@Ncfeminismboard - maybe @oldwomanwhoruns phrased it badly, but I get what she means. It wasn't intended (I'm sure) to minimise your experience, but in older generations eating disorders were a way to express how we felt we didn't fit in, weren't understood, were mistreated, get attention (even when we also hated the attention), were ignored and yes, absolutely in some ways to rebel... 'you can force me to eat this, but you can't force me to keep it inside me'.
I'm sure if I was that lonely teenager now and Googled 'I don't feel my family understands me, I don't feel like I fit in' etc and there was a whole community and ready-made peer group telling me that actually I was really a boy then I might well have jumped at the chance of being like my strong, sporty, much cleverer & better looking brother - especially if there had been no one to explain the nuances of how my body wouldn't actually magically become like that! I'm very glad I was a teen before the Internet existed and that I found a bunch of goth friends to 'fit in with' instead.
You're right though that eating disorders are serious and do have long reaching consequences. I think the huge difference is that if you go to the doctors they don't agree that 'yes you are really fat still and need to lose a few extra lbs, ignore what your parents tell you', whereas they do agree that 'yes you are really born in the wrong body, ignore what your parents tell you, have some nice puberty blockers and hormones and bind your breasts up, it'll be fine'.