My friend is a dietician and she said a lot of them have eating disorders too.
They are the last population to actually understand how overweight people think. I know of 2 who have said to me at different times, "I've been this same weight since high school". I thought, "then what do you even get about this?" It took me years to understand that they were saying "listen to me, I know because I'm not fat".
Meanwhile a lot of them are starving and purging themselves....they think entirely differently.
But it's all self-loathing nonetheless:(