Demystifying the Genetic and Environmental Influences on Disordered Eating

Genetics play an important role in the development of eating disorders and disordered eating behaviours. To date, many (over 30!) twin studies have been done and all but two found significant genetic effects on the development of eating disorders and disordered eating. However, no methodology is without limitations and tentative conclusions become more convincing when the findings are confirmed using different experimental approaches.

Twin studies, while they offer many advantages, are not that good when it comes to detecting shared environmental effects on a particular trait (literally, evens that happen to both twins and affect them in the same way). Fortunately, twin studies are just one of several different ways that researchers can use to study heritability(A quick reminderHeritability measures the amount of the variability in an observable trait/behaviour that can be attributed to genetic variation. This is NOT the same as … Continue reading →

The Genetics of Thin-Ideal Internalization

The Tripartite Model of body image dissatisfaction postulates that three factors (peers, parents, and media) affect body image dissatisfaction and disordered eating through thin-ideal internalization and appearance comparison.

Thin-ideal internalization is the extent to which one accepts or “buys into” socioculturally defined beauty standards of thinness. The idea is that the more someone internalizes these standards, the more likely they are to engage in behaviours to achieve their “ideal”, and the more likely they are to develop an eating disorder.

A growing number of of studies have been done evaluating the validity of this model. