A large, community-based study--considered the first to assess the long-term risk of developing overweight and obesity in U.S. adults--found that over 30 years, 9 out of 10 men and 7 out of 10 women were overweight or became overweight. In addition, more than 1 in 3 of those in the study were obese or became obese.

"National surveys and other studies have told us that the United States has a major weight problem, but this study suggests that we could have an even more serious degree of overweight and obesity over the next few decades," says Elizabeth G. Nabel, M.D., director of the National Heart, Lung, and Blood Institute (NHLBI).

Researchers analyzed the short-term and long-term chances of developing overweight and obesity among more than 4,000 white adults enrolled in the offspring cohort of NHLBI's Framingham Heart Study, an ongoing study in Framingham, Mass. Participants ages 30 to 59 were followed for 30 years, from 1971 to 2001.

Nabel, who also co-chairs the Obesity Research Task Force at the National Institutes of Health, says that because the research looked only at whites, "these results may underestimate the risk for some ethnic groups."

Other studies have shown, for example, that Hispanic and black individuals, especially women, have a greater prevalence of excess weight compared with their white counterparts.

The Framingham researchers assessed the participants' body mass index (BMI)--a standard measure of weight relative to height, which is an indicator of total body fat. A BMI of 18.5 to 24.9 is considered a normal, or healthy, weight for adults. A BMI of 25 to 29.9 is considered to be overweight, and obesity is a BMI of 30 or higher.

Making it to middle age without extra pounds was no guarantee for staying at a healthy weight--even in the short term. About 1 in 5 women and 1 in 4 men who were at a healthy BMI at a routine Framingham study examination became overweight after four years. Among those who were overweight, 16 percent to 23 percent of women and 12 percent to 13 percent of men became obese within four years.

"Our results, although not surprising, are worrisome," says Ramachandran Vasan, M.D., associate professor of medicine at Boston University's School of Medicine and lead author of the study. "If the trend continues, our country will continue to face substantial health problems related to excess weight."

According to the National Center for Health Statistics, part of the Centers for Disease Control and Prevention, 65 percent of U.S. adults ages 20 years and older are either overweight or obese, and about 30 percent of adults are obese.

"Overweight and obesity increase the risk of poor health," says Nabel. "We hope these results will serve as a wake-up call to Americans of all ages. Even those who are now at a healthy weight need to be careful about maintaining energy balance to avoid gaining weight. Taking simple steps to make sure that the overall number of calories you consume do not exceed the amount you burn can play a major role in lowering your risk for many chronic conditions."

Being overweight increases the likelihood of developing diabetes, high blood pressure and heart disease, stroke, breathing problems such as asthma and sleep apnea, some cancers, osteoarthritis, and gall bladder disease. Obesity is associated with these conditions as well as with early death. Research has shown that even a small weight loss--10 percent of body weight--can help people who are overweight or obese lower their risk of developing many of these conditions.

For help assessing obesity risk and advice on how to lose weight, consult your health care professional.

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