The body mass index (BMI) of a person may be a flawed measurement of one’s risk of diabetes or heart disease, a new study suggests.

Based on the results, about 75 million people in the United States have a risk of diabetes or heart disease that is either higher or lower than their BMIs suggested it should be, the researchers found.

Jeffrey M. Hunger, co-author of the study and a doctoral candidate at the University of California, Santa Barbara, said that to stay healthy, people should focus on staying active, eating healthy foods, and getting enough sleep, rather than on their weight.

For the new study – published Thursday (Feb. 4) in the International Journal of Obesity – the researchers looked at data on the body mass index (BMI), blood pressure, cholesterol levels, blood sugar levels, insulin, and inflammation levels of about 40,000 adults in the United States.

Researchers stated that people are cardiometabolically healthy – which is the risk for diabetes and heart disease – when they have healthy values on at least four on the aforementioned indicators.

The results showed that about sixteen percent of very obese people, about twenty-nine percent of individuals with a body mass index in the obese range, and almost fifty percent of the people with a BMI in the overweight range were actually cardiometabolically healthy, according to the researchers.

Janet Tomiyama, lead author of the study and an assistant professor of psychology at the University of California, Los Angeles, said that the new data proves that there are a lot of people who are either overweight or obese and are perfectly healthy.

On the other end of the spectrum, the researchers found that more than thirty percent of the people, whose body mass indexes were in the normal weight range, were in fact cardiometabolically unhealthy.

A 2010 study, published in the International Journal of Obesity, also found that a person’s body mass index was not an accurate measurement of health. For instance, waist size was a better predicator of children’s risk of heart disease, rather than their body mass index.

In 2014, a study published in the journal Pediatric Obesity, found that twenty-five percent of children who were labelled as obese based on their body fat content, were not considered obese based on their body mass index.