A Woman’s Drive to be Thin May be in Her Genes

Many factors influence a woman’s self-perception of physical attractiveness. New research shows that genetics may also play a role in how some women gauge their body image. (Photo: Christine Tremoulet via Flickr/Creative Commons)

While cultural and societal factors have long been thought to influence how women see themselves in the mirror, a new study in Michigan has revealed that genetics may also play a role in making some women more vulnerable to the pressure of being thin.

Many people today, especially women, have taken the modern axiom, “Thin is In“ to heart.  So much so that a number of those pushing themselves to lose weight in order to become thin have developed serious problems such as the potentially deadly eating disorder, Anorexia Nervosa.

Women are constantly reminded by the media that it’s best to be thin.  From size-zero models to airbrushed film stars, thinness is portrayed as equaling beauty across Western culture. While both genders are subject to this pressure, it tends to fall harder on women for a variety of reasons. That skinny ideal can cause women to have a poor body image in the way they see themselves and imagine how they look.

Michigan State University researcher Jessica Suisman led a study that focused on the possible psychological impact of women who actually believe this perceived ideal of thinness, something the researchers called “thin-ideal internalization.”

Ms. Suisman and her colleagues gathered more than 300 female twins, from 12 to 22 years of age, from the Michigan State University Twin Registry, to participate in the study.  The researchers first made a measurement of the women’s “thin idealization” — or just how much their study subjects wanted to look like the thin women who are often shown on TV and in magazines.

In western cultures women are constantly reminded by the media that it’s best to be thin. (Photo: Helga Weber via Flickr/Creative Commons)

Once these measurements were made, the researchers then compared the genetics of identical twins, who share 100 percent of their genes, with those of fraternal twins who share 50 percent.

The researchers, examining the results of these measurements found that identical twins have a close to identical level of thin idealization than their fraternal twin cohorts.  To Suisman and her colleagues this suggests that genetics play a significant role in pressuring women to believe that they need to be thin (“thin idealization”).

As they continued their analysis of the data, the researchers found that the heritability of thin idealization is 43 percent, which they believe means that nearly half of the reasons women differed in their idealization of thinness can be explained by variations in their genetic makeup.

But Suisman pointed out that their research did not find a specific gene that makes a woman think, ‘I want to be thin.’  “That wouldn’t make any sense because we haven’t always had these thin models as our ideals,” said Suisman.   “We aren’t sure exactly what these same genes would have done many years ago or even in a different culture in the world where thinness isn’t seen as the equivalent for beauty,” she adds.

Suisman’s research team also looked at what environmental influences, such as friends, family, society and/or culture, were most important in determining how women felt about their bodies and how much they wanted to look like the ‘media ideal.’

A study led by Jessica Suisman, from Michigan State University, suggests that, for some women, genes may influence the pressure to be thin. (Photo: Michigan State University)

“And what we actually found was that environmental influences that were really specific to each individual woman, rather than the general environment was more important,” said Suisman.  In other words, individual experiences such as having friends and peers who are focused on thinness, or being involved in a sport that’s also focused on thinness, were more important and played more of a role in pressuring women to be thin than general societal and cultural influences.

“The take-home message,” Suisman said, “is that the broad cultural risk factors that we thought were most influential in the development of thin-ideal internalization are not as important as genetic risk and environmental risk factors that are specific and unique to each twin.”

Jessica Suisman joins us this weekend on the radio edition of Science World.  She tells us more about her research and findings and how genetics could play a role in pushing women to focus on being thin.

Check out the right column for scheduled air-times or listen now to the interview below.