hi snow, welcome to the board. I suggest that you confront your friend as soon as you can, although it's not like a life and death thing. Give your friend an unltimatum. Tell her you're worried about her and if she doesn't start eating you'll have to tell someone. Don't let her tak you out of it. Be strong and keep your head on straight. It might be scary for you to tell someone, even if she hates you for a few days, she'll realize what you did was best. Trust me, I've done it before. And please tell her that she should come to this board if she needs support!
Good luck, tell us what happens.

Rachel