On a cool spring day, you find yourself with a hankering for beef stew. There are many ways to eat this desired meal. You could go to the grocery store, purchase the ingredients, and assemble them at home. You could outsource all of that labor and simply order the dish at a restaurant. Or, like an increasing number of Americans, you could take the pre-portioned ingredients out of a meal-kit box and follow the printed instructions.

Some of the resulting plates will be better than others. Discerning palates might be able to tell them all apart, but that is hardly the most effective technique. The real differences appear in the hours and days after the meal—in the remaining stalks of celery moldering in the back of a vegetable crisper, or the pile of cardboard boxes waiting to be recycled, or the scraps of stew being repurposed. With apologies to the French politician and gastronome Jean Anthelme Brillat-Savarin, you are what you eat—the day after cooking it.

With the decline of traditional home cookery and the rise of efficiency-obsessed start-ups, however, leftovers face a new challenge: finding a role at a time when meals are increasingly taken outside of the home, or assembled from kits. Is there room for leftovers in such a world?

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In the court of Henry VII, it was customary for diners to leave food on their plates that could later be given to the lower classes. Using leftovers as a compulsory charity, a practice referred to as “manners,” helped clarify the social order. In America, the term leftovers dates from the early 20th century, contemporaneous with the rise of refrigeration. Then as now, leftovers were inexorably linked with technological change. From the 1930s through the ’50s, the ability to transform leftovers into interesting dishes was a significant part of middle-class culture. This tradition underwrote cookbooks that now feel wonderfully dated, like Ruth Berolzheimer’s 500 Delicious Dishes from Leftovers, which includes a recipe for Prune Whip Pie. As the novelty of refrigeration wore off, concoctions like Prune Whip Pie lost their appeal. Leftovers fell victim to refrigeration’s ability to preserve ingredients for longer than diners might want to eat them.

Home economics is now an outmoded term, but its name contains an essential truth: The economics of eating a meal at home were once substantively different from dining out. Home cooks spread the returns on labor and resources over time. Today’s dinner becomes tomorrow’s lunch. The unused celery from a stew later reappears in a soup. Investments that make little sense when used in one sitting became viable when stretched over many. Leftovers were the defining features of home cooking.

A restaurant affords economies of scale. Whereas a home cook might divide a head of garlic over a week of meals, a restaurant divvies it up between contemporaneous diners. By prepping in bulk, restaurant kitchens can pursue different culinary goals than the home cook. Making parsley oil, for instance, is a nuisance for a weeknight dinner at home, but a negligible investment of time and resources for a business that serves 100 diners per sitting. Like a time-share, allocating scarce resources across many diners allows multiple people to partake in consumption patterns that they could not otherwise enjoy.

Anyone who has tried to prepare a recipe from a restaurant cookbook can appreciate this difference. A recipe can only be scaled down by so much. Appliances are less effective with tiny doses, and one can hardly bake with an eighth of an egg. That leads to instructions like “reserve in an airtight container, refrigerated, for up to 2 weeks”—as the recipe for “White Balsamic Pickling Liquid” instructs in Daniel Humm’s NoMad Cookbook. Roughly a third of that liquid is used to pickle a single shallot. Later, along with one-tenth of the recipe for “Brown Butter Sabayon” and one-twenty-fifth of the recipe for “Chicken Jus,” that pickled shallot garnishes the thigh of a roasted chicken. The whole affair requires more burners than the normal home allocation of four, but it is quite tasty. Cooking this way at home produces its own kind of leftovers—a constellation of discrete preparations that cannot be relied upon to satiate hunger on a subsequent day.

One solution: Do the purchasing and basic prep work in bulk, like a restaurant does, but then deliver the fractional ingredients to home kitchens. Cooking would change if home chefs only had to purchase a single celery branch or two tablespoons of an esoteric vinegar. That’s the promise of meal kits, like those distributed by Blue Apron, Plated, and Hello Fresh. They contain everything needed to make a dinner—and nothing more. Instead of sharing a head of garlic with the neighboring table, you share it with your neighbor—or somebody in another state. Consequently, there are no leftovers.

