BMI Measurements Mislead Millions of Americans

Do you cringe when your doctor brings up your BMI? A new study could be your vindication.

The UCLA study, published in the International Journal of Obesity, cited that 54 million Americans were unfairly labeled as overweight or obese due to the limitations of using body mass index to judge a person’s health.

BMI is computed by dividing a person’s weight in kilograms by the square of the person’s heights in meters.

The Centers for Disease Control and Prevention (CDC) acknowledges that a healthy BMI is 18.5 to 24.9, overweight BMI is 25-29.9, while an obese BMI clocks in at 30 or higher. This equation, over weight alone, is preferred by many medical professionals to track and regulate health.

After examining more than 40,000 people, Janet Tomiyama, lead researcher in the study, found 47.4 percent of people with an “overweight” BMI and 29 percent of “obese” people were in good health. Markers of good health that were examined included participants’ blood pressure, triglycerides, cholesterol, glucose, and insulin resistance, among other health factors.

Related: Bigger Bellies Linked to Bigger Heart Disease, Diabetes Risk

The reverse data was also true. Individuals with normal weights — over 30 percent of those in the study — were metabolically unhealthy.

“This should be a final nail in the coffin for BMI,” said Tomiyama, who is also a psychologist at UCLA. “Obesity is just a number based on BMI, and we think BMI is just a really crude and terrible indicator of someone’s health.”

When BMI is used as the sole indicator of good health, the study shows that it results in the misclassification of 74.9 million adults in America, both healthy and unhealthy.

“The reason I think people rely on BMI is because it’s easy; if you know someone’s weight and you know someone’s height, then out pops this magical number,” Tomiyama said. “But getting blood pressure is pretty easy too. It takes maybe 20 seconds if you have the machine. And so I really think focusing on better health markers like blood pressure is a better way to go about it.”

Related: Chronic Stress Linked to Higher Levels of Obesity