Image: Home kitchen © Don Farrall, Photodisc, Getty Images

The average American family of four spends $727 a month on food -- but you can spend substantially less and still be healthy.

Nutritious meals for two adults and two kids can be prepared for just over $500 a month, said Robert Post, the deputy director for the U.S. Department of Agriculture's Center for Nutrition Policy and Promotion. A single person can get by with a monthly food budget of about $225 a month.

"You do not have to sacrifice the healthy choices on a low budget," Post said. "There's a way to do it."

If you're newly broke, or trying to save money for other purposes like paying down debt, your grocery list is a great place to look for savings. Although food is the third-largest expenditure for most households, after housing and transportation, it's also one of the most flexible and can easily be trimmed on the fly. Here are some general principles to keep in mind:

Eat mostly at home. U.S. households on average spend 41% of their food budgets outside their homes, according to the U.S. Bureau of Labor Statistics' Consumer Expenditure Survey (the proportion is 44% for singles). While you may think you're saving money dining off the dollar menu, you could be courting health problems, since the cheapest fast food items are often the ones loaded with fat and sugar. The foods that should be filling half your plate -- fruits and vegetables -- may be hard to find or overly processed when you buy them from fast-food outlets, so ultimately you'll save money and eat better preparing food at home. (Also, read Donna Freedman's column on eating on $4 a day.)

Skip the processing. Steer away from foods with lots of additives, chemicals and packaging; they're often not as good for you, and they can drive up the cost of your groceries. Instead, opt for foods that are as close to their natural state as possible. That may mean you have to spend a little more time preparing your meals, but I've included helpful tips below on how to make that more convenient.

Demote meat. Beef, chicken, pork and fish often take a starring role in American meals, whereas in less-wealthy countries they're often supporting players or make only cameo appearances: Think bowls of rice or grain topped with lots of veggies and a few bits of meat or seafood. Or you can skip meat entirely for much cheaper protein sources, such as eggs or beans (a half cup of beans has as much protein as 3 ounces of steak).

Liz Weston

Liz Weston

Nuts, legumes, seeds and dairy products, including milk, cheese and yogurt, are other good sources of protein. Water-packed canned tuna and salmon, which you frequently can find on sale, can help you get the 8 to 12 ounces of seafood the USDA says you should have every week. The new "Healthy Plate" guidelines, which the USDA recently introduced to replace the old food pyramid, reflect these changes by replacing the old "meat and beans" category with "protein foods."

Promote veggies. The typical household should spend about 40% of its food budget on fruits and vegetables, Post said. Buying in-season produce on sale is one way to save while filling your plate. Also consider frozen or canned vegetables and fruit. Frozen produce is typically processed soon after harvest, which preserves more nutrients, but be careful with canned foods, because they can have too much salt and sugar. Opt for low-sodium versions and fruit packed in juice, not syrup, Post recommended. If you have a farmers' market nearby, consider shopping there, especially toward the end of the day when you may be able to negotiate deals on produce farmers would otherwise have to haul home.

Go for the grains. Wheat, rice, oats, cornmeal, barley and cereal grains are filling and fairly inexpensive, especially if you buy in bulk. Opt for whole grains, which offer more nutrients and fiber. Oatmeal makes a nutritious, satisfying breakfast for just pennies a serving, while brown rice can be served at any meal (it's pretty good heated up with milk and honey).

Watch the waste. Studies estimate that Americans waste up to 40% of our food supply. If that's the case in your household, you could save hundreds of dollars a year just by patrolling your refrigerator, freezer and pantry each day so you can use stuff before it rots.

Drop your bad habits. Alcohol, tobacco, soda and sugary treats may be pleasurable, but they don't fill nutritional needs. That's not to say you can never indulge, but when money's tight, you need to rein in your guilty pleasures.

If you need help finding recipes or more suggestions:

  • Use the USDA's "recipe finder" or search for "budget recipe" sites.
  • Your local library has budget cookbooks and other information on saving money.
  • Check out frugal-living websites; a good one to try is the Dollar Stretcher.

If money's really tight, you shouldn't be reluctant to ask for help. The federal government's food assistance program, once known as food stamps and now called the Supplemental Nutrition Assistance Program, can help low-income people buy groceries. SNAP served up $64.4 billion in benefits during the 2010 fiscal year, a fourfold increase from 2000. If you don't qualify for SNAP, you can still get food from a community food bank.

If your problem is a lack of time to prepare budget meals -- which leads to the temptation to spend more eating out -- here are ways to make sure you still can eat well on a budget:

Get a slow cooker. You can pick up a basic Crock Pot for as little as $16 online or find one for even less at a garage sale. Slow cookers allow you to assemble a meal in the morning so you can have a hot, ready-to-eat dinner when you get home.

Cook once, eat twice. Make double the number of servings you need and freeze the excess to reheat later. Some foods don't freeze well, such as potatoes and crisp vegetables, but most -- including soups and stews -- do just fine. Use freezer-weight storage bags or containers, and mark them with the date so you can use them within three months.

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Learn to love lentils. Like beans, these legumes are loaded with protein and iron but are typically much faster to prepare, with cooking times under 30 minutes for most varieties. Couscous and quinoa are two grains that are fast to prepare as well -- five minutes for couscous, 15 minutes for quinoa, compared with 30 to 40 minutes for brown rice.

Have some go-to recipes. Egg dishes, pasta and many casseroles tend to be easy to throw together in a hurry. Keep some veggies, such as a carrot and celery sticks, in a glass of water in the fridge for snacking while you pull together the meal.

Liz Weston is the Web's most-read personal-finance writer. She is the author of several books, most recently "The 10 Commandments of Money: Survive and Thrive in the New Economy" (find it on Bing). Weston's award-winning columns appear every Monday and Thursday, exclusively on MSN Money. Join the conversation and send in your financial questions on Liz Weston's Facebook fan page.