Also I think an underrated aspect of fat people is the understanding that food is a chemical and like with any chemical, there is a chance (and some people or populations of people are more prone than others) to addiction. Especially with sugar.
So you have people who are getting cheap hits of dopamine from eating pleasurable and tasty foods, and over and over and over, they build a tolerance. So now they have to eat like crap all day long to get those highs. Or else the alternative is they feel like crap even when heating "healthy" so they think, why bother eating healthy when it makes me feel sick? So they relapse back to the stuff that is killing them. No different than heroin, at that point, directionally speaking.
As many can attest after a long boys weekend or a vacation of eating like crap-- you feel like crap and have a sort of hangover or detox period complete with headaches or lethargy or migraines-- now put yourself in a 260 lb, 6 foot or shorter person (and beyond) and you start to see the real problem is that once you've become food/sugar addicted, it takes a level of commitment and mental strength to break that cycle that isn't for everyone. And if you are an adult and say, "meh, i'll take the trade-off of feeling/looking like crap and a half dozen years of lifespan because I get to eat decadent foods at semi-leisure and on whim", then so be it.
Still, I'll die on the hill that if you are raising fat kids, you should be talked to about it-- whether it from a doctor or a social worker. Don't put your own unhealthiness and poor decisions and choices and food addictions on innocent kids, just like you wouldnt give them booze or cigarettes.