There’s one phrase I dread hearing from restaurant servers, apart from “No substitutions.”

It’s the inevitable response to every clean plate: “Wow, I can tell you hated your meal.”

Just a bad joke, sure, but the sarcasm reveals an ugly truth of the restaurant industry: No one cares when you don’t finish your food. As Washington prepares for Restaurant Week, when diners can get specially priced multi-course meals at more than 200 D.C. area establishments, it’s time to talk about the elephant on the table.

Plate waste is the term for the uneaten food consumers damn to the landfill. The United States wastes up to 40 percent of all food it produces, and edibles make up the biggest percentage of solid waste in landfills, according to the Natural Resources Defense Council. While up to 10 percent of all food bought by restaurants becomes kitchen waste, chucked before it hits the plate, consumers leave an average of 17 percent of their meals uneaten and take leftovers less than half the time.

It’s hard to find statistics on the local plate/kitchen waste division, but with Washington eateries multiplying in recent years, there’s more food service waste in the District than ever before. Like all that food, there’s plenty of blame to go around. Restaurants have turned Frankensteinian portions into a calling card, serving customers food piles that could feed families. That goes double during Restaurant Week, when each diner must order his or her own three-course meal. No sharing.

But putting the problem on the kitchen ignores consumerism’s most crucial element: choice. Diners could request smaller portions, or take more leftovers, or wait till next week when our kitchen overlords restore our freedom to share dishes. But our dining experience stays the same regardless of our efforts, so we have no reason to change.

Let’s find a reason. Restaurants could start clean-plate clubs, zero-waste rewards systems similar to frequent diners’ cards. Enough clean-plate outings (leftovers count) would earn a meal credit. Increase the reward based on the size of the party so it becomes a team effort — no more eight-person tables collectively shrugging at that Caesar salad.

And the more narcissistic restaurateur might consider charging for unfinished food. Some all-you-can-eat buffets already do this, mostly overseas. For customers, knowing they’ll have to pay for waste makes that fifth plate less appetizing.

These solutions could finally match appetites with the right amount of food. Economically, though, they’re nonsensical. Restaurants that cook to order earn the same profit whether you finish those nachos or not. They don’t care once the food’s in the dumpster, in part because our callousness gives them little incentive. Also, no establishment wants to promote obesity by encouraging customers to overeat.

Yet clearly some places care about waste, because they’re taking steps to curb it. More local eateries compost now, with the help of such companies as Fat Worm. And several establishments reroute unused food to nonprofits like the D.C. Central Kitchen.

So why not tackle plate waste, too? Restaurants should connect with groups like the Austin-based Halfsies, currently running pilot programs. Halfsies wants to let diners order half-portions at regular price, with the partnering establishment donating the surplus to a nonprofit.

No matter how we do it, we diners have to take responsibility for our own plates. By sending food back uneaten, we become culpable in restaurant waste. Because health regulations prevent donations of already served food, we’re sentencing those nutrients to an ignoble death at the nearest landfill and an afterlife of methane. We’re mocking the one-eighth of D.C. households battling daily hunger with our disregard for plate waste.

All this was best expressed by my recent Ted’s Bulletin server, who cleared our table after I failed to get my fellow diner to finish his fries. “Oh, that’s okay,” the waiter said, smiling. “Nobody finishes the fries.”

The writer is a journalist and film critic.