I used to live off less. As simple as this sounds, the trick is to buy real, minimally processed food. You just need to mimic healthy cultures that live off much less.

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General: Most real foods are commodities. Brands mean little and you pay a premium for the ads on TV. Buy generic. Also, cooking simpler, authentic recipes will go a long way. Rice and varying stir fries are a great way to live. If you don't like rice, the problem is the sauce.

Carbs: 50 lbs of Riceland Enriched Rice is slightly over $17 at Sam's Club (go with a friend with a membership). I used to buy 5 lbs of potatoes for a dollar. Finally, I would stock up on pasta when it fell below $0.89/lb (this happens less often now, but $0.99 is a decent price point). I also do buy standard, American bread, and discovered the Wheat Price First at Walmart ($0.89 a loaf that is nutritionally fine, big, and tastes great).

Protein: Buy meats in bulk on sale and freeze. A fryer chicken will do very will in a slow cooker. Watch dairy and egg prices closely and buy when they become cheap (right now, prices are dropping for milk and becoming quite reasonable). Tofu can be a steal at some Asian supermarkets. Finally, some Walmarts have loose pinto bean bins (primarily in Hispanic areas) that are dirt cheap per pound. Finally, I do buy store brand peanut butter.

Fruits and Vegetables: Fresh, in season is best. If you have a fresh grocer or Asian grocery, they can have some amazing deals. Try new vegetables. I never knew how much I would love bok choy, and it is so healthy. Also, canned and frozen are not a terrible alternatives from a health perspective (frozen can actually be better in terms of preserving nutrition depending on the time from picking to store). Last year, I bought maybe 50 cans of cut green beans for $0.29/lb (they last for over two years).

Fats and flavoring: I use olive oil as my oil, and buy EVOO from Sam's Club. I also own canola as a base for stir fries. Other flavorings come from South and East Asian spices and sauces (master a good Chinese white sauce). Spice prices are a rip off in most grocery stores. I buy in bulk from Sam's, or go to ethnic grocery stores. Hispanic stores are great for most Western spices. Finally, in season, I grow basil in a pot because it's easy and tastes so good fresh.