Has the Obsolescence of BMI for Screening Been Overstated?
It is really easy to beat up on the lowly BMI. The Lancet Commission on clinical obesity gently kicked it to the curb by saying BMI “can both overestimate and underestimate adiposity” and thus declared its obsolescence as a singular measure for excess adiposity.
“Excess adiposity should be confirmed by either direct measurement of body fat, where available, or at least one anthropometric criterion (eg, waist circumference, waist-to-hip ratio, or waist-to-height ratio) in addition to BMI.”
But is this really necessary?
A new research letter in JAMA says maybe not.
98% Concordance
The letter, by Ebenezer Aryee and colleagues, documents good accuracy for BMI alone. In 98% of patients, BMI alone is accurate for identifying excess adiposity as compared to BMI confirmed with a second measure as recommended by the Lancet Commission. They write:
“Although certain patient populations (eg, athletes) may warrant further evaluation, our results suggest that these individuals make up a very small portion of the population. For nearly all US adults with elevated BMI, there may be limited utility to confirming excess adiposity.”
Questions Welcome
Not for a minute do we dismiss the recommendation of the Lancet Commission to look beyond BMI for understanding the clinical status of someone with obesity. Questions about conventional wisdom should always be welcome. But we are not ready to embrace the supposed obsolescence of BMI.
Likewise, we see no problem with people debating the potential effects of the Lancet Commission distinguishing two states of obesity: clinical and preclinical. People we respect have concerns that people with preclinical obesity will see their access to care limited by health systems seeking to save money.
As with BMI, we understand the concerns about setting a line between clinical and preclinical obesity. But we suspect that those concerns are a bit overstated. The debate will continue and greater clarity will surely come from it.
Click here for the new research letter, here and here for further reporting on it.
Coiled Tape Measure, photograph by D. Sharon Pruitt, licensed under CC BY 2.0
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April 21, 2025
