Your comments are bordering on fat-shaming, which I find completely unacceptable.
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.
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.
And comparing the volume of people in different countries, usually US or wealthy China vs. France (my country) or Italy or Japan.
The difference is striking. It doesn't come from the fact that Americans or wealthy Chinese have some physiological problem: they just eat TONS of food and drink pure sugar (last one is for the US).
One should not look for fancy explanations when the evidence is there: people are more and more obese because they eat shitty food and drink sugar.
And do not talk me about "the poors who cannot afford anything else". We have poverty in France as well, and these people are not horrifically obese.
Chronic obesity means chronic overeating. Except for the infinitesimal minority wich was obese 100 years ago as well because of the weird gene. When they become obese, they are programmed to be even more obese. Or "big boned".
And like with everything in life, willpower moves you ahead in most cases. There is one genius for every 100 hard working people (with willpower) and 100 slackers (in the same demographics).
I cut by 1/3 to 1/2 what I was eating. I eat the same things, just less. And more fruit, and almost no sugar. Was it hard? Yes, to a point. Was it excruciating? No - I was just salivating while looking at a nice cake and my brain decided to say "no".
I still have a hamburger from time to time (say, every two weeks). It is European size.
My kid made a cake, I had two parts (even if it was awful, way too sugary).
I bike to the office because I love it, and play sports again. Just because I WANT TO.