DAVID GREENE, Host:
It is alarming how obesity is rising in the United States. We know the usual culprits: junk food, too little exercise - you know the drill. But new research suggests there might be another hidden factor - gender. NPR science correspondent Shankar Vedantam joins me to discuss some new insights into human behavior.
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: Yeah. So that's what I would've guessed as well. But I actually want to show you what some recent research has found. This was just published in the journal of Applied Social Psychology. The experiment is taking place at Indiana University of Pennsylvania. And there's this graduate student, Molly - Molly Allen-O'Donnell. And she's decided she wants to snoop on her fellow students as they're eating, and watch how much it is they're eating.
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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