Why the BMI is Wrong
The widely-used BMI (Body Mass Index) scale is not reliable after all, according to a new study published in the International Journal of Obesity.
According to the study, some 54 million Americans who have been labelled as overweight or obese using the BMI are, in actuality, really healthy.
"In the overweight BMI category, 47 percent are perfectly healthy," notes researcher Jeffrey Hunger from the University of California, Santa Barbara as told by Science Alert. "So to be using BMI as a health proxy - particularly for everyone within that category - is simply incorrect. Our study should be the final nail in the coffin for BMI," Hunger adds.
To come up with the eye-opening conclusion, the researchers analyzed the most recent U.S. National Health and Nutrition Examination Survey to define the relationship between BMI -- computed by dividing a person's weight in kilograms by the square of their height in metres -- and some known health markers. Blood pressure, blood sugar and cholesterol were some of the cardiometabolic assessments the scientists determined.
What the scientists discovered after analyzing the subjects' data is that BMI does not accurately determine a person's health at both ends of the weight scale.
"Not only does BMI mislabel 54 million heavier individuals as unhealthy, it actually overlooks a large group of individuals considered to have a 'healthy' BMI who are actually unhealthy when you look at underlying clinical indicators," explains Hunger. "We used a fairly strict definition of health. You had to be at clinically healthy levels on four out of the five health indicators assessed," he furthers.
While the BMI scale has its own known shares of limitations, the measure is still widely used by several U.S. companies to determine the cost of their employee's health insurance.
"This should be a final nail in the coffin for BMI," says lead author A. Janet Tomiyama, a psychologist at UCLA, as cited by The LA Times.
The findings might also open discussion regarding the new rule proposed by the Equal Employment Opportunity Commission (EEOC) which may penalize people with BMIs higher than 25 by making them pay higher premiums.
"We need to move away from trying to find a single metric on which to penalise or incentivise people and instead focus on finding effective ways to improve behaviours known to have positive outcomes over time," Hunger notes.