Honestly though, I don't think there's a big difference in the tolerance of overweight people between Europe and America, but there's a difference in how sensitive they are when it comes to the terms we use to define something that is or has been controversial(?).
For instance, where I live, a dark skinned person is usually referred to as a "neger", which literally is the same word as "n!gger" (it's even censored here). They both stem from "negro", I think. It's a normal, non-offensive word here, while if you call a dark person a "n!gger" in the US, people would be really offended because the world has a loaded history there. There are many politically correct words now to refer to dark skinned people in America. Same with "fat" people. Fat is only to be used in a humorous context it seems..? Otherwise, "fat" people are referred to as plus size, full figured, or even curvy...