I don't know if I would say it's because we are "affluent". I see plenty of obese people driving cars and eating at McDonalds who are not "affluent". I think we are conditioned to overeating crappy foods. Having spent some time in Thailand opened my eyes to how our culture likes to eat crappy fatty foods. They don't eat any less over there. They eat all lean foods, including meat. They are all slender and so you don't have this culture of excuses and self-deprecating jokes about being fat. My wife works in the health insurance industry and they are working on programs to make people see what their cost is to our system. Also, we have screening at work so if our BP and Cholesterol is below a certain point, we get a price break.
What other physical attributes are deserving of bullying?