By Lisa Collier Cool
Nov 29, 2012
Nov 29, 2012
Day
in Health
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Guys—size matters, but not in the
way you think. Women are drawn to men with low body fat—not macho features,
such as a manly jaw or six-pack abs, according to a surprising new study
published in Proceedings of the Royal Society B:
Biological Sciences. Overall, the guys women rated as
most attractive had about 12 percent body fat.
Intriguingly, the scientists also
found that men’s antibodies, not hard bodies toned by long hours at the gym,
are what turn fertile women on. From the evolutionary point of view, that makes
sense, since a woman would choose a mate with optimal genes and a healthy
immune system to father her kids.
But how can women tell at glance
which men have these desirable traits? Here’s a closer look at the research.
Is
There a Link Between Testosterone and Hotness?
Scientists used to think that a
macho appearance would be an evolutionary asset for men, based on the
“immunocompetence handicap hypothesis.” This theory holds that a highly
masculine appearance indicates that a man have overcome the “handicap” of
contending with the negative effects of having high levels of the male hormone
(which makes men more susceptible to infections).
Therefore, proponents of this theory
believed that a manly appearance should be highly alluring to women, as an
indication of “good genes.” In other words, a man needs to be very fit and
healthy to overcome the so-called testosterone “handicap.”
Yet studies show that women don’t
consistently prefer the most masculine-looking men, nor are macho looks always
linked to better health in men across studies. Body weight, however, is
strongly associated with both a robust immune system and good health, with both
very overweight and very underweight men at greater risk for medical problems.
Investigating
the Secret of Men’s Sex Appeal
To find out what makes a man most
likely to be a babe magnet, the researchers recruited 69 young white men of
varying appearances and weights. All of the men were photographed in what the
researchers call “standardized underwear” and their body fat percentage was
measured.
Almost two-thirds of the men were of
a normal weight, four percent were underweight, and the rest were overweight or
obese. The men also underwent blood tests to check their levels of circulating
testosterone and antibody levels before and one month after getting a hepatitis
B vaccination.
Twenty-nine young heterosexual women
who were in the fertile phase of their menstrual cycle (and not taking birth
control pills) were asked to rate the sexual attractiveness of each man’s face
and body. The photos were also rated by a separate panel of 20 heterosexual
women on the men’s degree of masculinity of the man’s appearance. A third group
of women evaluated how fat or thin the men’s faces were.
The ratings were then compared with
the men’s testosterone and hepatitis B antibody levels one month after the
vaccine to identify men with the healthiest immune system response.
What
Really Makes a "Babe Magnet"
Contrary to what the
immunocompetence theory would have predicted, the researchers found no
correlation between a man’s masculinity rating and how sexy women found
him. Nor did the macho-looking men have a stronger immune system response to
the hepatitis B vaccine. And their levels of testosterone weren’t any higher
than those of men with a less manly appearance.
Instead, the women swooned over guys
with low body fat, with men who had 12 percent body fat being deemed the most
attractive. Slimmer men also had a more robust immune system. There was a link
between weight and testosterone, with higher levels found in thinner men.
“We found that a man’s weight serves
as a better indicator of the relationship between immune response and
attractiveness than masculinity does,” University of Pretoria researcher Vinet
Coetzee told LiveScience.com.
Coetzee theorizes that women use weight, rather than macho features, to
subconsciously make hot-or-not judgments about the men they meet.
This research, Coetzee added,
"serves as a stepping stone for future studies that could test this
relationship in different populations using alternative measures of
immunity."
The researchers also created two
intriguing composite photos, one with the combined features of of the eight men
with the weakest immune systems and another with the combined features of the
eight with the healthiest. Which guy do you think is hottest?
Above: Composite images of men with
low and high immunity. On the left is a composite image of the eight men with
the lowest antibody response in the study. On the right is a composite image of
the eight men with the highest antibody response in the study.
