Episode Details

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Reader Shauna asked “I just saw an article about the Body Roundness Index, is that as silly as I think it is?”

The Body Roundness Index seems to be the weight loss industry’s response to finally having to (at least begin to) admit that the Body Mass Index (BMI) is nonsense. The BMI is a ratio of weight and height that has been used to pathologize bodies based on their size alone and has its basis in racism. I talked about that in depth in this piece.

Earlier this year the AMA, which takes hundreds of thousands of dollars in donations from the weight loss industry,  tried a little sleight of hand with this, admitting that there are serious issues with the BMI (which has been used as a justification for the much of the weight loss paradigm) but instead of acknowledging that simply pathologizing bodies based on shared size is an idea lacking scientific basis and merit that has done incredible harm, they instead said that we just needed more and different ways to pathologize bodies based on shared size.

That brings us to the study Shauna sent me: “Body Roundness Index and All-Cause Mortality Among US Adults” published in JAMA (the Journal of the American Medical Association.)

The authors reported no conflicts of interest, even though one of the authors, Qiushi Lin, MD, PhD, literally works for Sanofi Aventis which just had its weight loss drug preliminarily rejected by an FDA panel.

Where the BMI is used to pathologize bodies based on weight and height, the The Body Roundness Index (BRI) uses height and waist circumference.

The specific calculation they used is “364.2 − 365.5 × √(1 − [waist circumference in centimeters / 2π]2 / [0.5 × height in meters]2)”

The use of mathematical formulas tends to lend these concepts an heir of scientific validity that they do not deserve. They explain that “Due to the lack of a reference range, BRI was categorized into 5 groups according to the 20th, 40th, 60th, and 80th quantiles to explore the association with all-cause mortality.”

They find a “U-shaped association between BRI and all-cause mortality. Our findings provide compelling evidence for the application of BRI as a noninvasive and easy to obtain screening tool for estimation of mortality risk and identification of high-risk individuals, a novel concept that could be incorporated into public health practice pending consistent validation in other independent studies.”

By this they mean that those at the lower and higher ends of this scale have higher all-cause mortality. As I’ve talked about before, one of the cornerstones of research methods is that correlation does not imply causation. The U-shaped association they found might be a valid correlation. The mistake happens if the assumption is that the BRI is the REASON for the increased risk and, when it comes to weight and health (particularly those of higher-weight people) that’s what typically happens.

That’s what I think the problem is going to be. In our culture, there is a tendency to jump at any perceived “proof,” no matter how shoddy, that being higher weight causes health issues/is a health issue