A new report rejects the nation that using the body mass index (BMI) to determine how healthy you are is faulty.

Workplace wellness programs that have been popping up have focused on having employees monitor their BMI as the main measuring stick for their health, and those with higher BMIs are often charged more for health insurance in line with the Affordable Care Act — but this may be incorrect, according to a Minnesota Daily report.

A study out of the University of California-Los Angeles found that 20.7 million people who had normal BMI measurements were actually unhealthy, and that those with high BMIs may actually be healthier than they seem.

BMI is using to compare weight to someone’s height, but the problem with this measurement is it doesn’t care where the weight comes from. Twenty pounds of muscle is the same as 20 pounds of fat when it comes to BMI. It also doesn’t take into account important factor age and gender, for example.

The study also found that 2 million peole who had high BMI measurements, making them technically very obese, were actually quite healthy.

BMI has long been criticized in the health community as an effective measurement of how healthy someone is, but this study puts some more solid evidence behind that criticism, and could result in changes down the road to the Affordable Care Act if it begins to gain traction.

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