It turns out that the gender of your dining companions makes a big difference in what you eat and how much you eat. The new research on dining habits — although small — adds a new dimension to the study of risk factors for obesity, and could also shed new light on eating disorders such as anorexia.
Both men and women appear to choose larger portions when they eat with women, and both men and women choose smaller portions when they eat in the company of men, according to new research published in the Journal of Applied Social Psychology.
The study, conducted among a sample of 127 college students, suggests that both men and women are influenced by unconscious scripts about how to behave in each other's company. And, these scripts change the way men and women eat when they eat together and when they eat apart.
Molly Allen-O'Donnell, then a graduate student at Indiana University of Pennsylvania, wanted to find out if what we eat is influenced by our peers. Allen-O'Donnell sat at a popular college eatery and observed how much food people purchased for lunch and dinner.
"I sat in a table so I could see what people were purchasing without really being intrusive," she said.
Allen-O'Donnell then observed whether students ate alone or with company. If they sat in groups, she counted the size of the groups. After asking permission from the people she'd observed, Allen-O'Donnell also documented whether people sat with friends or romantic partners, and whether or not they thought themselves overweight.
While multiple factors were correlated with how much people ate, Allen-O'Donnell and her co-authors found that the gender of people's dining partners seemed decisive.
When women sat with other women, for example, they ordered an average of 833 calories. When they ate with men, on the other hand, they purchased only 721 calories on average.
Allen-O'Donnell and co-author Marci Cottingham at the University of Akron said in interviews that they expected women would choose to eat less food when they ate in the company of men, since cultural norms in the West tell women to peck at their food in the company of men.
Prior research has suggested that women's beliefs about what constitutes appropriate eating portions in the presence of men could be responsible in part for eating disorders such as anorexia.
The surprise was the men – think of a group of guys holding back on the wings at a tailgate party or a Superbowl pigout. But when men sat with other men, they ordered an average of only 952 calories. When they sat with women, they ordered 1162 calories.
Allen-O'Donnell and Cottingham also acknowledged it was possible that unconscious scripts about how much to eat were at work when people sat down to a meal with someone of their own sex, not just when people sat down with someone of the opposite sex.
None of the participants that Allen-O'Donnell spoke with said they were aware that the gender of their dining partners affected how much food they purchased.
The point of the research, the researchers said, was to get people to realize that context mattered — even when it comes to food. Once people were aware that they could be unconsciously influenced in their dining choices, they might make eating decisions more deliberately.
DAVID GREENE, Host:
And Shankar, tell us what you're finding.
SHANKAR VEDANTAM: So actually what I want to do, David, is I want to conduct a quick experiment on you, if I could.
GREENE: OK. I'm game.
VEDANTAM: I'm going to use the magical radio to take you to two restaurants ...
GREENE: Sounds lovely.
VEDANTAM: ...where we have a guy sitting down in the first case with a woman and in the second case, with a bunch of his guy friends.
VEDANTAM: Here's what the first restaurant sounds like.
UNIDENTIFIED MAN: Would you care for a cocktail?
MAN: Would you bring me a bottle of your finest champagne, please?
MAN: Yes, sir. Very good.
GREENE: Sounds like sort of a stuffy date.
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VEDANTAM: All right. Now, we go on to the second restaurant. And here, he's sitting down with a bunch of his guy friends. Maybe they've come back from a ballgame or something.
UNIDENTIFIED WOMAN: Hi. You gentlemen ready to order?
MAN: I'll have a sirloin, medium; friend onions; baked potato with everything on it; and a beer.
VEDANTAM: All right, David. So here's the question. In one case, the guy's sitting with a woman. In the other case, he's sitting with other guys. Where do you think he's going to eat more?
GREENE: I guess if I'm that guy sitting with the woman getting champagne - I mean, I don't want to just get a salad but, you know, I don't want to overeat and seem like pig. So maybe, you know, a nice salmon filet. And if I'm sitting with my guy friends, I mean, it's got to be a burger - or two.
VEDANTAM: She sets up the experiment this way.
MOLLY ALLEN: I sat in a table close enough that I could see what people were purchasing, without really being intrusive.
GREENE: She's like a spy in a restaurant. I'm going to be looking out for people like her when I sit down to eat from now on.
VEDANTAM: That's exactly right. So she's spying on people. And she starts seeing all kind of interesting things. So she looks at a table with four guys, for example. And here's what she sees.
ALLEN: There was this one, specific case that I remember. There were four guys eating together, and they all ate salads. And I was just so shocked.
GREENE: That kind of shocks me, too. I mean, I can't remember a time when I'm sitting with my guy friends, especially after a ballgame, eating salad.
VEDANTAM: Right. So that's the stereotype we have. But Molly finds that when she crunches the numbers, that when both men and women sat down with men, they tend to eat a lot less than when they sit down with women. So both men and women eat a lot more when their dining companions are women. And they eat a lot less when their dining companions are men.
GREENE: A man or a woman - whoever it is - if you're sitting with a woman, you're eating more food?
VEDANTAM: That's exactly right. So, you know, the effect of women seems to be that both men and women order more food than they would have otherwise.
GREENE: I guess I will say - and this is probably going to get me in trouble with my wife, but she was just on a vacation in South America, and I was not eating regular meals. I was eating little bits and pieces - you know, ramen, or making a little sandwich. When she came back, I mean, we ate healthy, but we would have regular meals. And I felt sort of self-conscious if we didn't do that. So maybe I have been eating more since she got.
VEDANTAM: You really are going to get in trouble with your wife, David. I'm going to confirm that. But, you know, the truth is that when I got married, I put on a whole bunch of pounds as well. I mean, the bottom line here is, you know, we're responsible for the food we put on our fork, and the forks we put in our mouths.
GREENE: So, Shankar, I mean, we can think about our own experiences. But is there sort of a specific hypothesis for why a guy would be sitting there eating more with a woman compared to another guy, and why a woman would be eating more with a woman than she would be with a guy?
VEDANTAM: So, I mean, the truth is the researchers don't really know. They have theories about that. And their idea is that when guys are sitting down with women, they're acting out a script of what it means to be masculine. And what it means to be masculine is to be a carnivore, to eat a lot of food.
GREENE: Eat more, eat meat.
VEDANTAM: To eat more, yeah, and that women sitting down with men are acting out a script of what it means to be feminine. And that script, at least in our culture right now, is eat less, peck at your food, pretend that you're not really hungry.
GREENE: We should - hang on. This was just a study of college students. I mean, do we know that the same thing affects adults?
VEDANTAM: This was college students. These are heterosexuals. These are largely white. It's a small study. So, you know, the bottom line is: Context seems to matter when we sit down to eat. And the central idea behind the research is that once people become aware that the context they're eating with makes a difference, they can choose to eat what they eat, and how much they eat, a little bit more deliberately, a little more consciously.
GREENE: Interesting stuff, interesting conversation. We'll hope that our marriages both survive it.
(SOUNDBITE OF LAUGHTER)
GREENE: NPR science correspondent Shankar Vedantam. You can follow him on Twitter and Facebook at HiddenBrain. That's one word, HiddenBrain. And you can follow us at MorningEdition.
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LYNN NEARY, Host:
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