BMI Is Poor Predictor of Health, Scientists Say

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A fixation with youth and beauty is not new for our culture. But our obsession with thinness is. We equate a slender frame and a low body mass index (BMI) with success, sex appeal, and health, and punish those who don’t—or can’t—have these qualities. Doctors all-too-frequently discriminate against overweight people, attributing all their patients’ problems to their body type and overlooking other issues. The stigma is real, it’s dangerous, and it’s irrational. New research published in the International Journal of Obesity shows that overweight and obese people are often just as healthy, and sometimes healthier, than people of "normal" weight.

BMI has become a shorthand for both body shape and health, despite protests from researchers. In addition to the social stigma and poor medical care, people with high BMIs can face real financial obstacles. Many U.S. businesses now offer employees bonuses for weight loss and lower BMIs. A proposal from the Equal Employment Opportunity Commission would, if enacted, allow insurance companies to charge more for people who are overweight or obese.

A. Janet Tomiyama, lead author of the new UCLA study published in the International Journal of Obesity, thinks this is ungrounded and unfair. In a press statement for the study she says, "Many people see obesity as a death sentence, but the data show there are tens of millions of people who are overweight and obese and are perfectly healthy."

"There are healthy people who could be penalized based on a faulty health measure, while the unhealthy people of normal weight will fly under the radar and won't get charged more for their health insurance," she continued. "Employers, policy makers and insurance companies should focus on actual health markers."

Tomiyama and her colleagues analyzed data from the National Health and Nutrition Examination Survey (NHANES), which took place from 2005 to 2012. They compared people’s BMI categories with blood pressure, cholesterol, insulin resistance, triglycerides, and blood sugar—actual health markers, in other words.

The results told an indisputable story. “Nearly half of overweight individuals, 29 percent of obese individuals, and even 16 percent of [extremely obese] individuals were metabolically healthy,” the authors wrote. “Moreover, over 30 percent of normal weight individuals were cardiometabolically unhealthy.”

The old way of thinking can hurt everyone. Just as overweight and obese people are assumed to be unhealthy, the reverse is true for those with lower BMIs. The signs of illness can be overlooked in those who fit our cultural ideas of what “health” looks like.

Speaking in the press statement, co-author Jeffrey Hunger said he was ready for change. "This should be the final nail in the coffin for BMI,” he concluded.