I think it's societal acceptance in the south and Midwest. I've lived in both and been super active in both so it's not impossible to be thin. My ex in laws are almost all fat because that's how it's done (plus my ex mother in law apparently doesn't know how to cook anything healthy). When I was a kid many, many years ago, my mom was what I think would be considered a small fat today -- 5'5" and 225ish. I was pretty embarrassed by her and she's almost SLIM today (at 180ish) in comparison to the general population. I think people lost the ability to feel shame.