The anorexic or bulimic reinacts the abuse symbolically with her body. The anorexic does not eat food (symbolic of an unwanted substance like a penis), and in this way regains the sense of control over her own body which she was not allowed in the rape situation. In the instance of the bulimic, sometimes a forced fellatio experience was either the most traumatic, most common, or only rape experience that she had, and in vomitting up her food, she symbolically pushes the unwanted substance out of her body. The fact that she gorges in the first place may be significant in that she perceives the abuse as something she asked for (a common belief of sexual abuse victims) which is, of course, untrue.
One will often hear girls with an ED, particularly anorexics, using keyword like "purity." This, again, probably has a connection with sexual molestation. The food is symbolic of sex, and in not allowing sex to corrupt ones body, or to purge the sexual tendencies from ones body, the victim regains their sense of purity, of innocence, which was stolen from them. It also serves as penance for sins which these victims did not in fact commit to begin with.
Becoming thin can also be an effort to get rid of secondary sexual characteristics such as breasts, hips, thighs, and buttocks, which signal sexual maturity. The sufferer attempts to return to their child-like body, because they feel that if not for these signs of femininity, they would not have been molested to begin with. The body becomes the enemy, the perceived sign that says "I'm a woman, rape me!"
Sometimes the issue is an intense and overwhelming self-hatred. This explains partially why eating disorders are primarily women's diseases. When something traumatic happens to a man, most often they take their anger and turn it outward, hurting others. Women are conditioned to be unaggressive, therefore they turn their anger inward, hurting themselves. This manifests itself not only in anorexia, but in cutting, burning and other such pain-inducing experiences. The body is the symbol, the shell, of ourselves, and to harm it obviously means we hate ourselves.
Some sufferers are so private and introverted that part of their motivation is simply the hopes of becoming smaller and smaller until they "disappear."
Sometimes the body is used as a canvas for self-expression. When no one notices, or chooses to ignore, the fact that the sufferer is in pain emotionally for whatever reason, and when she finds herself unable to verbalize her feelings, she attempts to use her body to tell a story. Starvation and cuts send out obvious, primal signals of pain. Your text book "cry for help."
I've often heard anorexia and bulimia described as slow suicide. The sufferer often says they were suicidal, but "didn't have the guts." Starving oneself or carving up their own flesh is saying "I want to die because I hurt so badly, but not yet. Right now I still have hope that someone will save me."
I address this to sufferer's: there are people who will help you get better. But you must save yourself, you must reach out to these people, who may be very close or very far (although they always feel very far, don't they?) Yes, you need someone to help you, to get your through this, and you can't do it alone. But you must first empower yourself to simply reach out your hand, and you may even have to find the strength in your to reach out over and over. Use that indomitable will, that incredible drive that you once used to hurt yourself, and now use it to reach out no matter how scary it might be. You had the strength to die, now have the strength to live.
If you feel you have no one to turn to, my email address is below. I offer you not only my friendship, but we'll find you resources within your area to get you some support. But first you must have the courage to cry out for help. There are those who will hear you.