Saying "balanced diets are good for the body" isn't discriminating towards people with eating disorders any more than saying "people need sleep" is discriminatory towards people with insomnia, mania, nightmares, etc. A more extreme version would be saying that saying "self harm isn't healthy" is unjust for people with BPD (highest rate of SH for any specific mental health d/o) It's just a fact that our physical bodies have physical needs to operate at their best.

I'm not trying to be harsh, but why do you care if others accept what you eat or not? Part of wanting an accepting society is being accepting even (especially) if others aren't.