Mayo cardiologist Francisco Lopez-Jimenez, MD, calls the syndrome "normal-weight obesity."
Doctors typically use body mass index (BMI), a ratio of weight to height, to determine if you're overweight and at risk for heart woes. Overweight is defined as a BMI of 25 or higher; normal weight is defined as a BMI between 18.5 and 24.9.
But Lopez-Jimenez says that measure falls short.
"There are more and more data showing that we need to go beyond BMI lowering," he tells WebMD.
Patients with excessive body fat, especially around the waistline, should be evaluated for heart disease and urged to eat right and exercise, Lopez-Jimenez says.
What's excessive? A body fat percentage of more than 20% for men and 30% for women, according to Lopez-Jimenez.
The findings were presented here at the American College of Cardiology's Annual Scientific Session.
Normal-Weight Obesity Linked to Heart Risk Factors
The study involved more than 2,000 men and women of normal weight.
A total of 61% of them had excessive body fat and thus were classified as suffering from normal-weight obesity.
Lopez-Jimenez says that many gyms have commercially available scales that calculate your body fat percentage in a matter of seconds.
"Sadly, it's easier to get body fat measured at the gym right now than at the clinic," he says.
"But I think that in the future, doctors will be forced to measure this," Lopez-Jimenez says.
Robert Eckel, MD, a past president of the American Heart Association and a professor of endocrinology at the University of Colorado, disagrees.
"Waist circumference, not percent body fat, should be in the mix. If a woman has 20% body fat and it's all in the pelvis, she's probably not at increased risk [of heart disease]. But if it's around the waist, she probably is," he tells WebMD.
Eckel also challenges the study's cutoff points. "Who is to say that more than 20% [body fat] for men, or 30% for women, is abnormal? That hasn't been established," he says.