When it comes to heart health nothing is sure…Why is that? Well, many people believe that if they have a perfect weight, they don’t have to worry about heart problems. New research shows the opposite.

Mayo Clinic researchers discovered that excessive body fat is associated with early signals of heart disease, even in people whose weight is considered normal for their height. It is what Mayo cardiologist Francisco Lopez-Jimenez, MD, calls the syndrome “normal-weight obesity.”

“For years we’ve been using BMI to diagnose obesity, but the first question we had was, ‘Is it possible to be normal weight but have excess fat?’”

Body mass index is defined as a ratio of weight to height. Overweight is defined as a BMI of 25 or higher; normal weight is defined as a BMI between 18.5 and 24.9.

Mayo Clinic researchers analyzed data from the National Health and Nutrition Examination Survey and discovered that among 2,127 men and women of normal weight and BMI between 18.5 and 24.9, almost half had excess fat – 20 percent of total body composition for men and 30 percent for women.

The researchers also found that 13.6 percent of the normal weight obese individuals met the criteria for metabolic syndrome compared with 5.3 percent of those who had a normal weight without a high body fat content.

“Better than trying to do just an eyeball diagnosis, we probably need to measure body fat. If people do have high body fat, it means that they might have similar cardiovascular risks as obese patients,” Lopez-Jimenez says, according to the Los Angeles Times.

The results of the study are the more troubling as more than half of the Americans are overweight or obese. And with this study finding that even skinny people can be fat, this means that the percentage of people who have problems because their fat is surely higher than estimated.

Robert Eckel, MD, a past president of the American Heart Association and a professor or endocrinology at the University of Colorado contradicted the results of the study saying, “Waist circumference, not percent body fat, should be in the mix. If a woman has 20% body fat and it’s in the pelvis, she’s probably not at increased risk [of heart disease]. But if it’s around the waist, she probably is.”

The results were revealed during the American College of Cardiology’s 57th Annual Scientific Session.