During the Annual Meeting of the American Medical Association (AMA), the House of Delegates adopted a new policy to clarify the way body mass index (BMI) can be used as a measure in medicine. Under the new policy, the AMA recognizes issues with using BMI as a measurement for multiple reasons. As such, and due to significant limitations associated with the use of BMI in clinical settings, the AMA suggests that it be used in conjunction with other valid measures of risk, such as measurements of visceral body fat, body adiposity index, body composition, relative fat mass, waist circumference, and genetic/metabolic factors.
The AMA policy notes that BMI tends to be “significantly correlated with the amount of fat mass in the general population but loses predictability when applied on the individual level.” The AMA also took note of the differences among racial and ethnic groups, sexes, genders, and age-span, saying that those differences are important to consider when applying BMI as a measure of adiposity and that “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.” Additionally, BMI “should not be used as a sole criterion to deny appropriate insurance reimbursement.”
The updated policy came to be because of a report completed by the AMA Council on Science and Public Health which reviewed the problematic history with BMI and discussed potential alternatives. The report noted that “[n]umerous comorbidities, lifestyle issues, gender, ethnicities, medically significant familial-determined mortality effectors, duration of time one spends in certain BMI categories and the expected accumulation of fat with aging are likely to significantly affect interpretation of BMI data, particularly in regard to morbidity and mortality rates” and that the “use of BMI is problematic when used to diagnose and treat individuals with eating disorders because it does not capture the full range of abnormal eating disorders.”
The AMA also notes that using BMI in conjunction with waist circumference “may be a better way to predict weight-related risk” in adults. For adults, the AMA also suggested other tests to diagnose obesity and measure health risks, including using abdominal circumference data, skinfold measurements, waist-to-hip ratio, dual-energy x-ray absorptiometry (DXA) or hydrostatic weighing/underwater weighing. However, for children, there is “no good reference data for waist circumference,” and as such, BMI-for-age will likely remain the “gold standard” for now.
“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,” said AMA Immediate Past President Jack Resneck, Jr. M.D. “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.”