John. My heart goes out to you. May I suggest that you have some skepticism about the drugs are not the problem issue? Her symptoms are very consistent with cocaine or meth usage--weight loss, personality change, rarely eats, rarely sleeps. Perhaps further inquiry in this area is warranted. I believe there are tests using hair that can look at drug history over a several month period.
Not neccessarily. Especially at this age, girls tend to have issues with self-perception. My first year in college, there was a girl living down the hall who everyone knew was anorexic. Her parents would come visit regularly to try to make sure she was eating, sometimes taking her out to one of the local places to have lunch together or something. I've also seen a few of that type at the campus gym. There're plenty of social pressures to look trim and it can lead to eating disorders. I guess the other questions I would have is how her grades are, and has she made friends?
Excellent advice. Physiological causes must be ruled out first and any responsible therapist engaged for this disorder will do so first and foremost.
Very true, it may not be anorexia... sadly drugs are very real and prevalent today.