lead to stigma for weight and prevent those who are experiencing an eating disorder from seeking the treatment they need.