Obsession; in this case, not another form of flattery?

My friend tends to become very obsessed. And by obsessed, I mean talking, thinking, imagining, dreaming and making this one rockstar her everything. She did this with a band previously but now has gotten over it. She is rather large and not what the world today calls, "pretty, beautiful, hot etc.". What makes me rethink that is how we can't even communicate anymore. All we do is talk about him. All the jokes are from him. She's obsessed and wants to go to the country he's from and meet him. She has actually seen every "part" of his body. Every...single one. It's gross actually. She has dirty dreams of him and just overall; it's getting out of hand. She's always on the computer, has no other life except hanging with one other friend. She is just getting more unhealthy. She shows signs of depression, bi polar disorder, ADD, ADHD, and also has an eating disorder. She goes days without eating. It's sickening but I have no idea how to help. One friend brought it up, but she becomes hostile

Your firend is so self-conscious and uncomfortable i her own skin, besides maybe having mental disorders, that she focus all her attention on someone she knows is safe to 'like' and then becomes obsessed with them because there is no fear of rejection or hurt. She starves herself in an effort to look more like what the media tells her she should look like, and, in her mind, (maybe) increase her chances of getting with her obsession. She really needs help, and no matter how scared you are of her getting mad at you, you HAVE to tell someone!

She certainly has some issues and needs to solve her probelsm while she is young before it ruins her life. If she won't talk then maybe someone needs to talk to her parents. It is not healthy behaviour and she needs professional help.

I agree your friend has an obsessive tendency that needs to be addressed. You should first talk to her about it. You should tell someone too but you need to be careful what you say lest you lose a friend.

I think that you can pinpoint her problems without trying to diagnose her yourself. In order to diagnose someone with a personality disorder they need to be observed by a proffesional for at least 6 months. Plus there are other diagnosis that could be at play.

You should recommend counseling for your friend.