If you’re planning to lie about your weight on an online dating site, you’d be well advised to shade downward if you’re a woman and (more surprisingly) upward if you’re a man.
That’s one apparent lesson of the data in this recently published paper by three careful researchers. If I’m reading their tables correctly, they say roughly this:
Taking as given your reported age, height, race, weight, income, attractiveness, education, marital status and so forth, there is some class of users who have about a 50/50 chance of contacting you. Now if you are a 5’4″ woman and you subtract 11 pounds from your reported weight (lowering your body mass index, or BMI, by about 1), then you’ll hear not from 50% of that class but from almost 60%. On the other hand, if you are a 5’10” man and you *add* 7 pounds to your weight (adding about 1 to your BMI), you’ll hear from about 53%.
Moreover, these effects fall off very slowly, so that even very thin women gain from underreporting their weights, and even very heavy men gain from overreporting. The effects also fall off very slowly with BMI differences, so that even quite heavy men prefer thinner women, and even quite thin women prefer heavier men.
This isn’t the question the researchers set out to study. Their real goal was to understand why we tend to marry people very like ourselves—is it because we prefer those people, or is it because those are the people we tend to meet? Roughly, their conclusion is that online and offline daters have pretty much the same tendency to seek others like themselves, which suggests that the driving force is preference, not search cost. But this odd fact about weight fell out of the data along the way, and it strikes me as puzzling enough to ask my readers what they think is going on here.
A hat tip to Robin Hanson, who noticed this curiosity before I did, and to my very thin friend Elizabeth Boskey for the title.
Off-the-top-of-my-head thought:
For women, increased weight is a marker for “unlikely to [be able to] stray” because other women don’t REALLY want fat men. So fat, unattached men are attractive to women because fat, attached men really aren’t. It’s sort of like why nerds are attractive in the age of AIDS. Women want them because they’re disease free because women don’t really want them…
Perhaps the explanation is as follows: For a man, your headshot establishes how fat you actually “look”, so if you inflate your weight relative to your headshot, women will assume the extra weight is muscle. But if a woman inflates her weight relative to how she looks in the pictures, men will assume the extra weight is body fat that she’s artfully hiding in the pictures.
“why we tend to marry people very like ourselves—is it because we prefer those people, or is it because those are the people we tend to meet?”
Isn’t it also possible that we prefer people *better* than those we end up with, but given our own qualities, they are the best mate we can buy?
Maybe what women value most is honesty. And in these times when being overweight is looked down upon, people might be expected to not report that they are overweight. Hence someone who does report that they are overweight will appear more honest. So, ironically, by lying about your weight by claiming to be heavier than you are, you might appear even more honest.
Perhaps the majority of women on these sites are overweight and feel like they would have a greater chance of success with an overweight man. Similarly, the majority of men are interested in women who look good in bikinis and aren’t as put off by their own possible shortcomings.
Perhaps women perceive heavier men as more convivial, which might imply contentment and satisfaction with life. A leaner man might seem more aggressive or withdrawn with the implication that he is not content with his status and therefore a difficult potential partner.
Most of the comments made so far are by men (like me) and it is interesting that the general tone is slightly hostile to this report. Could this be because it raises a challenge to our egotistical view of what ought to be attractive to women? We feel that strength, size and aggression are important, whilst a woman is perhaps more likely to emphasize the value of kindness and sociability.
Do we now have license to eat and drink as if there were no tomorrow?
Suppose that people do want someone similar to themselves. Now suppose that there is an equilibrium where women all shade 10 lbs. from their weight. An average weight woman who responds honestly will then be perceived because everyone knows that the typical woman shades 10 lbs. So, she has to make the cut just to be believed. Meanwhile, the men know that the women who respond are heavier than their reporting suggests, so they prefer to go for a heavier fellow who will be less likely to walk away over her weight shading (throwing stones from a glass house and all). Thus, if the men respond with their true weight, then the women may respond less because they fear wasting time on a svelte man who they feel may walk. Once it is an equilibrium, the men would know that if they don’t add the weight, they will be perceived as lighter than they actually are.
Has the finding been replicated? Maybe its just a quirk.
I haven’t read the paper but does it mention, what sort of relationship the women were looking for? Do women looking for casual relationships and those looking for a long term partner both prefer heavier men?
If ErikK’s explaination is correct then wouldn’t it also apply to level of education and income? Do women prefer men with a lower level of educational attainment or a lower income?
I suspect that Rob’s answer is nearest the truth, but only for women looking for a long term partner. Women looking for a long term partner see extra weight as a sign that the man is more likely to commit to a long term relationship. I guess that women looking for a more casual relationship will show less preference for heavier men. Was this tested in the paper? Also it would be interesting to see if women in committed relationships with heavier men are more or less likelier to be unfaithful. I guess that they would be, and also that the men they are unfaithful with would be on average thinner than their long term partner. It would be interesting to test these hypotheses.
