Actually, I think the fact that the US just recently (in the great schemem of things) went from an almost completely agrarian society to an urban one has a lot to do with our portion sizes.
I have relatives who are farmers, and they eat large portions of food, with 3 meals a day. They also work harder before lunch in a typical day than I do in a typical weekend. They burn off all the calories, and so actually need to eat the portions they do.
But when I get home from visiting them, I find that I'm still eating those huge portions - it's just that I don't really need to eat that much because I'm so inactive in comparison.
So I'd say that in the US, people still eat like farmers: even in the big city.
I have relatives who are farmers, and they eat large portions of food, with 3 meals a day. They also work harder before lunch in a typical day than I do in a typical weekend. They burn off all the calories, and so actually need to eat the portions they do.
But when I get home from visiting them, I find that I'm still eating those huge portions - it's just that I don't really need to eat that much because I'm so inactive in comparison.
So I'd say that in the US, people still eat like farmers: even in the big city.