Have you told her point blank that you are concerned she has developed an eating disorder? Sometimes it takes being very blunt and tell people in no uncertain terms what it appears to be. Good for you that you care enough to try to do something. If it's nothing it's nothing to get mad at you over... Just show you care. If she gets mad because you care... Well then you are probably very much onto something. Do her parents know?

Sent from the dark side of the moon