Hi,
i haven't heard of blind anorexics or bullimics, but my personal opinion is that it is possible, weither the subject was born blind or not.
A blind person can't see her body, but can touch it, feel it and be disgusted by it, I think. Even if the blind doesn't know what fat and thin looks like, they know what it is and have heard about the thin thing. Anorexia and bullimia may be caused by deep emotionnal issues, with have nothing to do with what a subject sees.
Maybe i'm right, maybe i'm wrong, I just thought i'd share my thoughts since no one has replied to you here and it's been a while since you posted your message.
Anakind