12 hours ago

A science-backed tip to waste less food on Thanksgiving

It is a great irony of American life that we celebrate Thanksgiving - a holiday meant to commemorate a group of people who narrowly escaped starving to death - by wasting more food than on nearly any other day of the year.

On a typical day, U.S. households throw out roughly 230 million pounds of food, according to data from ReFed, an American nonprofit that aims to reduce food waste. This Thanksgiving, ReFed estimates that number will rise to 316 million pounds. That’s more than $550 million worth of groceries, or enough to feed every food-insecure person in the United States five times.

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There’s also an environmental cost. Growing, processing, packaging, refrigerating and transporting all that food generates greenhouse emissions, and once it hits the landfill, it rots and pumps out methane, an extra-potent planet-warming gas. This Thanksgiving’s total, alone, is expected to warm the planet as much as driving 190,000 cars for a year.

But the good news is that all this waste is avoidable, according to ReFed President Dana Gunders. “Not throwing food away is one of the most instant actions you can take to reduce your greenhouse gas footprint,” she said.

She recommends using the Natural Resources Defense Council’s “Guestimator” tool to plan how much food you’ll really need, making sure you have enough containers and freezer space to hold your leftovers and prompting your guests to take some food home with them.

But there’s one more science-backed way to waste less during holiday meals: Try serving on smaller plates.

When people serve themselves at a buffet, cafeteria or Thanksgiving table, they tend to fill their plates, according to Brenna Ellison, director of the Center for Food Conservation and Waste Reduction at Purdue University. Sometimes, their eyes are bigger than their stomachs and they wind up scraping food into the trash. Smaller plates lower the impulse to overdo it on the first serving - but they don’t stop anyone from going back for seconds or thirds if they’re still hungry.

“If you put out slightly smaller [plates] and people go back more often, that’s still a better outcome than putting so much on in the first place that you’re just dumping it all in the trash at the end,” Ellison said.

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The science of smaller plates

Smaller plates cut food waste because our brains are gullible.

If you put the same amount of food on two plates with different sizes, “it looks like the smaller plate is fuller,” said Mei Peng, who studies food science at the University of Otago in New Zealand. “It creates an optical illusion.”

Ellison tested the impact of this illusion on college students noshing at all-you-can-eat buffets in campus dining halls. When the students were given plates that were just 10 percent smaller, they served themselves slightly less food, and they cut their food waste by about a third. She attributed that to people taking a more realistic amount of food on the first serving and going back for more only if they were still hungry.

Thanksgiving hosts shouldn’t worry that their guests will leave with an empty stomach: It’s not clear that smaller plates make people eat much less.

Scientists have fiddled with the sizes of plates, bowls, utensils, serving spoons, glasses and packaging to see whether they can get people to lower their calorie intake by shrinking their tableware. The jury’s still out, according to Gareth Hollands, a behavioral scientist at University College London who did a meta-analysis reviewing the research on the subject so far and then conducted a new lab experiment.

The evidence, he said, “leans in that direction of smaller plates reducing consumption but with generally small and inconsistent effects.”

But he said there’s pretty good evidence - in his study, Ellison’s study and others - that smaller plates can nudge people to take only what they need and waste less food.

If you don’t have smaller plates to serve on, you can always do the next best thing: “You can still keep it in mind to not overload your plate and just go back for seconds,” Gunders said. “Absolutely, stuff yourself all you want - but having extra on your plate that you’re not going to eat doesn’t really do anyone any good.”