The obesity epidemic in the U.S. might be even worse than we thought. The primary tool used to diagnose obesity misses millions, leaving many people at risk of developing diseases like diabetes, heart disease and cancer. Doctors have long used Body Mass Index (BMI) to determine whether people have a healthy weight. BMI is calculated by dividing a person’s weight by the square of his or her height. A BMI of over 30 is classified as obese, and 25 to 29.9 as overweight. Using this technique, the Centers for Disease Control and Prevention found that over a third of U.S. adults were obese in 2010. However, a new study published in PLoS One says that by using better methods of assessing body fat, the actual number would be much higher. “When you use other methods, closer to 60 percent [of people] are obese. We call BMI the 'baloney mass index,'” study author Dr. Eric Braverman told CBS News. By reviewing medical records, researchers were able to compare BMI with another measurement of obesity called duel-energy x-ray absorptiometry (DXA). This uses x-rays to more accurately measure muscle, bone mass, and body fat. While BMI showed that 26% of the patients were obese, this jumped to 64% when using DXA. Also, 39% of the patients identified as not obese through BMI were found obese when using DXA. DXA scans, while more accurate, are impractical for frequent use due to their high cost. The researchers, however, point out that BMI could be enhanced by using it in conjunction with measurements of leptin, a hormone that regulates appetite and the body’s energy balance. They also suggest reclassifying the obesity cut-offs for BMI to 28 for men and 24 for women. Some doctors, however, are concerned that this would result in more people being misclassified as obese when they aren’t.
Using better tests of body fat than BMI would label millions more obese.