"There were times when for hours I would go back and forth from the kitchen [to the bathroom]," she says. "I would have a bowl of cereal and then go throw up, then go have a bagel and go throw up."

Binging and purging, however, had serious physical consequences.

"I lost enamel on my teeth. My fingers were raw all the time," she says. "My eyes were bloody, you lose definition of the chin, you get chipmunk cheeks. I had terrible stomach problems."

Things got better at first with the new freedom Lena found at college. During the second half of her first year, however, things got worse again.

And having friends at school who have similar problems doesn't help, she says. "I have a crazy group of friends. They are just insane about eating, insane about working out."

Lena was in therapy for half of high school, but no one ever tried to stop her bulimic behavior, she says. The thing that seems to have helped her most was a summer spent living and working in New York City.

She does not consider herself recovered and occasionally purges, but says she recognizes it is an enormous accomplishment to eat when she is hungry and to stop when she is full.

"The only thing that helps is if you lose interest in doing it," she says. "I feel a stronger sense of self."

Anorexia Nervosa

Anorexia is the other common clinical eating disorder, though it is not so prevalent among college-aged students as bulimia. While bulimic behavior commonly begins in the late teens or twenties, anorexia usually sets in earlier, at ages 12 to 13 or age 17.

"Anorexia usually starts younger," Heatherton says. "It's prognosis is usually more severe."

One percent of teenage girls nationwide develop anorexia, and as many as 10 percent may die from the disorder, according to the American Anorexia / Bulimia Association.

The disease is characterized by rapid loss of 15 percent of body weight, loss of menstrual cycle in women for three consecutive months, intense fear of weight gain, and highly distorted body image.

For one Harvard senior, the disease began in junior high school.

Elizabeth moved around a lot growing up both in the United States and abroad, and was also heavily involved with "figure-oriented" sports such as track and gymnastics.