I'm currently reading a book on neurolinguistic programmation. It's really interesting. If this eating disorder is caused is stress induced, she can relieve hey anxiety with this strategy.
«A strategy for feeling anxious is to create a series of big, bright, close pictures of all the possible thigs that could go wrong. Looking at these pictures will make you feel bad. When you are anxious about someone who has stayed out late for example, you may experience a lot of bad feelings while vividly imagining everything that might have happened to them. Then you get angry with them,holding them responsible for the feelings. They may be very considerate, but you have created the pictures and the feelings, not them. Remember, we have wonderful creative mental powers and we can choose the feelings we create in ourselves.»
I thought it might apply to your problem.