In reality, it's the final self-protective act, to destroy their bodies and their lives completely. Then they can truly escape the complexities of being alive.
The bulimic will binge grotesque amounts of food. She will assault herself with more food than her body can tolerate.
The compulsive overeater will, at last, have to stop eating if only because of the pain in her distended stomach. Her body sets a final limit. The bulimic has no such limit. She experiences (in her mind) no consequences of the food assault on her body. When her body cannot bear more, she will vomit it all out. Then she will resume her binge. She may reach her body's limits many times. Each time she does, she can throw up again and continue.
Eventually she stops, because she is completely exhausted, or she is in danger of being discovered. "Enough" has no meaning to her. There are no limits and no consequences for her disregard of her boundaries.
Realistically, of course, there are plenty of consequences. Her behavior inflicts serious damage to her body. And each time she attacks herself with a binge-and-purge episode, she destroys more of her spirit, soul, self-esteem, sanity, health, and value to herself and others.
Each violation deepens her ritualistic behavior, and she becomes more entrenched in her disorder. The consequence is increasing anguish and despair. Yet the eating disorder is not the cause of that anguish and despair. The eating disorder exists to numb her from her already existing psychological agonies.
For a while, maybe a few years, the eating disorder successfully blocks her awareness of pain too difficult to bear. But eventually the protective device of the eating disorder becomes just another boundary invader, this time self-induced, that weakens and damages her even more.
What do I mean by a history of boundary violations? Blatant and extreme boundary violations involve sexual molestation, sexual abuse, and physical abuse. Much has been written about these areas now, especially in material exploring Post Traumatic Stress Disorder (PTSD) and Dissociative Identity Disorder (DID).