Aug. 9, 2012 -- Gentlemen may prefer blondes, but stressed men prefer heavier women -- at least according to a new study.

In this study, published Wednesday in the journal PLoS ONE, researchers at the University of Westminster in London subjected 41 men to a stress-inducing task. After this task, the researchers asked the men to rate the attractiveness of female bodies ranging from emaciated to obese.

Compared to a control group of 40 men who did not undergo the stress task, the stressed men rated a significantly heavier female body size as the most attractive, and they rated heavier female bodies as more attractive in general.

"Our body size preferences are flexible and can be changed by environment and circumstance," explains Martin Tovee, one of the study's authors. "We need to understand the factors shaping body preferences."

In this case, it appears that stress alters the classic stereotype that men prefer thin women in general.

Researchers not directly involved with the study said the finding is consistent with what past work has shown regarding the way stress influences our perceptions.

"Stress, both acute and chronic, has profound effect on how we process new information both cognitively and emotionally," explains Dr. Igor Galynker, associate chairman of the department of psychiatry and behavioral sciences at Beth Israel Medical Center.

In fact, earlier research has shown that men also prefer heavier body sizes when resources are unpredictable or unavailable. Certain evolutionary theories suggest this may be because when times are tough, a thin woman may be ill, have irregular periods, and may be unable to support pregnancy.

"If you live in an environment where food is scarce, being heavier means that you have fat stored up as a buffer and that you must be higher social status to afford the food in the first place," Tovee explains. "Both of these are attractive qualities in a partner in those circumstances."

The study also found that the stressed men gave higher ratings to a wider range of female figures than did their unstressed counterparts. This may have implications about how we choose the people to date and marry. For example, do men in high-stress jobs look for overweight mates, or are their standards lower?

"In this case, mate selection criteria may become more liberal as a way of preserving the species," explains Scott M. Bea, clinical psychologist and assistant professor of medicine at the Cleveland Clinic. "We have some proverbs that reflect this idea such as, 'Any port in a storm.'

"This is probably not just true of physical attractiveness or mate selection. For instance, if one is homeless, we might accept lodging that others would view as inferior."

As for how this research might be useful, understanding how different factors influencing peoples' body shape preferences and ideals may prove valuable in the treatment for body image disorders. After all, if body shape preferences are flexible, thinness may not be the ideal body type that we think it is.

"The information from this article could be useful in therapy of anxiety and eating disorders," Galynker says.

"The information could be an alternative to thoughts such as, 'I am fat; no man would find me attractive.'"