Re weight trends, was 20 years ago that we visited Prague for our silver wedding, and I well remember an American visitor wondering how on earth the locals were so slim, when most of the food we were offered everywhere was meat/potatoes/dumplings - very little in the way of veg or salad.
Answer, presumably because there was virtually no fast food available, people were cooking from scratch, and very few had cars, so plenty of walking.
Exactly the same in the U.K. I think, only our transition to a nation of fatties happned rather earlier.