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The behavioral economics of Thanksgiving


This column originally appeared in the Food section.

It happens every year. It's not that you resolve to be virtuous on Thanksgiving, just reasonable. Two plates of food, and no more. One piece of pie, and that's enough. But when you're sitting at that table, staring at that food, there is no more self-control. No more reasonable. You stop when you can hardly breathe.

Or maybe I'm projecting. This column, however, will not be about exercising self-control at the table. It's Thanksgiving! Rather, this column will be about something far more powerful: exercising some economic principles.

For a long time, economists operated under the "rational actor model." Human beings were thought to be rational creatures who correctly weighed costs and benefits and calculated the best choices for themselves. Then some economists met some human beings and realized we don't really work like that. The result has been the rise of "behavioral economics," which attempts to build the responses of actual human beings into its models.

MIT economist Dan Ariely is a pioneer in the field. His bestselling book "Predictably Irrational" is as good an introduction to the discipline as you'll find. Human beings, he argues, aren't just irrational: They are irrational in predictable ways and in predictable circumstances. That means we can plan for that irrationality beforehand, when we're still feeling rational.

I asked Ariely how he would set up his Thanksgiving feast to limit overeating without having to exercise self-control. His answer was to construct the "architecture" of the meal beforehand. Create conditions that guide people toward good choices, or even use their irrationality to your benefit.

"Move to chopsticks!" he exclaimed, making bites smaller and harder to take. If the chopsticks are a bit extreme, smaller plates and utensils might work the same way. Study after study shows that people eat more when they have more in front of them. It's one of our predictable irrationalities: We judge portions by how much is left rather than how full we feel. Smaller portions lead us to eat less, even if we can refill the plate.

Speaking of which, Ariely suggests placing the food "far away." In this case, serve from the kitchen rather than the table. If people have to get up to add another scoop of mashed potatoes, they're less likely to take their fifth serving than if they simply have to reach in front of them.

"Start with a soup course," he says. That is what economists refer to as a default: Rather than putting everything on the table for people to choose, you begin by making the choice for your guests. If the first course is relatively filling and relatively low in calories, everyone will eat less during the rest of the meal.

Indeed, it's not a bad idea to limit the total number of courses. Variety stimulates appetite. As evidence, Ariely brings up a study conducted on mice. A male mouse and a female mouse will soon tire of mating with each other. But put new partners into the cage, and it turns out they weren't tired at all. They were just bored. So, too, with food. "Imagine you only had one dish," he says. "How much could you eat?"

What you eat, of course, is also important. Studies show that people aren't very consistent in the amount of calories they eat each day, but they're very consistent in the volume of food they eat each day. Thanksgiving is an exception to that consistency, but probably not to the underlying rule. Satisfaction doesn't depend on caloric intake; low-calorie, high-fiber foods and foods high in water content are filling. Thus, the more broccoli rabe there is at the table, the better.

Speaking of which, take a page out of the pilgrims' book and make sure all the food at the table was cooked by someone in the house. Economists believe that the obesity epidemic is largely attributable to the rise in food we don't make for ourselves. In 1900, it was hard to snack on potato chips because it was time-consuming for a member of the household to make potato chips. Today, of course, things are different, and there is a surfeit of vending machines and drive-throughs and supermarkets. But on Thanksgiving, make like you're in Plymouth, and ensure all of the food is homemade. There will be fewer calories available if Grandma's stuffing isn't supplemented with bowls of chips and cheese.

For all that, Ariely's main advice is not to worry too much about Turkey Day. "I don't think Thanksgiving is a time to watch your diet," he says. "How many calories can you put away in a day? Maybe 5,000 or 6,000 calories, if you really try hard." The problem, he says, is another human irrationality: remembering to pay attention to the season's big meals but not the everyday ones in between. The solution to overeating, Ariely says, "comes from [making] small changes across many normal meals."

That seems rational. But if you insist on trying to cut back at Thanksgiving, Ariely does have one more piece of advice: "Wear a very tight shirt."

Photo credit: Larry Crowe/AP.

By Ezra Klein  |  November 25, 2009; 11:30 AM ET
Categories:  Articles , Food  
Save & Share:  Send E-mail   Facebook   Twitter   Digg   Yahoo Buzz   StumbleUpon   Technorati   Google Buzz   Previous: 'Even LBJ would be stuck if he drew this hand'
Next: We all pay for obesity


The food/mouse/sex thing is a bit of a stretch, unless you have some weird George Costanza pastrami sandwich kinkiness goin on.

Posted by: CarlosXL | November 25, 2009 11:50 AM | Report abuse

I think we need some kind of ruling on the photo here. My sense is that's a chicken trying to pass itself off as a turkey.

Posted by: zeppelin003 | November 25, 2009 11:50 AM | Report abuse

About the Thanksgiving meal, I have a high level of doubt that anyone has ever become obese from eating too much food and dessert at Thanksgiving dinner, even if one were to gorge and eat an immense amount of food, the most you'd ever gain is 2 or 3 lbs.

Its the other 355 days that kill us, as opposed to the 10 or so holidays/vacations.

Posted by: zeppelin003 | November 25, 2009 11:58 AM | Report abuse

Chopsticks are evidence that God hates China and wants it to be unhappy.

So far today I've read some nutjob on Slate trying to ban green beans, a couple of different people with turkey in their sights, and now Ezra trying to ban Thanksgiving altogether by making it indistinguishable from just another day and I ask myself: Why can't all you silly people go off and do things the way you want and leave the rest of us alone? Why do you feel compelled to urge us all to have a holiday as dour and thankless as yours?

If you don't like green beans or turkey, pass the plate on and shut up about it already.

Posted by: pj_camp | November 25, 2009 12:57 PM | Report abuse

Klein's become a scold at the ripe old age of... twenty five.

There's more than a hint of the fanatic in him, too, no?

Posted by: msoja | November 25, 2009 1:30 PM | Report abuse

how about serving some kind of meat that's dry and unappetizing?

Posted by: bdballard | November 25, 2009 2:19 PM | Report abuse

the more broccoli rabe on the table at any meal, the better as far as i am concerned. oh that it were in season in november....

Posted by: trishka_cvo | November 25, 2009 2:23 PM | Report abuse

So, at Thanksgiving you should sit down to a meal that is as undesirable as sex with your spouse.

Ezra, this is not good.

Posted by: Bloix | November 25, 2009 2:49 PM | Report abuse

I thought this was a good article. Professor Ariely is Israeli by the way -- good thing he knew what Thanksgiving is :-)
I'll keep your advice in my mind as I eat slowly.

Posted by: mattyhoff | November 25, 2009 7:25 PM | Report abuse

Dan Ariely is at Duke University now, not MIT.

Posted by: chase-truth | November 26, 2009 9:28 AM | Report abuse

Ariely teaches at Duke but has an affiliation with MIT. Perhaps it's not incorrect to call him an MIT economist, but Duke economist is probably more accurate, no?

Posted by: jeffwacker | November 26, 2009 12:37 PM | Report abuse

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