A new study finds that more than 50 million "quite healthy" Americans have been mislabeled as obese or overweight thanks to an over-reliance on BMI as a measurement of health, the Los Angeles Times reports.

“This should be a final nail in the coffin for BMI,” says A. Janet Tomiyama, lead author of a study published Thursday in the Journal of Obesity.

Tomiyama and her team looked at the blood pressure, glucose levels, cholesterol, and more of 40,420 people. They found 47.4% of people with an "overweight" BMI and 29% of "obese" people were actually healthy.

Conversely, more than 30 percent of people with a healthy BMI were surprisingly unhealthy. "Obesity is just a number based on BMI, and we think BMI is just a really crude and terrible indicator of someone’s health,” Tomiyama says. A recent proposal from the federal government would allow employers to charge employees who don't meet health criteria—including BMI—more for health insurance. Tomiyama says this would unfairly punish "overweight" individuals who are actually healthy, according to a press release. For example, NPR reports that not a single member of the Denver Broncos, who are obviously fit enough to play in the Super Bowl, has a "healthy" BMI. A coauthor of the study recommends people focus more on eating well and exercising regularly than strictly on weight. One expert argues BMI is still useful as a quick test to indicate health but should be followed with additional tests to determine a person's true health. (Your father's sperm might be making you obese.)

This article originally appeared on Newser: Millions of Obese Americans Are Actually 'Quite Healthy'

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