I would be worried about her as well. I was bulemic for many years , then began to switch into anorexic behavior as well. Luckily I stopped all of that on my own, I'm not sure how, but I did. But fast forward to years later and after two devastating divorces, I went the opposite way and began overeating. Ugh. I would talk with her about your concerns and reach out to her. I really hope she will be OK. I think she needs at least a friend to talk to, but perhaps a therapist as well if she has the insurance to cover it. Bottom line is, it needs to be dealt with sooner rather than later, before it gets to be more and more of a problem in her life. She is very lucky to have such a concerned friend in you. I hope everything gets better for her.