Demystifying BMI as a Tool in Healthcare and Litigation Matters; a 3-Part Series

Part 3: The latest research on BMI and how it can impact your legal case.

In Parts 1 and 2 of this 3-part series, we delved into the origins of Body Mass Index/BMI and the definitions of “fatness” as well as some of the associated drawbacks and potential health complications. I bet you were wondering, “If BMI is so imprecise, why have they been using it for so long?” That is what I was thinking. The best I can figure out is that in today’s politically correct society, it must be easier for a provider to discuss with their patient that their body mass index is elevated at 45 kg/m2 instead of telling them that they are “fat.” The good news (or bad depending how you look at it) is that there has been new research published suggesting alternatives to body mass index alone for diagnosing obesity.


On 06/14/23, delegates at the annual “Meeting of the American Medical Association (AMA) House of Delegates adopted policy aimed at clarifying how body mass index can be used as a measure in medicine. The new policy was part of the AMA Council on Science and Public Health report which evaluated the problematic history with BMI and explored alternatives. The report also outlined the harms and benefits of using BMI and pointed to BMI as an imperfect way to measure body fat in multiple groups given that it does not account for differences across race/ethnic groups, sexes, genders, and age-span. Given the report’s findings, the new policy supports AMA in educating physicians on the issues with the body mass index and alternative measures for diagnosing obesity.[1]


Under the newly adopted policy, the AMA recognizes issues with using body mass index as a measurement due to its historical harm, its use for racist exclusion, and because body mass index is based primarily on data collected from previous generations of non-Hispanic white populations. Due to significant limitations associated with the widespread use of BMI in clinical settings, the AMA suggests that it be used in conjunction with other valid measures of risk such as, but not limited to, measurements of visceral fat, body adiposity index, body composition, relative fat mass, waist circumference and genetic/metabolic factors. The policy noted that body mass index is significantly correlated with the amount of fat mass in the general population but loses predictability when applied on the individual level. The AMA also recognizes that relative body shape and composition differences across race/ethnic groups, sexes, genders, and age-span is essential to consider when applying BMI as a measure of adiposity and that BMI should not be used as a sole criterion to deny appropriate insurance reimbursement.”


In a research study published recently in JAMA Network Open, the authors examined data from 387,672 participants in the United Kingdom including body mass index, fat mass index, and waist-to-hip ratio. In conclusion, the researchers wrote, “Compared with BMI, [waist-to-hip ratio] had the strongest, most robust, and consistent association with all-cause mortality and was the only measurement unaffected by BMI. Current WHO recommendations for optimal BMI range are inaccurate across individuals with various body compositions and therefore suboptimal for clinical guidelines.”[2]


So what does this all mean for your legal client? If their height and weight alone puts them into the “overweight” or “obese” category utilizing the body mass index chart, there is some new research available to argue that BMI alone does not necessarily increase their risk for various medical complications and/or injuries. Additional research on this topic will likely emerge in the near future that will continue to support the flaws in the initial formulation developed by Lambert Adolphe Jacques Quetelet, the Belgium mathematician, in the mid-1800s.