Edit: Poor people in India are thin and rich are fat, quite opposite, again due to diet. Indian poor can't afford fast food in chain restaurants daily, must cook which is cheaper.
But you can also be so poor that you can afford calories, alcohol and little more as an entertainment. It's easy to get obese then.
On the other hand stuff like coca cola is cheaper.
You see, a fair amount of poor folks get paid once a month, and since there aren't a lot of little grocery stores nearby, folks wind up buying food once and hoping it lasts the month.
Poor folks don't always have steady electricity nor a refrigeration, either: Living without a fridge makes your diet go to crap pretty quickly.
Time is another luxury poor folks have issues with, which also makes diets go awry.
> Poor folks don't always have steady electricity nor a refrigeration, either: Living without a fridge makes your diet go to crap pretty quickly.
Differences between access to steady refrigeration is extremely slim for people in the US for all but the poorest of the poor (basically homeless)
> Time is another luxury poor folks have issues with, which also makes diets go awry.
In the US poor people have more free time, on average, than wealthy people: https://www.theatlantic.com/business/archive/2016/09/the-fre...
There are other studies that suggest the causality is the opposite: obese people are more likely to become poor: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5781054/
That study is definitely not broadly convincing in my opinion, but just want to point out that there is a ton of baseless speculation in this thread trying to explain the obesity/wealth relationship.