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.