ANN ARBOR—Many obese Americans may have much less heart disease risk than is widely believed and conversely, about one fourth of normal weight individuals could have a cluster of cardiovascular risk factors.

The new research from the University of Michigan School of Public Health and Albert Einstein counters the stereotype that all obese people are at risk for heart disease, and that all thin or normal weight people needn’t worry about heart disease, said MaryFran Sowers, professor of epidemiology in the U-M School of Public Health.

Sowers is the senior investigator on the study, which is available today at the Archives of Internal Medicine.

About half of overweight men and women and one-third of obese men and women in a national study were without cardiometabolic risk factors. Sowers and Dr. Rachel Wildman from Albert Einstein University found that a quarter of thin and normal weight men and women age 20 and over (approximately 16.3 million adults) showed two or more cardiovascular disease risk factors. They also found that a little over half of overweight adults (51.3 percent or 35.9 million adults) and a little under a third of obese adults (31.7 percent or 19.5 million people) had no cardiovascular risk clustering.

The study findings are significant on several levels. First, results are based on physical examinations conducted in more than 5,400 women and men in the National Health and Nutrition Examination Surveys 1999-2004. These men and women were selected to be representative of the entire U.S. population rather than a small local group, Sowers said.

“It’s important because the major message is that, in the last 10 years, we’ve really begun to appreciate how important obesity is in terms of health, especially cardiovascular health,” Sowers said. “But we may have created a stereotype that is really not quite appropriate for everyone?that all obese people are at risk for heart disease. We have identified, using national data, that this stereotype is not really true.”

Researchers found that in both obese and normal weight people with healthy heart risk factor profiles, key factors were thinner waists and a physically active lifestyle. It’s been well recognized for years, Sowers said, that people with thicker waists are more likely to have increased cardiovascular risk factors, and this appears to be true for normal weight and obese people.

The important takeaway, Sowers said, is that one size does not fit all with respect to the cardiovascular risks. “It’s very important that we recognize these subgroups because we can look at their characteristics, their genetics, their behavior and metabolism, and how their fat functions and use that information to help those individuals who do have these cardiovascular disease risk factors.”

Sowers’ co-authors include: Rachel Wildman, Aileen McGinn, Swapnil Rajpathak, and Judith Wylie-Rosett of the Department of Epidemiology and Population Health, Albert Einstein College of Medicine, Bronx, New York; Paul Muntner, Department of Community and Preventive Medicine, Mount Sinai School of Medicine, New York, New York; Kristi Reynolds, Research and Evaluation, Kaiser Permanente Southern California, Pasadena.

MaryFran Sowers