Even if your body mass index says you're of normal weight, you may still be carrying too much fat, according to new research.

A Mayo Clinic report says that more than half of people in the normal weight category have high body fat. That's more than 20 percent for men and 30 percent for women. They also show heart and other problems normally associated with obesity.

Researchers described people with a good BMI and high body fat as having "normal weight obesity." They said the condition can lead to diseases such as type 2 diabetes.

A news release also said that Mayo studies in 2006 and 2007 suggested that looking at body fat might be a better predictor of heart disease because BMI can't show the difference between body fat and lean muscle.

"Combined, the data from our earlier work and the current study suggest it's time for a new measure of body fat as a risk factor of heart disease," says Dr. Francisco Lopez-Jimenez, a cardiologist.