Body Mass Index (BMI), a seemingly simple health metric calculated by taking an individual’s weight, dividing it by their height, then squaring that number, has been the main metric to measure body fat since the 1970s.
It’s long been contested as flawed. It doesn’t for one, say anything about actual body fat—certain athletes, for instance, may register as obese due to muscle mass—nor does it account for fat distribution, a key factor in health risk associated with excess fat.
It is also racist.
Many in the medical community and beyond have decried the biased nature of the index for years, noting how it is used to pathologize bodies that don’t adhere to a white standard, and has become a tool of racism in society and health care.
On Jun. 13, the American Medical Association (AMA) finally acknowledged these issues, officially warning doctors to exercise caution in using BMI in medicine.
The racist origin of BMI
When Belgian mathematician Adolphe Quetelet developed the index in the 1830s, he did so using data from European white men, making it inherently racist and sexist. He intended it to be used for statistics at the population level and not for individuals, but it was introduced to medical diagnoses by physiologist Ancel Keys, and has contributed to the misdiagnosis of some people, especially of color, ever since.
In its note, the AMA recognized “issues with using BMI as a measurement due to its historical harm, its use for racist exclusion, and because BMI is based primarily on data collected from previous generations of non-Hispanic white populations.” And while it didn’t outright ask doctors to stop using the metric, it recommended it in conjunction with other measurements, including visceral fat measurements, waist circumference, and genetic/metabolic factors. Further, the association said, body shapes should be taken into account, in particular as they relate to ethnicity.
People with higher BMI pay for the misuse of this tool. The figure can be used to deny insurance coverage, for instance in fertility treatment, or for life insurance.
Yet the AMA came short of a recommendation that would have huge impact in the lives of the people misdiagnosed due to BMI biases. While it said the index should not be used by itself to deny insurance coverage, it did not recommend against using it at all, leaving the door open for unjust reimbursement denials.