By Randy Dotinga
HealthDay Reporter

THURSDAY, Aug. 9 (HealthDay News) -- New research suggests that stress makes men more likely to be attracted to slightly heavier women, possibly because evolution has programmed them that way.

The study is small -- it tracked just 81 male college students -- and far from definitive. Still, it "suggests that stress alters what you find attractive in a potential partner," said study co-author Martin Tovee, of Newcastle University's School of Psychology in the United Kingdom.

At issue is how men figure out whom they're most attracted to. According to Tovee, standards of beauty don't just change over time but also from place to place.

"For example, our work in parts of Malaysia and Africa has shown that in poorer environments where resources are scarce, people prefer a heavy body in a potential partner," he said. "If you live in an environment where food is scarce, being heavier means that you have fat stored up as a buffer against a potential reduction in food in the future and that you must be higher social status to afford the food in the first place."

But people in richer countries, such as the United States, have different preferences about their mates, he said. "This suggests that our body size preferences are not innate but are flexible and can be changed by environment and circumstance."

In a previous study, Tovee and colleagues found that hungry students are more attracted to heavier people. In the new study, researchers looked at stress, "another factor that is likely to be high in a poorer environment," he said.

The researchers recruited 81 white males for their study. They were all white. because ethnicity can throw off the results, and aged 18 to 42. Of the 81 participants, the researchers exposed 41 to stress: they had to act like they were in a job interview in front of teams of men and women, then they were told to continually subtract 13 from 1,022 as fast and accurately as possible.

All the men then ranked the attractiveness of women in photos.

The researchers found that the men whom they'd attempted to stress out preferred a heavier body size. The difference was "small but significant," Tovee said.

The study authors theorize that evolution has programmed men to adapt their preferences about mates for the current situation, recalibrating them as things change. However, they caution that the study has weaknesses -- such as the inability to have a true understanding of how stressed the 41 men actually were. Also, the study did not look at the reverse situation -- how women view men.

Steve Gangestad, a professor of psychology at the University of New Mexico, said there may be another explanation for the effect seen in the study. The stressed men "may have suffered a temporary blow to social self-esteem," he reasoned. "Perhaps, then, this is the reason men in that condition were less rejecting of body types that, given Western norms, are generally less preferred."

Gangestad said more research will provide better insight into what's going on.

Why does this research matter? In the big picture, "this research is important as we need to understand the factors shaping body preferences," Tovee said. "People suffering from conditions such as anorexia have a distorted perception of body size and body ideals, and it important that research focus on the mechanisms underlying and influencing the perception of body size. It is also important to understand how stressful changing environmental conditions -- such as rapid industrialization in the developing world -- may alter peoples' body shape preferences and ideals and the health implications for these changes."

The study appears in the August issue of the journal PLoS One.

More information

For more about stress, try the U.S. National Library of Medicine.

Copyright © 2012 HealthDay. All rights reserved.