It's the calories that count for obesity, not the "healthiness". It's perfectly possible to maintain a healthy body weight eating chips and drinking soda. Time isn't a factor here, personal responsibility is.

Yes, I am on the same page that all you need is a bit of discipline (and some baseline amount of crucial nutrients not present in cheap calory sources). But we all have about the same "discipline reserve", and some have harder life circumstances that expend that reserve on more urgent things than lunch. And this snowballs after it happens once. But to be fair, I do not really know what is the percentage of "well-off cushy fat people without a modicum of health discipline" vs "money-poor and time-poor stressed depressed fat people". I do suspect the latter group is bigger, and just yapping about "personal responsibility" kinda misses the point in that case.

You don't need to be money-poor to be time-poor and stressed. Just as with other vices, it's a matter of priorities - do you prioritize your near-term comfort or your long-term wellbeing? People can make either choice, but I expect them to take responsibility for the outcome.