I've definitely come across this association between transness and anorexia before, and I think there's a bit more literature on it now than there was when I originally looked into it (maybe 8 years ago?). Anecdotally, it seems like there's a strong overlap, too, but obviously anecdotes != population data.

Wrt OCD potentially manifesting as anorexia, I remember reading some theoretical stuff about the construct of compulsivity as a link between OCD, OCPD and EDs (and also Jennifer Traig's memoir, in which (iirc), she linked her experiences of OCD and anorexia via scrupulosity).

Also: orthorexia.