Your mum is a dancer and restrictive eating has always been prevelant in Dance, modeling and acting circles it unfortunately goes with the job almost.
I'm sorry to hear that unkind and thoughtless remarks from her lead to your ed, sometimes those we look up to most can be thoughtless and unkind without meaning to and it is rotten that this should still be affecting you, have you thought about therapy to try and help you look at all this from another perspective?
Bottom line is your mum has been living and coping her own way for so long that you can't change things ( I know, my wife was actually bulemic when I met her but it was hidden from me, in 20 years we have only been able to talk about the issues once and that because of my daughters problems).
You can't change your mum, only she can do that, but you can look for help for yourself so this doen't follow you throughout your life.
All the best,