Recovering Anorexic Friend?

My friend is currently in treatment and recovering from anorexia, however it is pretty bad. Anyways her parents know so it's not a matter of me telling a trusted adult or anything, but rather how I should act when she gets back. We are good friends, I'm not quite sure how good but I think pretty good. Anyways, is there anything that would be beneficial OR harmful? for instance, should I avoid talking about food? should i eat in front of her or avoid eating? what about asking her what she learned and asking her how she is? I'm sure everyone is bombarding her so I don't want to be nosy, I just want to be a good friend but haven't a clue how.