Ethicist: Should ‘Body Roundness Index’ Replace Flawed BMI?

This transcript has been edited for clarity.
Hi. I’m Art Caplan. I’m at the Division of Medical Ethics at New York University Grossman School of Medicine.
Who among you know your body mass index (BMI)? The BMI has been used for a very long time to measure obesity. According to the BMI, huge numbers of Americans, and indeed people all over the world, are obese.
It’s a medical screening tool that often comes up at a physical, and it’s widely used and has been for many years, but it is deeply flawed. It doesn’t really account for racial, ethnic, gender, or age diversity. It was norm scaled, if you will, many years ago, according to a small sample of White men in the armed services.
One of the big gripes about it is it doesn’t really do a good job differentiating between muscle weight and fat weight. Arnold Schwarzenegger, when he was a young man and a bodybuilder, had a 32-inch waist, but the BMI made him absolutely obese given the amount of weight he was carrying that was muscle weight.
With all these problems of scale of the BMI, a new scale or measure has been proposed, called the body roundness index (BRI). Many experts in obesity, metabolism, and diabetes believe that this is a much better indicator of health issues due to weight. It’s a measure of how round you are, literally, around your stomach.
It doesn’t really pay too much attention to your height vs weight. It really is watching body fat on the waist. The rounder you are with abdominal fat, it looks like the more danger is posed to your health and long-term mortality. This BRI has been scaled on many groups, and its predictive abilities seem much better than the BMI’s.
A paper just published in JAMA Network Open showed that, in addition to many prior studies, it’s a very good predictor, sadly, of mortality. The rounder you are in the gut, the more trouble you have. Fat stored in the legs and sometimes in the buttocks doesn’t seem to have the same health issues as those associated with abdominal fat.
When you’re talking to people about weight, it is time, I think, to start to shift away from the BMI. I’m not arguing that it isn’t important to get on a scale and see what your weight is overall, but where that weight is and how it’s distributed in your body, experts are starting to understand, is really the issue that ought to be most concerning.
The rounder that gut, the more there is going to be an issue that the patient needs to pay attention to in terms of weight. I think it’s time to say goodbye to the BMI and hello to the BRI, a much more accurate, more representative, and more predictive index of concern about weight and obesity.
I’m Art Caplan at the Division of Medical Ethics at NYU Grossman School of Medicine. Thanks for watching.