Study Warns Against Relying Solely on BMI to Determine Good Health

Researchers urge against solely relying on body mass index, which has mislabeled many Americans as “obese” and “overweight” when they are actually healthy.

Body mass index (BMI) has been mislabeling many Americans as “obese” and “overweight” when they are actually very much “healthy,” according to a new study in the International Journal of Obesity. The research by University of California, Los Angeles (UCLA) finds that BMI incorrectly categorizes nearly 54 million Americans as “obese” and “unhealthy” and the researchers urge companies and individuals to not rely solely on BMI to determine whether people are healthy or not.

BMI has long been seen as a strong measure of a person’s health. Many companies in United States even use their employees’ BMIs as a factor in determining the workers’ health care costs. And if a new rule proposed by the Equal Employment Opportunity Commission were to be adopted in April, people with higher BMIs would soon have to pay higher health insurance premiums.

“Many people see obesity as a death sentence,” A. Janet Tomiyama, PhD, an assistant professor of psychology at UCLA and the study’s lead author, said in a statement. “But the data show there are tens of millions of people who are overweight and obese and are perfectly healthy.”

The research was funded by the Hellman Fellows Fund and the findings are published in the International Journal of Obesity.

BMI—A Flawed Health Marker?

BMI is calculated by dividing a person’s weight in kilograms by the square of the person’s height in meters. The researchers studied the link between BMI and other health indicators such as blood pressure and glucose, cholesterol and triglyceride levels in adults more than 18 years old using data from the most recent National Health and Nutrition Examination Survey.

According to the Centers for Disease Control and Prevention, BMI between 18.5 and 24.9 is healthy; BMI between 25 and 29.9 is considered overweight; and BMI of 30 or higher is obese. However, the study revealed that almost half of the Americans, who are considered “overweight” and “obese” by virtue of the BMI indicator, are in fact, healthy.

Other findings of the research:

  • More than 30% of those with BMIs in the “normal” range—about 20.7 million people—are actually unhealthy based on their other health data.

  • More than 2 million people who are considered “very obese” by virtue of having a BMI of 35 or higher are actually healthy.

  • There is no clear connection between weight loss and health improvements related to hypertension, diabetes, and cholesterol and blood glucose levels.

To present a clearer picture, according to the BMI markings, approximately 34.4 million Americans are overweight and 19.8 million are obese. The study doesn’t say that everybody is healthy. The study provides evidence that a majority of these “overweight” and “obese” people are actually “healthy” and are being incorrectly treated as “unhealthy.”

If people are labeled unhealthy simply on the basis of BMI, then they might be incurring extra medical expenses and higher health care premiums, which would be unfair to them, according to Dr Tomiyama.

“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 said. “Employers, policy makers and insurance companies should focus on actual health markers.”