The reason: These eating disorder sufferers are male.

Long regarded as a women's problem, the trio of serious eating disorders -- the self-starvation of anorexia, the gorging and purging that characterize bulimia and the uncontrolled consumption of large amounts of food that is binge eating -- are increasingly affecting males.

Last month, Harvard researchers reported the results of the first national study of eating disorders in a population of nearly 3,000 adults and found that 25 percent of those with anorexia or bulimia and 40 percent of binge eaters were men.

The authors called the rate "surprisingly high" because earlier studies had estimated that males accounted for about 10 percent of the cases of bulimia and anorexia.

Although disordered eating is well-known among teenage girls and young women, experts say the problem among boys and young men is frequently overlooked by parents and coaches and under-treated by doctors. Males, they now believe, appear to be vulnerable to social pressures to achieve the perfect body similar to those that have long plagued women. But unlike the female ideal, which tends to focus on a "goal weight" or overall skinniness, men's focus is nearly always on achieving six-pack abs.

"Men are more reluctant to admit losing control" about food, said James I. Hudson, lead author of the study, which estimated that about 9 million Americans suffer from an eating disorder at some point in their lives. The research was published in the journal Biological Psychiatry.