Last updated: Jun 10, 2016

If you believe the evolutionary theory of attraction, what humans really want is to find a mate who can help them produce healthy, fertile offspring. (And here, you could have sworn that you wanted a guy who could match your passion for social justice and obsession with Game of Thrones. Oh well!)

But let’s keep going: From an evolutionary perspective, it makes sense that men and women want to partner up with people who have healthy-looking bodies—including ones with a healthy amount of body fat. Right?

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Well, researchers from Macquarie University in Sydney, Australia, have some interesting news on that theory. When they asked 63 students (male and female) to manipulate images with a computer program to design the most attractive male body, the participants chose figures with a healthy amount of fat and muscle (as the researchers predicted). But when the participants were asked to design the most attractive female body, they consistently chose figures with levels of body fat lower than the healthy range.

These findings, published in the journal PLOS One, surprised the researchers: “What is perceived as healthy and attractive should be in line with what actually is physiologically healthy,” study co-author Ian Stephen, PhD, said in an email to Health.

That’s because body fat is super important for women. Females need more fat than men do because we need a certain amount of fat to ovulate, carry a baby to term, and breastfeed, as the authors point out.

But the study revealed another interesting fact: When participants were asked to design a healthy-looking female body (as opposed to just attractive), they also picked images of women who were “underfat,” as Stephen put it, though less so. From an evolutionary standpoint, that’s odd. And in terms of societal beauty standards, it’s depressing. 

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We should point out, however, that the people doing the judging in this study were all first-year white undergrads from an urban, affluent region of Australia.

So while it’s possible that Aussie psych-students prefer svelte mates (sorry, couldn't resist), there might be another explanation for the study’s findings. Stephen suspects the body weight preferences are “responses to ecology.”

He pointed out in poor, rural communities around the world where there is significant food insecurity and high risk of disease, larger bodies are considered attractive. “Being fatter may then be healthy in these regions, as both starvation and disease tend to cause weight loss,” he explained. But in wealthy societies, obesity is a bigger health risk than being skinny, and there are vastly more people who suffer negative consequences from having too much body fat than too little. “Thinness in wealthy, urban societies therefore can be a sign of health.”

That's one theory. Or there's what we call the "Jennifer Lawrence Theory" (which we admit, we just made up). J.Law notes that the media so often portrays underweight women, that it skews reality for the rest of the world. So maybe that's why this study found that both men and women have come to equate "attractive" with "too thin." You decide.