Skinny Genes: Could Heredity Raise Your Vulnerability to 'Be-Thin' Pressure?10/03/12
WEDNESDAY, Oct. 3 (HealthDay News) -- In a culture that
frequently projects the message that you can never be too thin, a
new study says genetic factors may make some women especially
susceptible to that ideal.
Almost half of the reason some women are more likely to succumb
to the pressure to be lean can be explained by differences in their
genetic makeup, the new research suggests.
Some women may essentially have two risk factors: They are
innately predisposed to want to be thin, and also have family
members, friends or activities reinforcing thinness as an ideal,
according to the study.
In other words, it's not the culture of fashion magazines, TV
and film that's really the problem for women who are genetically
most susceptible. Rather, for these teens and young women, their
buddies, a dance class or parents who periodically call them plump
compound the problem.
"Basically, we vary in how permeable we are to environmental toxins -- including media pressures about the thin ideal -- and that variation can have its roots in genes," said Cynthia Bulik, director of the University of North Carolina Eating Disorders Program, in Chapel Hill. She was not associated with this study.
The study, based on data from 2008 to 2012, examined genetic and
environmental influences on what the researchers call "thin-ideal
internalization," social reinforcement by people the women respect.
Internalizing the "be-thin" messaging is considered a risk factor
for body-image disturbances and eating disorders.
The need to be thin isn't absorbed from the larger culture by
everyone, Bulik said.
"Why do some girls or women -- and even boys and men -- see a Photoshopped image or hear an advertisement that urges them to become dissatisfied with some aspect of their physical appearance and totally brush it off, whereas others go to the mirror, perform a self-evaluation, take it onboard, become self-critical, experience a plummeting of their mood and engage in disordered eating behaviors to try to correct the manufactured flaw?" she asked.
The study, published in the
International Journal of Eating Disorders, involved sets of
twins from the Michigan State University Twin Registry.
Participants included nearly 350 females aged 12 to 22; all were
born in Michigan and 80 percent were white.
The researchers measured how much the participants wanted to
look like people in film, TV and magazines to gauge their level of
"thin idealization." Identical twins (who share 100 percent of
their genes) were compared to fraternal twins (who share 50 percent
of their genes).
Identical twins had more similar levels of "thin idealization"
than did fraternal twins, the research found. That suggests that
genes play a role in explaining the differences between the two
types of twins, the study authors said.
The study suggests that the "heritability" of thin idealization
is 43 percent, meaning that almost half of the reason women are
more prone to idealize thinness may be due to genetic differences,
the researchers said.
The study, however, was not designed to determine a
cause-and-effect relationship between genetics and thin
idealization, but rather only a link.
"Some people have a genetic propensity to internalize these ideals," said Jessica Suisman, a study co-author and graduate student at Michigan State. "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."
Suisman advises women who realize they idealize thinness to try
to participate in social and leisure environments that put less
emphasis on being lean.
"Listen for it, and avoid having some of the negative thoughts about your own body," she said. In other words, women should tell themselves they are OK as they are.
The researchers would like to expand the study to a larger
number of participants with broader ethnic and cultural
backgrounds, Suisman said.
"We'd also like to know if the genes affecting the risk of internalizing thinness are the same or similar to those that affect eating disorders," she said. "And we'd like to analyze personality traits -- such as perfectionism and high levels of emotion -- to see how those factors may be involved."
Visit the U.S. National Institute of Mental Health to learn more
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