Study Suggests Most in U.S. Will Be Fat 

A new study that followed 4,000 people for three decades suggests that over the long haul, 9 out of 10 men and 7 out of 10 women will become overweight.

Even those who made it to middle age without getting fat were not safe. Half of the men and women in the study who had made it well into adulthood without a weight problem ultimately became overweight. A third of those women and a quarter of the men became obese.

"You cannot become complacent, because you are at risk of becoming overweight," said Dr. Ramachandran Vasan, an associate professor of medicine at Boston University and the study's lead author.

Researchers studied data gathered from white adults over 30 years. Participants were ages 30 to 59 at the start, and were examined every four years. By the end of the study, more than one in three had become obese.

The study defined obesity as a body mass index, which is a commonly used height and weight comparison, of more than 30.

The findings, to be published today in The Annals of Internal Medicine, show that obesity may be a greater problem than indicated by studies that look at a cross-section of the population at one point in time. Those so-called snapshots of obesity have found that about 6 in 10 are overweight and about 1 in 3 are obese, Dr. Vasan said.

The findings also re-emphasize that people must continually watch their weight, Dr. Vasan said.

The subjects were the children of participants in the long-running Framingham Heart Study, which has been following the health of generations of Massachusetts residents.

Susan Bartlett, an assistant professor of medicine and an obesity researcher at the Johns Hopkins School of Medicine, said the study was one of the first to look at the risk of becoming overweight.

"The results are pretty sobering, really," said Dr. Bartlett, who was not involved in the research.

Obesity raises the risk of heart disease, some cancers, diabetes and arthritis, and being overweight raises blood pressure and cholesterol, which in turn can raise the risk of heart disease.

Mark W. Vander Weg, a psychologist at the Mayo Clinic who researches obesity but was not involved in the study, said it was one of a few to track a group of individuals over an extended period.

"What's particularly concerning is that these results actually may underestimate the risk of becoming overweight or obese among the general population" because minorities, who are at increased risk for obesity, were not included in the study, Dr. Vander Weg said.

While more studies are needed, Dr. Vander Weg said, the results "add to a growing body of evidence that makes it increasingly apparent that more effective prevention and treatment strategies are urgently needed."