Mary (her story) found a way to protect herself as best she could from unavoidable and intolerable fear and pain. Her pain comes from more than the physical event.
Mary is emotionally incapable of tolerating the knowledge that her father can and will terrorize her at any time and that her mother will not or cannot protect her. The people she depends on for daily care-taking and protection are dangerous to her. She cannot bear to live with that knowledge, and so she finds a way to know as little as possible about her true situation.
If Mary can blot these painful experiences from her awareness she will be able to fearlessly love and trust her father. She can also depend on her mother to care for her, and she can experience herself living in a safe world.
This has more to do with overeating than many people realize. A child has few self-protective resources. If an inescapable, painful, fearsome or humiliating situation exists, creative, strong children can put themselves into a trance. In this way they can dull the horror of their experience.
Children can divide their minds into pieces so that they are not present as a whole person during extreme torment. Different fragments carry different parts of the experience so the children do not have to know or remember the episodes in their entirety. In this way they make their experience manageable.
Mary saved herself from having to tolerate through knowledge or memory what is intolerable. Later she finds that eating when intolerable feelings are rumbling in her psyche helps support her internal barriers to her emotions. The division between what she can bear and what she cannot can't be maintained only by her earliest methods. Being immersed in a television show is not reliable. Eating to a state of numbness is reliable and helps keep her intolerable internal eperience at bay. (For some people, not eating at all will accomplish the same goal.)
Lack of food to keep feelings away or needing to eat and therefore ending starvation that keeps feelings away both create terror and bewilderment. Recovery has more to do with building a sturdy psyche that can tolerate feelings than in controlling eating habits and food through diet and exercise.