Author: Benthe Geerdink

The nature versus nurture consideration has been around since the time of the ancient Greeks. Since then, people have continued to debate whether certain phenomena – especially behavioral patterns and disorders – are a product of biological factors or whether they are produced through nurture, which includes external factors like life experiences and a person’s environment (MedicineNet 2019). When examining the causes of eating disorders, the nature versus nurture debate gives us an interesting starting point.

Nature

In 2007, a twin study which isolated the role of genetics found that roughly half of the risk for anorexia nervosa, bulimia nervosa, and binge eating disorder can be attributed to genes (Klum et. al. 2007). A further study extends these insights, concluding that individuals who have someone that has suffered from an eating disorder in their immediate family are 11 times more likely to develop one themselves (Strober 2000). The genetic link of eating disorders becomes even more evident in the case of identical twins. Here, researchers found that when one twin developed an eating disorder, their genetically identical counterpart had a 60 percent chance of developing one too (The Active Times 2016).

This does not mean however, that there is one specific “eating disorder gene” that one either has or does not have. Rather, people inherit certain susceptibilities that are associated with the development of eating disorders. In 2017 for example, a landmark study found that one genome, namely chromosome 12, contributes to the development of anorexia nervosa. This region on chromosome 12 has also been shown to be associated with Type 1 diabetes, autoimmune diseases, and further mental health disorders such as neuroticism and schizophrenia (Bulik et. al. 2017). The study also revealed high genetic correlations between anorexia nervosa and metabolic factors such as body mass composition and insulin-glucose metabolism (Bulik et. al. 2017).

Additional genetic susceptibilities include lower levels of dopamine or serotonin in the brain, which regulate our moods, feelings and happiness (Garber 2020). In fact, for Bulimia patients, there was a significant correlation between low levels of serotonin and high amounts of binge-eating episodes (Jimerson 1997).

Nurture

However, being at risk of developing an eating disorder genetically does not mean you are guaranteed to get one. Instead, there are also environmental factors at play. 

In many countries like The Netherlands, the media perpetuates standards of beauty which encourage women and girls to be very thin (MacNeill and Best 2015). More than 75 percent of female fashion models registered at the 25 most important Dutch modelling agencies have a waist size that is smaller than what The Netherlands Nutrition Center considers to be healthy (Duijst et. al. 2018). People are regularly exposed to these body standards through various kinds of media like magazines, television, web shops and social media. The pressure of achieving this body can drive people to develop eating disorders (Healthwise Staff 2019).

Being in environments which emphasize a certain body type can also drive individuals to develop an eating disorder (Healthwise Staff 2019). This is the case for ballet dancers and gymnasts, for example. In fact, eating disorders were found to be ten times more common among ballerinas than among non-dancers (Shoker 2013). 

It is not only the consistency of a potentially harmful environment that increases the risk of eating disorders. Sudden changes in someone’s environment such as school transitions, the death of a family member or the experience of abuse, followed by a lack of needed support during these transitions, may also put individuals at risk (Berge et. al. 2013).

So is it Nature or Nurture?

There is no one-size-fits-all approach when it comes to eating disorders. For some individuals, their genetic predisposition might be the primary cause for developing an eating disorder. For others, a single traumatic event or long-term exposure to a harmful environment could be the inciting factor. Regardless of the initial cause however, what we know for sure is that recovery is reachable for all who seek it.

References:

Berge, J.M., K. Loth, C. Hanson, J. Croll-Lampert and D. Neumark-Sztainer (2012). “Family Life

Cycle Transitions and the Onset of Eating Disorders: A Retrospective Grounded Theory Approach.” Journal of Clinical Nursing 21(9-10): 1355-363.

Bulik C.M. et. al. (2017). “Significant Locus and Metabolic Genetic Correlations Revealed in Genome-Wide Association Study of Anorexia Nervosa.” American Journal of Psychiatry 174(9): 850-858.

Duijst, J., S. Yücel and W. de Jong (2018). “’Het Is Óf Afvallen, Óf Stoppen Met MijnModellencarrière’.” NOS Op 3. At https://nos.nl/op3/artikel/2248575%09het-is-of-afvallen-of-stoppen-met-mijn-modellencarriere.html.

Garber, N. (2020). “Neurotransmitters and Bulimia: What Does the Research Say?” Eating Disorder Hope. At https://www.eatingdisorderhope.com/information/bulimia/bulimia-and-the-brain-how-is-neurobiology-a-factor/research-on-bulimia-and-neurotransmitters. 

Healthwise Staff (2019). “Eating Disorders: Cultural and Social Factors.” HealthLink BC. At https://www.healthlinkbc.ca/health-topics/hw47995.

Jimerson, D.C. (1997). “Decreased Serotonin Function in Bulimia Nervosa.” Archives of General Psychiatry54(6): 529-534.

Klump, K.L., S.A. Burt, M. McGue, and W.G. Iacono (2007). “Changes in Genetic and Environmental Influences on Disordered Eating Across Adolescence: A Longitudinal Twin Study.” Archives of General Psychiatry 64(12): 1409. 

MacNeill, L.P. and L.A. Best (2015). “Perceived Current and Ideal Body Size in Female Undergraduates.” Eating Behaviors 18: 71–75. 

MedicineNet (2019). “Nature vs. Nurture: Effects on Genes, Mental & Physical Health.” MedicineNet. At https://www.medicinenet.com/nature_vs_nurture_theory_genes_or_environment/article.htm. 

Shoker, S. (2013). “Ballet and Eating Disorders: ‘Unspoken Competitiveness’ Adds Pressure to Be Thin.” BBC. At https://www.bbc.com/news/uk-england-22985310. 

Strober, M (2000). “Controlled Family Study of Anorexia Nervosa and Bulimia Nervosa: Evidence of Shared Liability and Transmission of Partial Syndromes.” American Journal of Psychiatry 157(3): 393–401. 

The Active Times (2016). “The Genetic Link of Eating Disorders,” The Active Times. At https://www.theactivetimes.com/fitness/n/genetic-link-eating-disorders.