As regards obesity the US might be out in front but many other countries are catching up fast. When I was a kid here in the UK large people were unusual, but now they're everywhere, albeit fewer in rich areas as it's certainly class-related. I don't see that there's any particular point to be made about the US and obesity other than that certain factors behind it are perhaps more exaggerated - in the US and everywhere else it's a function of class, cheapness, quality and availability of food, education, and to a degree also culture.