Body mass index has been the obesity yardstick for decades. A study in the Annals of Internal Medicine, led by Brian P. Lee, MD, MAS, of Keck Medicine of USC, argues it’s failing about half the people it’s meant to protect.
“BMI is problematic because it does not specifically measure body fat and instead reflects total body weight, which includes muscle and bone,” Lee said. “So a muscular person can have a very high BMI but not have excess fat, while someone without much muscle can have a normal BMI but have excess fat causing health problems.” The clinical risk runs one direction in particular: “Many people assume that if their BMI says they are not obese, they don’t have to worry about the many health problems linked to obesity. Our findings show that millions of Americans may already have obesity-related health impacts and may be missing needed health interventions.”
Independent doctors put it more bluntly. “BMI measures weight. The others measure fat. They’re two different things,” said David Cutler, MD, a family medicine physician at Providence Saint John’s. Stanford surgery professor Dan Azagury, MD, agreed it’s imperfect but useful: “BMI is a useful and widely used screening tool for obesity because it is simple and easy to apply. However, it is not perfect for several reasons.”
Which is why it likely isn’t going anywhere yet. “While BMI fails to account for body composition, potentially categorizing muscular individuals as overweight, it will likely remain the standard until a more effective, simple calculation is established,” said bariatric surgeon Mir Ali, MD.
Joseph has been writing and editing for a wide variety of publications over the last decade. He loves covering news in the health and wellness space and has written extensively about all aspects of wellness for a wide range of publications.
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