Louise Ma / WNYC
Source: Louise Ma / WNYC

I’ve never understood people who start their Sundays with a slice of the previous night’s cold pizza. Not because I find congealed, stale take-out food disgusting. It’s just that if I buy a pizza, I’m eating a pizza. I’m eating that pizza until there’s no more pizza left to eat. Until my stomach resembles a punched calzone.

But I also acknowledge that I am not normal. Most of you know when to call it a day. Maybe you're finished after three slices. Maybe you're finished after two. Maybe, if you’re a complete maniac, you claim to be full after a single slice.

Why is this? Does it all come down to appetite and metabolism? Is it merely a desire to preserve your dignity by not cramming another wedge of cheesy dough down your gullet like a happy pelican?

Or is it because of the company you keep?

It’s possible: A team of economists from Cornell University has found that the amount of food we eat depends on the gender of our dining partner.

Kevin Kniffin and colleagues visited an “all you can eat” restaurant where customers pay a set amount and are then free to consume as much pizza as they desire. The researchers kept a close eye on what the customers ate. At the end of the day, they had tallied up how many slices of pizza 74 men and 59 women had put away. They also kept track of the gender of each customer’s dining companions.

After crunching the numbers, the team found that men who dined with women ate significantly more pizza than men whose companions were all male.

Men in all-male groups consumed an average of 1.6 slices of pizza. Men accompanied by a woman ate almost 3 slices—a 93% difference! As for women, they downed an average of 1.3 slices when eating with men, and 1.1 when eating with other women, a difference that is not statistically significant.

Robert Burriss, modified from Nick Sherman/Flickr
Source: Robert Burriss, modified from Nick Sherman/Flickr

Why do men seem to get the munchies when they're around women? Kniffin reckons it’s because men like to show off:

“Sustained overeating most likely leads to body shapes that women do not typically consider to be attractive; however, in the context of short-term events (e.g., a single meal), it is plausible that overeating would be recognized as an attractive demonstration of strength and energy.”

The researchers pointed out that recent research by another team suggests that men may be especially keen to eat new foods around women because it advertises their strong immune systems. Also, when a man demolishes a double serving of pizza, he may be showing his date he has an iron constitution. Or that he’s unperturbed by the prospect of clogging his arteries and developing a spare tire that would fit a monster truck.

Incidentally, men’s overeating is not confined to fatty foods. Kniffin and his team found that men eat more salad when dining with women, too. A man eating with other men will eat 2.7 small bowls of salad; when he eats with a woman he’ll put away five. (Women appear to eat the same amount of salad regardless of the gender of their dining partners.)

Kniffin acknowledges that his data cannot tell us “whether the showing-off is a product of female mate choice or intrasexual competition among men." He suggests that an interesting follow-up experiment could be conducted at an eating contest:

“Future research that includes hormonal assays could test whether people who win eating contests tend to experience the kind of testosterone increases — and decreases — that researchers have found when people win — and lose — other contests (e.g., wrestling matches).”

Reference

Kniffin, K. M., Sigirci, O., & Wansink, B. (in press). Eating heavily: Men eat more in the company of women. Evolutionary Psychological Science. Read summary.

Facebook image: g-stockstudio/Shutterstock

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