Multiply that by 5 for a family, and you have over $100 a week.
I figure you have oatmeal, toast, or cereal and a banana for breakfast.
You have a plain homemade sandwich (peanut butter & jelly, egg salad, etc) and a piece of fruit for lunch.
Then you save the rest for dinner. You can buy bulk rice & beans to use for lots of meals. You can buy bulk hamburger and make tons of spaghetti and other meals.
You can buy a whole chicken for dinner, and then you can use the bones to make a good brother for the next day.
I think it would be hard for 1 person to live on $21 a day, but easier for a family of 5 to live on $100 a week.
However, a single person could always get together with others on food stamps and split purchases. Instead of buying a dozen eggs a week, they split it with another person.
Plus, there are lots of buy one get one free at the grocery store. If you always take advantage of that.
I forgot to add that poor kids in public school also get free lunch (and I think breakfast), so it would be really easy for a family of five to live on $100/week.
Try $70 a week:
http://www.hillbillyhousewife.com/70dollarmenu.htm
Or even $45 if you’re feeling the pinch:
http://www.hillbillyhousewife.com/40dollarmenu.htm