From milk to meat, cereals to soda, grocery shopping has gotten a lot more expensive and experts warn the worst is yet to come.

"We're going to see anywhere from 8 to 15 percent increases," said Phil Lempert, NBC's Supermarket Guru.

Lempert said that's because of rising fuel prices, greater worldwide demand for food and the conversion of corn to ethanol. More than ever, it pays to be a savvy shopper.

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"You've got to shop the entire store," he said. "You've got to shop the dairy department, in the frozen food department, the canned foods department. And, you'd be surprised. You can easily cut 20 to 25 percent off your shopping bill."

NBC 6's Patricia Andreu put Lempert's theory to the test.

At Costco, she found that fresh green beans cost more than twice per pound than the frozen and organic green beans.

The fresh strawberries were $1 more per pound than the frozen kind. Regular blueberries were 20 cents more per pound than a frozen and organic bag.

Lempert said he is a fan of frozen options, especially if the fruit is out of season.

"In order to ship those products, they're picked before they are ripe, so they're not going to have the flavor and they're not going to have the nutrients you'd expect," he said.

Even in the produce section, it's smart to shop around. Large tomatoes cost almost $1 less per pound than the kind on the vine.

Also, look for alternatives. When cooking, stewed or diced tomatoes can save you up to 75 percent!

"The service departments, like the bakery department, the deli counter or the cheese table that has service personnel, they have a higher overhead so they're going to take a larger markup," Lempert said.

For example, Swiss cheese at the deli counter costs 60 percent more than a pre-sliced, prepackaged Swiss in the dairy aisle. Store brands are a big cost-cutting option.

"You can save between 10 and 30 percent when you buy private label products," said Maria Brous of Publix supermarkets. "So, right there there's a savings on your receipt."

Believe it or not, buying more can be better. At Publix, family packs of meat typically run 20 cents less per pound than the smaller packages.

And, keep your eyes peeled for sales from advantage buys.

"That means we received a discount from our supplier and we're passing it along to our customer," Brous said.

Finally, never shop without a list.

"Studies have shown that you will spend 40 percent more than those people who have lists because we see more impulse items as we walk around the store," Lempert said.

For more from the Supermarket Guru, visit www.supermarketguru.com.