One can be too thin even if they eat normally because of a high metabolism. One can end up with anorexia (extreme low weight dangerously below normal) because of cancer, stress, or a number of other reasons. They medically call it anorexia if your weight drops too low & has to be treated medically. (I had that problem with the stress I went through when my Mother was dying of cancer). They could't understand that I didn't have the anorexia nervosa no body image issues & I wasn't restricting on purpose. I just couldn't eat because I felt so sick & every time I would eat & would feel sick, so I just didn't eat for so long I ended up in the hospital on IV nutrition.

This happened to me several times, so the obvious treatment they thought I needed was in an eating disorders treatment center.....so I met many others who were dealing with ED's both anorexia, bulimia, & overeating. Most of those people didn't start off with body image issues......many started off abused, or were effected by something like having an abortion or experiencing trauma's in their lives that they had no control over. ED, even though it feels that you have no control over it, is the one thing in life that we do have control over. Control over eating ends up being the one thing in life that can be controlled.

I have always been concerned about not eating so much that I would end up overweight like others in my family in the past. I let it go for a few years & ended up way overweight, then had to loose weight which turned into an extreme weight loss because my Mothers situation happened at that time.

Just having a concern about not wanting to be overweight doesn't mean anorexia either. All the mental issues that can bother a person can turn into body image, or there is the problem when someone does have Body Dismorphic D (where they see their body in a way that it isn't). There are a lot of things involved in an ED, but there are always other mental illness issues that are going on with it that also need to be treated.

You need to look at yourself, your reasons for your low weight & your past. I know I looked at myself & saw a walking skeleton, so I didn't see myself as fat when I was so thin, but my medical Dr had to take care of the physical anemia that I was going through that wasn't any different than someone with anorexia nervosa.

Hope this & all the other replies have helped you look at your situation & have a better understanding.