Sam it is very hard on the friends and family you might want to talk to someone in the family first to see if she is already receiving some outpatient treatment u are not aware of. Then you will know better on how to address it. my friends used no tact at all and just ask me all the wrong questions that made me feel I needed to lie. I am sure her family has noticed the weight loss too, its hard to miss on a small framed girl. YOu may be the friend to save her life who knows.
Sam it is very very hard to come out of the life of anorexia but not as hard as it is to stay in it.