"The whole thing perpetuates itself," another woman says. "You're surrounded by girls and guys who are so concerned about dieting. It's almost a competitive thing among a lot of girls."

Ironically, the very attempt to achieve control over eating habits only plunges the victim deeper into the uncontrollable cycles of abnormal eating behavior.

Clinical manuals characterize anorexia nervosa as "a phobic avoidance of food" in the presence of a loss of about 15 percent of one's body weight. Bulimia, on the other hand, is associated with the cycle of uncontrolled eating ("binging") and subsequent ridding of the body of unwanted food ("purging").

And self-gagging and vomiting are not the only means of purging, the bulimarexic student says. Ipecac, a drug used to induce vomiting, and laxatives are frequently used, resulting in serious chemical imbalances and heart problems, she says.

"Laxatives are so dangerous. They don't even rid your body of food...they rid your body of everything it needs to stay alive, like electrolytes. It gives a very temporary feeling of being skinny, because you're really just dehydrated," she says. "And after using [ipecac] for so long, it really poisons your body."

"Controlling means complete lack of control," the same student says. "With bulimia, when you try to control, you basically set yourself up for a binge. And with anorexia you're not in control of anything either...You can't think clearly because you're at such a low weight."

While the bulimic cycle often begins with extreme dieting, a subtler form of the purge, the cycle may also be driven by the binge due to the interplay between "the effort to seek control and the effort to seek some comfort," says Riendl.

"For people with eating disorders, it is the combination of the desire to seek some sense of control and the over-reliance on food that is a set-up for a binge-starve cycle that can lead to a binge-purge cycle," she says.

Aside from the physical aspect of the cycle, a variety of psychological cycles perpetuate the problems. In some eating disorders, perfectionism breeds perfectionism, according to Hall.

"When you starve yourself, you begin to think in very concrete black and white terms which only encourage perfectionist tendencies," Hall says. "Then you can't deal with anything that might be perceived as failure."

The feeling of being thrust suddenly into independence can be traumatic, especially for college students. One student says that being sick allowed her to continue to rely on her parents.

"It's that idea of staying like a little kid. Being sick was a way for my parents to take care of me still," she says. "And my parents really fed into that. It became a way of not dealing with social situations."

After a while, the eating disorder became a part of her identity, the woman says. "It was expected of me and I felt obligated to stay in that role," she says.

Hall says the physical and psychological cycles are both unhealthy and difficult to break.

The slight rise in eating disorders at Harvard may be explained by the overwhelming diet mentality of our time, Heatherton says.