BTW, I was 30 kg overweight. Then decided not to be anymore.
"Why did you work in a mine when you knew it could cause black lung?" - because I had to in order to bring money for my family. I have in very high esteem such people. As you say, you get the idea.
"Why did you willingly eat nasty stuff knowing what will happen, and you absolutely did not have to because you live in a country where you can get healthy (= normal, not some bio stuff) food?" - that's harder to explain. But still - this is a choice, we are free people, just do not come later stating that "you should understand, I have all these reasons not to be on time". Sorry, overweight, to get back to the main thread.
As an American person, I feel it is likely I have encountered at least as many fat people as you have, if not more, so appeals to your personal experience aren't that convincing.
As for your other ideas, by the time you're trying to sort out worthies you don't actually have a social state in any meaningful sense. You can find some fault with most people. "Why did you work in a mine when you knew it could cause black lung? Why did you spend so much time at the computer if you didn't want RSI? You wouldn't have rabies if you'd avoided rabid animals." You get the idea.