New York: Using body mass index (BMI) to gauge health is a wrong practice as it is a deeply flawed measure, reveals a study while adding that BMI should not be the primary goal for maintaining good health. BMI incorrectly labelled more than 30 percent of those with in the "normal" range -- about 20.7 million people -- as healthy whereas they were actually unhealthy based on their other health data, the study said. Also, more than two million people who are considered "very obese" by virtue of having a BMI of 35 or higher are actually healthy. That's about 15 percent who are classified as very obese. "The data shows there are tens of millions of people who are overweight and obese and are perfectly healthy," said A. Janet Tomiyama, assistant professor at University Of California, Los Angeles. There are people who are healthy and are penalized based on a faulty health measure, while the unhealthy ones of normal weight are flying under the radar of BMI, she added. The study recommends that people should focus on eating a healthy diet and exercise regularly, rather than obsess about their weight, and strongly opposes stigmatising people who are overweight, the researchers elucidated, in the study published online in the International Journal of Obesity. The scientists analysed the link between BMI -- which is calculated by dividing a person's weight in kilograms by the square of the person's height in meters -- and several health markers, including blood pressure and glucose, cholesterol and triglyceride levels, using data from the most recent National Health and Nutrition Examination Survey.