Every rotten tomato or unwanted chicken wing represents wasted energy, since the calories in the food are never consumed. And the energy that went into growing the food, processing it, packaging it and transporting it to the consumer is also wasted.
Each year, American food waste represents the energy equivalent of 350 million barrels of oil, according to new research from the University of Texas.
That's enough to power the whole country for a week -- just sitting in the trash can rotting.
"As a nation we're grappling with energy issues," Michael Webber, associate director of the university's Center for International Energy and Environmental Policy, told AOL News. "A lot more energy goes into food than people realize."
This isn't small potatoes on a global level either. Agriculture is a major contributor to climate change, with the U.S. agricultural sector representing about 7 percent of the country's total greenhouse gas emissions in 2008, even before taking into account the energy used to process and transport the food.
So every time you order more french fries than you can eat, you're contributing to a major source of greenhouse gases and climate change.
"It's a significant amount of energy," Jonathan Bloom, author of "American Wasteland," a book on food waste, told AOL News. "It's not America's most pressing environmental problem, but I think it's the easiest one to solve."
Part of the problem is people's attitude toward food. Americans waste an eye-popping 27 percent of their food, Webber's study says. Almost one-third of the country's oils, fats, grains and dairy products end up in the garbage.
These figures may even underestimate the problem. For his study, Webber used statistics on food waste from a Department of Agriculture study in the 1990s.
A study by the National Institutes of Health, which measured food waste by calories, put the portion of food that goes uneaten at about 40 percent as of 2005.
"If you were to ship all of our food waste produced in one day to one central location, there'd be enough to fill the Rose Bowl," Bloom said, referring to the 90,000-seat football stadium in California.
Food is plentiful in America, thanks to naturally fertile farmland, a massive agricultural industry and federal subsidies. That means that people don't always think twice about tossing the leftovers in a way that might have shocked thriftier generations of the past.
According to the National Institutes of Health study, the American food supply per person has risen by almost one-third from 1970 to 2005, as measured by calories.
"We have a cheap food policy in America," Webber said. "When things are cheap, people don't care so much about wasting it."
The federal government has offered tax breaks on items including furnaces and insulation in a bid to improve energy efficiency in America and fight climate change.
The government also established the Energy Star program, which highlights household appliances that meet federal energy efficiency standards.
Webber thinks more could be done to prevent food waste.
He says the government could reduce subsidies to curb overproduction. Consumers could think more about purchases so they don't end up buying food that will rot in the fridge without ever making it to the plate.
He also says that measures including a public information campaign and better technology on farms could make massive energy efficiency gains in the food sector, at comparatively little cost.
That would mean less money wasted and fewer greenhouse gases emitted.
"We can have rapid changes of behavior if people have the right motivations," Webber said. "People just aren't conscious of what this waste means."