Being overweight and being fat aren't the same thing either. Most anorexic people wouldn't describe themselves as anorexic. Of course there are levels of over and underweight which are relatively acceptable. I'm borderline overweight, and that's because there are decisions to make around leisure time, pleasure, finances etc - and of course they're mine to make. But the attempt to shoehorn science to fit a political objective (and we see plenty of it across all sorts of behaviours people don't want to change) is just like pro-anorexia sites. Fat people die more. Encourage them to stay fat if they can stop being, and you're helping them die younger.