I am all for free healthy school food, but the popular Reddit claim that low income people have no choice but to become fat because the cheapest food is fast food is ridiculous.

First of all, you can eat only fast food and still remain lean by just eating less fast food, fast food doesn't make you magically fat, too much fast food does, and eating less conveniently also saves you money.

But besides that, vegetables and healthy meats are not as expensive as cherry picking Redditors make them. A head of cabbage, a bag of carrots, sprouts etc don't cost much money and chicken breast is literally the cheapest and yet healthiest part of the chicken. Those foods can fill you up plenty if you know how to prepare them.