BS”D
No, someone with an eating disorder is NOT OTD any more that chalila, someone who has leukemia is OTD.
I don’t pretend to know the first thing about eating disorders but what I do know is that eating disorders are diseases which can strike the frummest Beis Frime (yes that is the name of a school) girl just as much as the girl who is struggling with emunah and hangs out at the pool hall rather than going to class at her modern school.