It also finds that people who look great in a swimsuit can still be a heart attack waiting to happen.
The study found about half of overweight adults have mostly normal levels of blood pressure, cholesterol, blood fats called triglycerides and blood sugar. And almost one-third of adults considered obese are also in that healthy range. Together, that's about 56 million people.
The study's author says it's no secret that thin people can have heart-related problems and that fat people often do not. But the fact that millions defy the stereotypes may come as a surprise.
The results also add to mounting evidence that thick waists, even on people of normal weight, can be a signal of heart risks. The study appears in today's Archives of Internal Medicine.