Costco may look like a bargain-hunter's paradise, but watch how much you load into your giant cart. Two new academic studies have found that buying in bulk might actually be more wasteful in the long run.

In one study, researchers from Cornell University interviewed Brazilian families in their homes to figure out how they shop, cook, and dispose of food. After analyzing the results, the researchers found that people waste food by purchasing too much, and then preparing too much food for meals without saving leftovers.

In a second study, researchers from the University of Arizona conducted a separate study on food waste, focusing on U.S. consumers. They found that families try to buy all their groceries in one major trip, which makes them buy items they end up not using before they go bad. "The problem is that people are not shopping frequently enough, which sounds counterintuitive," lead researcher Victoria Ligon said in a statement. "It seems that people in this country are very price sensitive at the grocery store, but tend to overlook the cost of discarded and unused food at home."

Here's how you end up wasting money without even realizing it. You go to Costco once a month, and perhaps throw in a trip to your local grocery store, too, to try to stock up on several weeks of groceries. But each time you go, you pick up a few extra things along the way. Throw in an unpredictable life and a few spontaneous trips out, and you end up with a lot of food going uneaten. The wasted food, plus the time it took to travel to each store, sneakily drains your wallet.

How can you stop wasting money? The experts recommend you use grocery sites like FreshDirect, which will let you order food whenever you need it, rather than doing one gigantic trip. They also recommend you keep a close eye on how much food you're cooking, and store all your leftovers properly so they last. And if you can't break your Costco addiction, stick to non-perishable goods while you load up on free samples.

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