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Is There a Scientific Explanation for Food Comas?

Researchers over-fed fruit flies to understand why you pass out after Thanksgiving dinner.
James Porter/Getty

It starts several hours before the table's set and runs several hours after the last plate is cleared. You start by nibbling on meats and cheeses, possibly pigs in blankets, and by the time the bird emerges from the oven, you're already full. Still, you gorge on the stuffing, the rolls, the gravy, the pie, the leftovers, the everything, because hey! It's Thanksgiving. You've waited all year for this. You deserve it.


When the binge is over, you carry your swollen stomach carefully to the couch, flop your body down horizontally, and drift off into a sweaty, meaty sleep.

This, of course, is your food coma. You know it well: It's the exhaustion that sets in after a Kobayashi-size meal. You're familiar with the phenomenon anecdotally, but the funny thing is, there's hardly any scientific explanation for why it exists. We don't know why we zonk out from overeating. But a new study shows that humans are in good company: By stuffing the tiny bellies of fruit flies, researchers from the Scripps Institute in Florida discovered that big meals lead to a food coma of sorts for insects, too. The more food the fruit flies ate, the longer they slept after their meal.

Humans are of course not fruit flies, but the insects show all the hallmarks of human-like sleep patterns, plus behaviors that suggest they possess a similar mechanism for regulating appetite and satiety. This makes them a useful model for studies on feeding, says head researcher William Ja, associate professor at the Scripps Research Institute.

"If food comas are a real phenomenon that happen not only in flies, but in mammals and people too, then it must serve some important biological function," says Ja. "Maybe it's just good for digestion, or maybe running around with a stomach full of food is horribly damaging to your gut."

Ja and his team have begun testing the idea that a post-meal sleep helps with nutrient assimilation and absorption, which could have been important for our ancestors when it was difficult to obtain certain nutrients in nature.


In the research on fruit flies, protein and salt proved most effective at triggering post-meal naps. The finding makes some sense: Meat and sodium have traditionally been harder to come by. And sugar, while it can disrupt long-term sleep patterns, was less likely to put the flies into a food coma, suggesting that the urge to pass out immediately after a hearty meal stems from a different set of hormones than those responsible for making you feel sleepy a couple hours after eating half of a pecan pie. This also points to evolutionary design, since sugar is less critical to long-term survival, but more important as a quick fuel source to use during hunting.

So bingeing on the turkey, gravy, and mayonnaise casserole (don't kid yourself about the smattering of green beans) may leave you snoring on the sofa come 4 pm, while those who gorge on pie and marshmallow-topped sweet-potatoes may want to throw the ball around all afternoon, only to toss and turn during normal sleep hours. And neither scenario is likely to leave you feeling rejuvenated, says Ja. "The sleep you experience after a large meal won't necessarily be deep or restful," he says. It's like alcohol: It may help knock you out, but it's unlikely to lead to to dreamland nirvana.

You want a strategy for skipping the post-meal crash? Of course you don't. You love that shit. But Ja has one anyway: Pace yourself. "Grazing slowly over a long period will keep you going compared to binge-eating quickly," he says.

Think of it this way: You're used to taking in something like 2,000 calories over the course of a 12-hour day. But on Thanksgiving, you eat 2,000 calories all at once. Your body reacts differently. The neuropeptides and hormones that your gut uses to communicate to your brain kick into overdrive, and as your stomach stretches to accommodate your second helping, nerve cells called nociceptors shoot out damage reports. You may experience these reactions as pain—the kind that makes you want to lie down and close your eyes.

Maybe you have a can't-stop-won't-stop mentality around food. As Louis C.K. once said: "The meal is not over when I'm full. The meal is over when I hate myself."

So maybe try not to reach that point? But if you do, at least you can drift out of consciousness until your self-respect returns.