Is society too tolerant of fat people?

Maybe if we went back to ragging on them again we could get rid of this obesity epidemic that is taxing the hell out of our health care system and getting worse every year. Whats really so bad about having a social stigma against fat people? They chose to be that way or at least they didn't choose not to. Am I right? If we could get everyone to shape up this way then they would live longer and it would be worth the initial social pains they went through to get there wouldn't it?