Your asking that question suggests to me that you don't know the real definition of the word "poor".There's "south side of Chicago" poor and there's "East African" poor.I've seen them both...and they don't even remotely resemble each other.
What I remember from 50 years ago is ice cream, candy bars, cokes, buttered popcorn, rich three-layer chocolate cakes...
Yes,I remember that.But I also remember....3 channels of TV (rather than 200)...no PCs....mowing your own lawn.... baseball/softball in the park....(in other words,we were far more physically active back then).
"Your asking that question suggests to me that you don't know the real definition of the word "poor".
That would be an error. I've traveled over large areas of the world, and have seen real poverty. You are correct that Americans are not poor in comparison to many in, say, the Philippines, but they are poorer than their more affluent, and more slender, countrymen.
"(in other words,we were far more physically active back then)."
That misses my point. Back then I was more active, ate like a little pig, and was skinny as a broomstraw. When I took a shower, I had to run around to get wet, and tie a 2X4 across my butt to keep from getting sucked down the drain.
Suddenly, almost overnight, something changed, when I was 21. Suddenly I had to watch what I ate very carefully *and* get olympian quantities of exercise to avoid weight gain. I had to be *more* active than I was as a child, and eat like a hummingbird.
There's another factor there somewhere. It's not just overating and underexercising. If that were the only problem, a normal person with normal dietary habits getting a normal amound of exercise would be of normal weight. Instead, many people must exert heroic efforts, and that's not normal.