Is it possible to have an eating disorder and not be underweight? Read details, please.

I don’t mean something like binge-eating-disorder. I mean an under-eating disorder.
I know that “anorexia nervosa” has weight requirements for a diagnosis, but are there other eating disorders that don’t?

I have a body image disorder that is very prevalent in people who also have eating disorders, and in the last few weeks I think that I am slowly coming to accept that I may be in that category. The problem is that I am not underweight. In fact, I could stand to lose 30–40 pounds. Realistically, according to actual numbers, not based on my own warped view of myself.

My problem is that I am unable to “diet” or “live healthier” without starving myself. I spent at least a year of my life refusing to consume more than 800 calories a day, while simultaneously running 5 times a week and working out on top of that. I did lose weight, but I have never been underweight in my life. I can’t snap out of that. As soon as I shift any type of focus on my eating habits, I default to starvation, I don’t know how to eat well without starving myself. Sometimes I go days without eating, and I have very negative associations with food and control issues. When I am not starving myself, I gain weight. When I am not starving myself, I also abuse laxatives and diuretics. Is it possible that decades of severe dieting has just trashed the shit out of my metabolism?

Are eating disorders about the physical effects on the body, or about our feelings and habits surrounding food? Can a person who is clinically overweight have an undereating disorder?

Why are overeating disorders not treated the same way as undereating disorders? Why does society scorn the obese or overweight as making dangerous lifestyle “choices,” rather than approaching overeating just the same as dangerous undereating compulsions?

Please note: I’m not asking you for a diagnosis. I’m just looking for general information and discussion on this topic. There are about 100 things that I need to see a therapist for, but I’m not ready to go back to that, so recommending that and bailing on the question isn’t helpful. I’m putting this in social because I’d like the discussion to have some freedom for opinions and anecdotes, but I am not seeking medical advice.