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Your BMI is a Deeply Flawed Measure of Health, Say Scientists

Tim Boyer's picture
Focus on diet and exercise, but not your BMI

Your BMI may not be such a good indicator or your health, says a new study that warns labeling someone as overweight or obese based on their BMI is a deeply flawed measure of health that may unfairly cost many Americans more for their healthcare coverage than they should have to pay otherwise.


Did you know that literally millions of Americans are misdiagnosed as unhealthy based on their BMI number? A new study alerts patients that if you are one of the many considered overweight or obese, you should be concerned about the financial implications of what some scientists say is a deeply flawed measure of health.

According to a news release from UCLA, researchers have made a new discovery that questions the validity of using a patient’s BMI as a measure of how healthy or unhealthy he or she is. From the data gleaned in their latest study, the researchers state that the BMI is actually a deeply flawed measure of health, which has led to the misdiagnosing of patients that could as a result unfairly force them to eventually pay higher health insurance premiums.

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

The data referred to originates from the most recent National Health and Nutrition Examination Survey―a program of studies that combines interviews and physical examinations designed to assess the health and nutritional status of adults and children in the United States.

What the researchers did with the data is examine the numbers to determine what association there is between a person’s BMI and multiple health markers such as blood pressure and glucose, cholesterol and triglyceride levels.

What the researchers found was that that using the BMI to gauge health labels more than 54 million Americans as “unhealthy,” even though they are not! A similar point made earlier by Dr. Oz that people should be less concerned about their BMI and more concerned about their BQ.

Furthermore, the data also showed that:

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• More than 30 percent 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. That’s about 15 percent of Americans who are classified as very obese.

According to the news release, another important finding from earlier research performed by the lead author of the new study is that that there is no clear connection between weight loss and health improvements related to hypertension, diabetes, and cholesterol and blood glucose levels. The significance of this is that patients are often told that losing even just 5% of their baseline body weight can measurably improve their health such as in preventing their prediabetes from turning into type 2 diabetes.

The new study’s findings are published in the International Journal of Obesity with the concluding statement that an estimated 74,936, 678 U.S. adults are misclassified as being cardiometabolically unhealthy or cardiometabolically healthy based on using BMI as the primary indictor of health. And as such, the authors believe that policymakers should consider the unintended consequences of relying solely on BMI, and that researchers should seek to improve diagnostic tools related to weight and cardiometabolic health.

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

Other health experts who have seen the data concur that people should not focus on their BMI; but rather, should stop obsessing about their weight, and start focusing on eating a healthy diet and exercising regularly.


Misclassification of cardiometabolic health when using body mass index categories in NHANES 2005–2012International Journal of Obesity 4 Feb. 2016, A. J. Tomiyama et al.

UCLA Newsroom “Don’t use body mass index to determine whether people are healthy, UCLA-led study says



I agree the BMI is flawed for another reason. Someone who has a high amount of muscle mass and low body fat will register a high BMI, based upon his or her weight. This person could be in tip-top shape, yet they will be penalized with a less-than-ideal BMI number.