You're Thin—and Too Fat

Too much body fat puts even normal-weight people at higher risk of heart disease.

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When it comes to avoiding heart disease, the standard advice is that we should stay in our healthy weight range. But here's a disheartening thought: Even at a normal weight, we might be obese.

Perhaps the safety zone should be a fat range instead. That's the suggestion of a study—being presented today at the American College of Cardiology meeting—that links so-called normal-weight obesity with risk factors like high blood cholesterol and metabolic syndrome. It's been known for a while that normal-weight people can have a higher-than-recommended percentage of body fat. A researcher in the U.K. calls these people "TOFIs," for "thin outside, fat inside." But this study found that despite falling within a healthy weight range for their height—a body mass index range of 18.5 to 24.9—more than 60 percent of study participants were too fat. (In other words, the men's body fat percentages exceeded 20 percent; the women's, 30 percent). And these folks were more likely to have risk factors for heart disease, hypertension, and diabetes. You can calculate your own BMI here.

"The results challenge the way we label obesity," says Francisco Lopez-Jimenez, a cardiologist at Mayo Clinic and lead investigator. We tend to use it as a synonym for excess body weight, when really, he says, it's better used as a synonym for excess body fat.

This doesn't mean you need to run out and get your body fat percentage tested (though my colleague Sarah Baldauf did, and lived to write about it). (Though if you really, really want to know whether you, too, are a TOFI, many gyms and medical practices offer the service. Read Sarah's piece for the ins and outs of different methods; not all are accurate.) Midsection circumference is another way to gauge your odds of developing heart disease; if your waist is more than 35 inches around for females and 40 inches for men, you may be at higher risk of heart problems. And, if you're getting a regular physical, you probably already know how your blood cholesterol, blood pressure, and blood sugar levels stack up.

Bottom line? We've got to exercise and work on our eating habits. Marisa Moore, a spokesperson for the American Dietetic Association and a registered dietitian, points out that physical activity and a healthier diet can improve not only your body fat percentage but all those markers that doctors use to determine heart disease risk. If you're already at a healthy weight, your doctor may not think to remind you of their importance. So I will.