Washington Post illustration using iStock images

When the founders of Modern Market opened their first location in Boulder, Colo., in 2009, they hoped to build a restaurant that they would want to eat at every day. For Anthony Pigliacampo and partner Rob McColgan, that meant serving smaller dishes. Often, Pigliacampo said, “I don’t want a ton of food.”

Look around the chain today, and you’re likely to spot someone with half a sandwich or half a pizza. That’s no oversight. The fast-casual, “farm-fresh” eatery, with locations in Rockville, Bethesda and a new one in downtown Washington, offers everything on its salad, sandwich and pizza menus in half portions.

Building upon the surging popularity of tapas and family-style shared plates, the option offers freedom to fans of the choose-your-own-adventure meal. It also gives diners greater control over calorie consumption and helps reduce food waste, a problem estimated by the USDA to affect 30 to 40 percent of the food supply.

Phillip Blane, executive chef and co-owner of Unum in Georgetown, said offering half portions lets people create more of a tasting-menu experience at the contemporary American restaurant, allowing them to try more dishes than just an appetizer and an entree. A meal could begin with the roasted cauliflower starter or a light half portion — say, the roasted eggplant ravioli. Diners can progress through the smaller size of fish and meat courses, the grilled branzino and rack of lamb perhaps, before closing out with dessert.

At Joselito, a modern Spanish cafe on Capitol Hill, a spectrum of dish sizes — tapa, “media ración” (equal to two tapas or a light entree) and “ración” (a family-style portion equal to four tapas) — also gives diners flexibility. Owner Javier Candon decided to offer those portions to introduce diners to the way he grew up eating in Spain, where the varying sizes are common. “It’s nothing that we have invented,” he explained.

More restaurants are offering half portions of their food, including the chain Modern Market, where you can halve any pizza, such as the cremini kale. (Marvin Joseph/The Washington Post)

Smaller dishes can be good for health-conscious diners, who can order a salad and a half portion and still have a satisfying meal. Dana Gunders, senior scientist at the Natural Resources Defense Council and author of “Waste Free Kitchen Handbook,” said that half portions are a “win-win-win.” “We have such enormous portions,” she said. “There’s only two things happening with those extra calories. Either we’re eating them, and that’s not good for other reasons, [or] we’re not and they end up going to waste often.”

Although Pigliacampo said Modern Market doesn’t have the ability to track food waste, he’s noticed that “smaller portions tend to get consumed completely.” Candon has had a similar experience at Joselito, where plates usually go back to the kitchen completely clean.

Research backs the restaurateurs’ experience. A study conducted by the University of Minnesota in a worksite cafeteria and a golf club restaurant showed that plate waste declined in both settings when diners were offered half-size dishes. In another study, merely giving diners the option to order half portions, even if they didn’t actually choose them, was more effective at cutting back on waste than inserting a “Save Food” logo on a menu, said Gustavo Porpino, an analyst with the Brazilian Agricultural Research Corp. who worked with Cornell University’s Food and Brand Lab on a paper on the topic in 2015.

The option has proven to be popular with diners, too. At Modern Market, people take advantage of ordering a single item in the smaller size as often as they do a full-size dish or combination of multiple halves. Unum sells more half portions than full-size plates; at Joselito, the balance is still in favor of tapas-size plates, by a count of about 2 to 1.

Financially, though, Modern Market’s Pigliacampo said offering half portions “probably hurts us as a business.” Although the price of a half portion is a little more than 50 percent of the entree, the same amount of work goes into prepping a smaller dish as it does a larger one. (The desire to get the most bang for their buck might prompt diners to order bigger dishes, even if they don’t intend to eat the whole thing, Gunders said.)

Plus, when diners order multiple half portions, the kitchen has to expend more effort to keep up with demand, a problem that especially affects high-volume fast-casual settings.

Seasonal vegetables sprinkled with goat cheese at the Spanish cafe Joselito, which offers a “media ración” — equal to two tapas. (Dixie D. Vereen/For The Washington Post)

Joselito’s Candon said the varying plate sizes can make things a bit more complicated, mostly because the kitchen has to pay extra attention to tickets to make sure it’s sending out the right portion of each dish. Restaurants also have to be more thoughtful about the type of food served, because not everything is easily adapted to small, medium or large portions.

Even with the extra coordination, Candon said he is “extremely happy” with the way his experiment has gone. So are diners, who he said have embraced the fun of building their own menu.

That’s the kind of experience restaurant-goers can create at other area restaurants, including Bar Civita, Rasika, Ardeo+Bardeo, Bibiana, Bombay Club and the Fabio Trabocchi family of restaurants (Casa Luca, Fiola Mare, etc.), where half portions are available on certain dishes. Even if the option isn’t explicitly listed on the menu, as at some of these spots, Gunders said diners shouldn’t be discouraged. Especially at restaurants known for excelling at customer service, you can always ask.