BETHESDA, MD — The future burden of obesity-related conditions is likely to be substantial, researchers warn in what is considered the first study to assess the long-term risk of developing overweight and obesity in adults.

The large, community-based study found that over 30 years, nine out of 10 men and seven out of 10 women were overweight or became overweight. In addition, more than one in three were obese or became obese. Researchers analyzed the short-term and long-term chances of developing overweight and obesity among more than 4,000 white adults. Participants ages 30 to 59 were followed for 30 years, from 1971 to 2001. The results appear in the October 4, 2005, issue of the Annals of Internal Medicine.

"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," said NHLBI Director Elizabeth G. Nabel, M.D., who also co-chairs the National Institutes of Health (NIH) Obesity Research Task Force. "In addition, these results may underestimate the risk for some ethnic groups."

Framingham participants were white, and other studies have shown, for example, that Hispanic and black individuals, especially women, have a greater prevalence of excess weight compared to their white counterparts.

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

"Our results, although not surprising, are worrisome," comments Ramachandran Vasan, M.D., associate professor of Medicine at Boston University 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."