With the worst inflation in food prices in 20 years Americans are changing the way they eat to try and keep food costs in line with their incomes.

According to the United States Department of Agriculture Center for Nutrition Policy and Promotion a family of two eating on a thrifty meal plan will spend $4,092 on food this year, which is up $252 from a year ago, while the same size family eating on a liberal food budget will spend $8,008.80 on groceries this year, an increase of $496.80.

USDA food plan costs are based on preparing all meals and snacks at home.

Trying to keep grocery costs down means Americans are adapting a variety of strategies that include cutting out restaurant meals, shopping supermarket sales, using coupons, buying less expensive foods and eating less.

Among the foods that cost more are ground beef, milk, chicken, apples, tomatoes, lettuce, coffee and orange juice, according to the federal Bureau of Labor Statistics the AP reports.

There are a variety of factors driving food costs up, with the advent of bio-fuels made from corn, corn has become more expensive and corn goes into animal feed, directly driving up the costs of beef, pork, chicken, milk and eggs, along with anything sweetened with high fructose corn syrup. The shortage of corn, along with wheat, has also driven up the prices of cereals, bread and pasta.

The rising cost of gasoline has increased the cost of trucking food around the nation further driving up prices.

Increasing prices have caused the United States Department of Agriculture Center for Nutrition Policy and Promotion to increase the amount of money it states is needed to feed individuals or families on plans that it labels thrifty, low-cost, moderate-cost or liberal. All plans are based on preparing all meals and snacks at home, the department says in a statement on its website.

In February 2008, the cost of feeding a family of two on a thrifty plan was $78.52 versus $74 a year earlier, while the cost of eating on a liberal plan was $154 versus $144.50 in February 2007, according to the USDA.

That increase makes it even more challenging for Americans to make sure they are eating nutritious meals and the USDA emphasizes that eating well is important for health.

"Americans still need to improve their diet; Americans need to narrow the gap between scientifically based nutrition guidance and consumer behavior that may increase the risk of illness from nutrition-related diseases," the USDA wrote in its research article on the thrifty food plan.

The value of the thrifty food plan is the basis for food stamp allotments.