Body Mass Index Can Incorrectly Label Obese People As Unhealthy: Study

Obesity and being overweight are common health problems in society today. It’s estimated that more than two-thirds of American adults are overweight or obese, and this unfortunately increases the risk factors for other health problems such as high cholesterol, type 2 diabetes, hypertension, stroke, osteoarthritis, and coronary heart disease.

Body mass index (BMI) is a screening tool that helps determine if a person is obese, overweight, underweight, or at a healthy weight. Over the years, BMI has become an effective representation of a person’s health. A BMI reading between 25.0 and 29.9 signifies that the person is overweight, while obesity registers at 30.0 and higher.

That said, BMI is not a diagnostic tool, and a person’s health is not as simple as inputting their height and weight into a calculator. In fact, in a new study published in the International Journal of Obesity, UCLA psychologists have found that using BMI to gauge health has falsely labeled over 54 million people in the U.S. as “unhealthy.”

BMI is not a great indictor of health because there are many other factors for health professionals to evaluate, including diet history, body fat percentage, family history, and exercise patterns. BMI also doesn’t consider gender, age, or muscle mass, and as a result, muscular athletes end up with a high BMI, but without a high body fat percentage.

Yet many American companies use BMI as a factor to help determine healthcare costs for employees—those with a high BMI may have to pay higher insurance premiums if a proposal from the Equal Employment Opportunity Commission is adopted.

For the study, the research team analyzed the link between BMI and various health markers like glucose, blood pressure, triglycerides, and cholesterol levels, using the National Health and Nutrition Examination Survey’s most recent data. The researchers found that 34.4 million people considered “overweight” because of a high BMI were actually healthy; the same applied to 19.8 million “obese” individuals and over two million people classified as “very obese” (with a BMI of 35 or more). The study’s lead author, A. Janet Tomiyama, assistant professor of psychology at UCLA, stated that when taking the health measurements (other than BMI) of these individuals into consideration, it is unlikely that they will have higher medical expenses, therefore it is unfair to charge them greater healthcare premiums.

The researchers also found that over 30% of those with “normal” BMIs (between 18.5 and 24.9) are actually not healthy based on other data. “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,” explained Tomiyama. “Employers, policy makers, and insurance companies should focus on actual health markers.”

The study’s co-author Jeffrey Hunger also believes that BMI is not a good measure of a person’s health. He recommends people focus on regular exercise and a healthy diet rather their BMI and weight. “This should be the final nail in the coffin for BMI,” said Hunger.

The next challenge for the research team will be to study people who are considered very healthy but have high BMIs.

Sources for Today’s Article:
Tomiyama, A.J., et al., “Misclassification of cardiometabolic health when using body mass index categories in NHANES 2005–2012,” International Journal of Obesity, 2016; doi: 10.1038/ijo.2016.17.