Having dealt with an eating disorder myself, I can tell you that an eating disorder is much like an addiction to alcohol or drugs. Until the person with the eating disorder wants help, there is nothing anyone else can do. And then sometimes when that person does want help, it is too late.
Eating disorders also involve control issues. Food intake and outake is often thought of as the only thing this person can control in his or her life.
It's such a scary, sad thing to go through and to watch loved ones go through. Luckily I caught myself pretty fast, but there are still days when I want to go back to my destructive behaviors. It seems to be a life long battle for me, but thankfully I have some other outlets that help (such as a good exercise program, healthy eating, etc.).
I, also, would hate for this thread to turn into something about how thin (or overweight) people look and our judgements on them.