BOSTON — Frequent binge eating is the country's most common eating disorder, far outpacing the better-known diet problems of anorexia and bulimia, according to a national survey.

Psychiatric researchers at Harvard University Medical School and its affiliate, McLean Psychiatric Hospital, have billed the study as the first national census of eating disorders. The results were published today in the medical journal Biological Psychiatry.

The survey found that 3.5 percent of women and 2 percent of men suffer from binge eating, defined as bouts of uncontrolled eating, well past the point of being full, that occur at least twice a week.

The doctors diagnosed fewer than 1 percent of women and 0.3 percent of men with anorexia, a disorder where an exaggerated fear of weight gain causes undereating and malnourishment. The study determined that 1.5 percent of women and 0.5 percent of men had bulimia, characterized by the "binge-purge" syndrome of overeating followed by vomiting.

McLean Hospital's Dr. Harrison Pope, an author of the study, said binge eaters face severe risk of obesity and related diseases like diabetes, heart disease, stroke and certain cancers.

A binge eater, for instance, might eat a full dinner, then a quart of ice cream for dessert, followed by a bag of chips, without being able to stop, Pope said.

"It's a little bit analogous to something you hear from an alcoholic, when they might say, 'Well, I wanted to have one drink,' and they've had 12 drinks and they're passed out on the floor," he said in a conference call with reporters. "Even though they feel full, even though they feel disgusting and guilty, they can't stop."

Dr. James I. Hudson, the study's lead author and a Harvard Medical School psychiatry professor, said binge eating deserves more recognition from health professionals.

"These results argue that binge eating is common. It's more common than both the other eating disorders combined and it's strongly associated with obesity," he said. "Taken together, these findings suggest that this is an eating disorder and should be treated as such."

Funding for the study came from several sources, including the National Institutes of Health, Eli Lilly & Co. and the Robert Wood Johnson Foundation. Hudson said the research team interviewed more than 9,000 people nationwide from 2001 to 2003 about their eating habits and psychological backgrounds. The study probably underestimates the actual number of those with eating disorders, he said, because people are often ashamed to acknowledge their abnormal eating habits.

The survey also found that people struggle longer with binge eating — symptoms persist for an average of about eight years compared to less than two years for anorexic patients, who are often young and may recover as they mature. Bulimics suffer without cure for an average of roughly eight years, according to the study.