A lack of leftovers can be justified in many ways, and the meal-kit industry liberally spreads such justifications atop their services. “No waste!” trumpets the Canadian start-up Chef’s Plate. “Ingredients are pre-portioned for each recipe.” Pre-portioning does eliminate waste at home, but it doesn’t eliminate it entirely. Whatever waste there is simply happens out of sight, in a facility. Blue Apron, for instance, aims for 3-percent waste—a meaningful reduction over the reported 40 percent suffered from grocery meals.

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But even if industrial logistics reduce waste on behalf of home cooks, they also displace that waste as an aesthetic experience—the good of leftovers vanish as much as the ill. Meal-kit portioning contributes to that end, too. Blue Apron meals tend to offer roughly 700 calories per serving, due to a combination of ingredient choices and relatively strict portion controls. Like the focus on waste reduction, this nutritional strategy squeezes leftovers out of the dining experience. There is no excess to indulge in—either at dinner or during another meal.

Even when eliminated, leftovers remain powerful social objects. Their absence in restaurant meals and home meal kits reveal eaters’ attitudes towards consumption, economics, and waste. When it comes to food, these three concepts are all related, but vary from product to product. In an essay comparing Soylent to Slimfast, Rachel Stone observes that the two drinks achieve the same purpose, yet couch their functions in different terms. “By emblematizing the absence of food, both Soylent and SlimFast fetishize austerity,” she writes. Soylent makes distraction “a sinful indulgence,” as SlimFast does for consumption. One person’s biohacking is another’s dieting.

As a catch-all term to describe food excesses or frugality, leftovers turn out to have a similar role: They allow fixations on portion control to be passed off as environmentalism, or ambivalence toward cooking to be reframed as the pursuit of efficiency.

At a time when home cooking is rapidly declining in America, the meal kit promises to teach a generation ignorant of home economics how to make dinner. Home cooks might not make Seared Salmon and Seasoned Labneh with Freekeh, Kale, and Dates every night, but most of the skills involved can be applied to other recipes. As Blue Apron’s  COO, Matt Wadiak, told National Geographic, “I want people to cook with Blue Apron all the time, but my practical answer is I want people to cook at home.”

The limitations of this strategy reveal themselves when one tries to make a meal-kit recipe without the box of carefully portioned ingredients. Take the aforementioned salmon recipe. Freekeh and labneh are not sold in quarter-cup increments, so budding home chefs must use a fraction of larger purchases. Garlic cloves are not sold in threes, so they’d use a few from an entire head and save the rest. Salmon fillets, which Blue Apron treats as standardized units, actually fluctuate in size. And that is to say nothing of recipes that call for a single egg or teaspoons of specific spice blends that cooks would have to assemble from bulk purchases. It’s certainly possible to make Seared Salmon and Seasoned Labneh with Freekeh, Kale and Dates without a meal kit, but completing the process without the help of professional logistics firms will almost inevitably involve spare ingredients and leftovers.

There is nothing inherently wrong with that. The leftover fish will still taste good tomorrow. The remaining garlic cloves, dates, labneh, and freekeh can be used in other recipes if they don’t expire first. Reproducing meal-kit recipes without the boxes, while feasible, results in a pantry that is heavy on the sorts of ingredients that are only used in small and occasional doses. The experience of measuring ingredients, saving them, and keeping track of expiration dates, however, is totally different. This is the ultimate proof that meal kits are not the same as home cooking in its traditional sense. The absence of leftovers embodies that difference.

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While often desirable, the pursuit of efficiency also changes behavior. Most drivers only use their vehicles for a small fraction of the day; car sharing—and future fleets of driverless cars—address this problem. Start-ups like Airbnb strive to prevent any room from ever going unused. While not often mentioned in the same breath as Uber or Airbnb, meal-kit start-ups belong in the same category. They apply economies of scale common to fleets and restaurants to domestic cooking.

But something is lost in these transactions. City dwellers no longer have spare rooms or couches. Drivers in Uber’s idealized future can no longer just jump into their cars for a jaunt whenever they wish to do so. Those may be reasonable prices to pay for reduced waste and greater efficiency, but they also transform the ways people live. As foodways change, leftovers are changing, too. Soon enough, they might represent what home cooking once meant, but no longer does.


This article appears courtesy of Object Lessons.