By Quentin Fottrell, Wall Street Journal

New York Mayor Michael Bloomberg’s plan to require residents to compost their food waste may cause headaches for some families, but experts say it could also help cut their rising grocery bills.

Under the proposal, by 2016 the city will require residents to separate their food waste for collection. Organic waste in New York City — which could otherwise be recycled for fertilizer or natural gas — currently accounts for 1.2 million tons or 35 percent of landfills, and a pilot program on Staten Island achieved a participation rate of 43 percent, according to the mayor’s office. Last year, Vermont introduced a bill to by 2020 require residents to recycle their food waste — and 33 percent of the organic waste in that state already gets composted.

Aside from the environmental advantages of composting, the effort may also be a boon for pocketbooks. Throwing out separate bags filled only with uneaten food could work as a big wake-up call for consumers, experts say. “We have a tendency to overbuy and overcook,” says Phil Lempert, CEO of grocery information site SupermarketGuru.com. “Awareness of how much food you’re wasting does help people buy properly. As prices go up, people also become more aware.”

And consumers today have every reason to be more judicious in the grocery store. The price of food purchased for consumption at home is expected to rise 2.5 percent to 3.5 percent in 2013, according to the U.S. Department of Agriculture.

As much as 40 percent of food goes uneaten in the U.S., according to estimates from the Department of Agriculture and the Environmental Protection Agency. Americans are, in other words, throwing out the equivalent of $165 billion in wasted food every year, according to a recent analysis by the Natural Resources Defense Council, a nonprofit environmental group. In fact, one study estimates, just 15 percent of wasted food would be enough to feed more than 25 million Americans every year. And one in six Americans currently lacks a secure supply of food, says Dana Gunders, an NRDC project scientist in San Francisco.

Grocery bills are the biggest household expense. The average American family of four spends between $632 and $1,252 per month on grocery bills, according to the Department of Agriculture’s April 2013 “Cost of Food” survey. Composting forces people to actually see how much food they’re throwing away and how much money they’re wasting, says Andrew Shakman, president of LeanPath, a Portland-based company that tracks food waste in industrial kitchens. LeanPath helped cut food waste at the UC Berkeley campus by 43 percent.

There are, of course, easier ways to cut one’s supermarket bill than composting. Consumers can waste less food by bringing a calculator to the store, making a note of when food goes bad, cooking only what they need and eating their leftovers, experts say. iPhone apps like Green Egg Shopper ($3.99) and Food Storage & Shelf Life ($1.99) can help keep track of perishables. One caveat to Bloomberg’s plan, however: “Recycling can also give less conscientious people a good excuse to waste,” Shakman says.