As I explained once before, this unhealthy relationship our hero has with food comes into play whenever she gets it into her head that she needs to go on yet another fad diet. Despite clear medical evidence to the contrary, the morose clod thinks that if she has to make a special meal for herself, everyone else should eat it too. No one on this Earth could possibly get it through Elly's thick skull that children shouldn't go on calorie-restricted diets unless advised to by a physician because she isn't a short-order cook put on this Earth to make a separate meal for herself and one for everyone else.
This, again, is a thoughtless repetition of the sort of behaviour that gave her the warped body image that she struggles with in the first place. She cannot bring herself to question her mother's methods no matter how badly they mess up her life because she's haunted by two self-defeating delusions. The first one is that she thinks that if she does what she thinks her parents expect of her, they'll admit that they should have treated her better. The second is her refusal to do anything that would make her life easier. She has a strong, unacknowledged need to make things as difficult as possible for herself because of the sad fact that the little voice that she believes is telling her to eat is actually telling her that she can't be allowed to enjoy life. It would be simpler, in a way, to make one meal for herself and one for her family; it would also be impossible because Mother wouldn't approve.