You can see it if you watch any US documentary filmed before the late 70s that shows ordinary people in the street. They're much fitter, and exercise for weight loss wasn't really a thing yet; people didn't jog. That's not far enough back that everyone was a farmer or laborer; there were plenty of fairly sedentary office workers. They also weren't starving; it was a prosperous time. They were generally eating meat-and-potatoes diets with plenty of animals fats (I have a 1960s barbeque cookbook that tells you to put a pat of butter on pretty much everything). And obesity wasn't a problem.

And since we started letting the government tell us how to eat healthy, not only has obesity skyrocketed, but so have diseases connected with it.