According to a new study, many people who are listed as overweight as per their body mass index (BMI) scores may actually be classified as obese. “BMI along with the measures of the hormone leptin is a better way to measure obese people, especially those who are at increased risk of diabetes, heart disease and other conditions," says researcher Eric R. Braverman, MD, of Weill-Cornell Medical College in New York and Nirav R. Shah, MD, MPH, who is now the New York State Commissioner of Health. X-ray scans that measured the levels of body fat showed that 39% of the people who are classified as overweight actually fall under the obese category.
BMI is the measure of body fat based on the height and weight of the person, and is an indirect measure. According to this scale BMI score between 25 and 29.9 is classified as overweight while a score above 30 is considered as obese. Researchers feel that this indirect measure under-diagnose obesity and all the health issues related to it. In this study, the researchers analyzed the dual-energy X-ray absorptiometry (DXA) of more than 9,000 patients seen at a private practice. DXA measures muscle mass, bone density and body fat content of a person.
As per the BMI scores, 26% of the participants were classified as obese while according to DXA 64% were considered as obese. “This indirect measure is not accurate, especially in older women," says Braverman. Researchers suggest that a BMI score of 24 for women and 28 for men would be a better cut-off point for obesity. Although DXA is a more direct measure of obesity, many people may not be able to use it because of the cost.
A more accurate measure of obesity would be BMI and a blood test to measure the hormone, leptin, says Braverman. “Levels of leptin are correlated with fat content of the body and the levels usually range from 0 to 200 with the most optimal level below 5," he adds.
Weight loss surgeon Mitchell S. Roslin, MD, of Lenox Hill Hospital in New York City is still sceptical about the use of leptin levels as a measure of obesity. He does agree that BMI may not provide an accurate measure of obesity but leptin levels also may not provide a complete picture.