The above are pictures of immigrants. Some are quite overweight, some are middling, and the only person really SLENDER is the guy in the last photo.

Quickly adding on...

I think we may be overestimating the "obesity epidemic" or at least overestimating the number of slender people in the past. Because of this thread, I've been looking at paintings and photographs of people a century (or two or three) ago. While I don't see a lot of 300-pounders, I see a LOT of chubby people by about age 30. It seems like there's a similar number of thin compared to chubby middle-aged people then and now. And if we're lacking historical portraits of the morbidly obese, I would say that's as due to 1) the fact that portraits weren't commonplace, 2) the heavier you are, the less likely you WANT your portrait/photo taken (Renaissance era excluded).

Sure, I'll concede that we have MORE overweight people now. But I don't concede that most people (who weren't starving on the streets) a few centuries ago were generally SLENDER.