Please could you explain what thin ideal internalization is?
Jessica Suisman: Thin-ideal internalization is the extent to which a person identifies with the cultural ideal that thinness is equivalent to attractiveness. Someone who has high levels of thin-ideal internalization would agree with statements such as, “I wish my body looked more like the bodies of women I see on TV and in magazines” or “I compare my body to the bodies of actresses on TV”.
What has traditionally been thought to cause people to feel pressure to be thin?
Jessica Suisman: Past research on the development of pressure to be thin has focused almost entirely on environmental and cultural influences. For example, cultural factors such as viewing images of thin women in media, experiencing pressure from friends and family to be thin, or experiencing teasing about body weight have been the focus of research on the causes of thin-ideal internalization.
Kelly Klump: Additionally, some theories have focused on the environmental transfer of concerns about thinness from the mother to the daughter by modelling, for example, by the daughter observing her mother’s behaviours and learning them from her. However, as this study points out, genetic as well as environmental influences play a role.
What psychological problems can the pressure of being thin cause?
Jessica Suisman: Thin-ideal internalization can lead to an array of psychological problems, including poor body image, dissatisfaction with one’s body, and severe dieting. This can lead to even more serious problems, such as an eating disorder like anorexia nervosa or bulimia nervosa. By better understanding the causes of thin-ideal internalization, it is hoped that eventually, we will be better able to prevent the development of these disorders.
How did you research into thin ideal internalization originate?
Jessica Suisman: We became interested in the potential importance of genetic influences on thin-ideal internalization when we noticed that despite wide cultural pressure to conform to ideals of thinness, only some women actually feel pressure to meet this ideal. We wondered whether women with genetic vulnerabilities might be more likely to develop thin-ideal internalization than women without these genetic vulnerabilities. In other words, we thought that genetic differences might partially explain why some women can “brush off” media images of very thin women, while in other women, seeing these images results in intense feelings to also look very thin.
Additionally, past research has established that genetic influences are important in the development of eating disorders and symptoms of eating disorders, as well as other psychological traits and disorders, including depression and anxiety. We thought that genetic influences might be similarly important in the development of thin-ideal internalization.
What did your research involve?
Jessica Suisman: We examined whether genetic influences are important in the development of thin-ideal internalization by comparing thin-ideal internalization in identical twins, who share 100% of their genes, with fraternal twins, who share 50% of their genes. The study included over 300 twins from the Michigan State University Twin Registry who were between the ages of 12-22.
We measured thin-ideal internalization by asking participants to complete a questionnaire about the amount that they compare their bodies with media images and try to make their bodies look like women that they see in the media, such as on television or in magazines. We then compared the similarity of responses on this questionnaire in identical twin pairs versus fraternal twin pairs.
Did your research look at thin ideal internalization in both males and females?
Jessica Suisman: For the current study, we only included a sample of adolescent and young adult women. However, eating disorders and symptoms of eating disorders are also problems that men suffer from, and some research suggests that the rate of eating disorders in men has increased in recent years. Future research on this topic that includes men will be especially important in understanding similarities and differences in the development of eating problems in men and women.
What did your research find?
Jessica Suisman: Findings suggested that identical twin pairs have more similar levels of thin-ideal internalization than fraternal twin pairs. In other words, identical twins had more similar answers to each other on the questionnaire than did fraternal twins. This pattern of results suggests significant genetic influences on thin ideal internalization, since identical twins share a larger proportion of their genes than fraternal twins. Statistical models suggested that 43% of the differences among individuals in thin-ideal internalization can be explained by genetic influences.
Importantly, we ensured that the more similar levels of thin-ideal internalization in identical twins could not just be due to identical twins having more similar body types than fraternal twins. We did this by measuring each participant’s height, weight, and body mass index, and accounting for differences between twins’ body size in our statistical analyses.
Importantly, our findings do not suggest that the environment, such as exposure to media, is unimportant. Instead, this research suggests that genetic influences may impact how people respond to the environment.
What impact do you think your research will have?
Jessica Suisman: Thus study was an initial step in understanding how genes and the environment contribute to thin-ideal internalization. We hope to continue to use twin designs to examine whether the genetic influences that are important for thin-ideal internalization are the same as genetic influences that affect eating disorders. Eventually, we hope that by thoroughly investigating risk for thin-ideal internalization, prevention efforts aimed at forestalling the development of eating disorders will improve.
Kelly Klump: We also hope to increase understanding of the complexity of eating disorder risk. That is, not just one factor (e.g., the media) causes eating disorders, but many genetic, social, and psychosocial risk factors all come together to increase one’s risk for developing thin-ideal internalization as well as eating disorders.
Do you have any plans for further research into this area?
Jessica Suisman: We are currently using twin studies to examine if the same genes that influence thin-ideal internalization also influence eating disorders. We are also hoping to investigate whether certain personality traits, such as being a perfectionist, share genes with thin-ideal internalization.
Would you like to make any further comments?
Jessica Suisman: It is important to note that our study did not examine specific genes that may be related to thin-ideal internalization. Twin studies of this sort can only indicate the magnitude of genetic effects, not the specific genes involved. It is likely that small effects of many genes cause the type of genetic risk that we observed. It is well established that a range of influences (i.e., genetic, biological, environmental, psychological) contribute to the development of eating disorders, and these same factors should be considered for thin-ideal internalization.
Where can readers find more information?
Full text of journal article: http://onlinelibrary.wiley.com/doi/10.1002/eat.22056/full
MSU Twin Registry: http://msutwinstudies.com/
About Jessica Suisman and Kelly Klump
Jessica Suisman, M.A. is an advanced graduate student in clinical psychology at Michigan State University. She completed her master’s degree in 2010 and she expects to complete her doctoral degree in May, 2014. She has been working on research investigating the interactions between genetic, biological, and environmental influences on eating disorders since 2005.
Kelly L. Klump, Ph.D., FAED is a Professor in the Department of Psychology at Michigan State University. Dr. Klump received her B.S. in Psychology from Michigan State University, and her Ph.D. in Clinical Psychology from the University of Minnesota. She completed her pre-doctoral, clinical internship at McLean Hospital, Harvard School of Medicine, and her postdoctoral fellowship at Western Psychiatric Institute and Clinic, the University of Pittsburgh School of Medicine. Dr. Klump’s research focuses on genetic and biological risk factors for eating disorders. She is particularly interested in developmental changes in these risk factors and their meaning for the development of eating disorders.