If men prefer women to be less heavy than they are and women prefer men to be heavier than they are, which is not hard to believe, then it follows from the sizes of the choice sets. For every pound a woman understates her weight there are more men heavier than she is to respond, and likewise when men overstate their weight there are more women less heavy to respond.
Women might like a higher BMI if it comes from muscle and strength. Terrell Owens probably has an overweight BMI, for instance.
Men don’t want high BMI fat women or high BMI muscular women.
If the study used body fat percentage instead of BMI, we’d probably see results that are less surprising to us.
How do you know the women are not looking for wallet size? Rich men are heavier.
Perhaps women find very thin men unattractive, and thus very thin men over report their weight. This could be tested by correlating the amount of over reporting to actual weight.
Probably there is not a single cause of men over reporting their weight, but a conjunction of multiple factors.
huh. Fascinating. In general, this would seem to play directly into widely held stereotypes about women being pressured to be thin and men being “allowed” to be heavier.
Here’s a thought: maybe women want a man who is substantially heavier than they are. So if you report your weight as a bit higher than it really is, then the gap between our weights will be larger, and that might be attractive.
If I were the kind of girl who cared about that. Which I’m not.
Erm… what Pat said. Heavy != fat. I have an overweight BMI as does, for example Jonny Wilkinson. I don’t think anyone would be surprised to find out that women are attracted to him.
Another “here, here” for Pat’s answer. BMI is really a poor indicator of body fat. Most professional athletes are overweight or obese according to standard BMI thresholds, because BMI doesn’t distinguish fat from muscle.
Sierra:
If I were the kind of girl who cared about that. Which I’m not.
I’ll stop force feeding myself then.
Pat, John, Glen:
What you said is both true and completely irrelevant to Steve’s post.
(Bennett’s related comment is intriguing.)
Bob, it’s clearly not *completely* irrelevant to Steve’s post. Steve says ‘men get more dates if they report being heavier’ we say ‘being heavier doesn’t mean being fatter’.
Now it’s possible that the numbers in the article preclude this as a plausible explanation, but maybe women prefer heavier men because heavier men have more muscle, and women are attracted to muscular men. Nothing in Steve’s post rules this out, and I haven’t read the article yet.
John: Fine, I retract the “completely”.
In this spirit, I would like to respond to Steve’s post by saying that I consider it deplorable to start off a relationship with a lie. And that Elizabeth Boskey’s creativity is not necessarily related to her weight.
The title of this entry is the same as the subject line of many spam emails that I get.
Having read the post but not the paper, I offer the following possibilities based on some stereotypical assumptions:
1. Average people are more likely to gain as opposed to lose unhealthy pounds as they age (except for the very oldest), and this effect might be greater for females.
2. Typically, both the male and the female prefer that the male outweigh the female member of the relationship.
The female has decent information on whether she is or is not the type to undertake the sustained effort to maintain her fitness as she ages. For the exceptional female, the answer might be yes. But for the typical, perhaps the answer is no. So a female who is not planning to undertake this effort may prefer a male with washboard abs if she is looking for a fling; but might prefer a male who significantly outweighs her for a long term relationship. This gives her a nice cushion of potential pounds she can gain over time before there is danger of her overtaking her mate.
Males of course are subject to weight gain as well, but they would rather the reason they remain the heavier partner be because the female did maintain her fitness. They also know that females are likely to gain unhealthy weight over time, and have little to lose by having the female start out lighter if possible (so the pounds she does gain are less likely to take her into the range he finds unattractive).
Ideally, people would take the effort to maintain their fitness well into old age, which is possible with a lifetime of choosing “use it” over “lose it.” Those who are planning to “lose it” might free up some of their time in the short run by skipping the gym, yoga, and karate practice, but the costs may include some unhappy compromises elsewhere in life.
(It might be pointed out that under this hypothesis, males have less to lose in the dating game by “losing it.” That might be true relative to females, but it is not sufficient to show that he is better off “losing it.” He may prefer the longer life that fitness can afford him, and he may be trying to improve his chances with the excptional females who are also set on using it. Females, on the other hand, should be better off on all counts (except the time cost in the short run) by using it.)
BMI isn’t necessarily a proxy for fatness; it’s a proxy for frame size too. Every girl wants to date a guy that’s bigger than she is–in height and in frame size. Being beefy–or at least physically larger– is masculine. Guys, in turn, want not only a thin woman, but wish to have a girl who is smaller than he. My female friends have told me that they’d never date a guy smaller than they are; it makes them feel an uncomfortably more masculine role. I, in turn, would never date a woman who was larger than me, unless she had really good features that compensated. It just looks silly to be with a girl that’s bigger than you. It’s not just height; overall perception of size is the key–and BMI is sensitive to overall size.
Note from the OB post, that this is weight controlling for attractiveness and everything else. The result could be a result of collinearity between these regresors. It’s not surprising that of two men who are equally attractive, a larger man might be preferred. Being large is impressive.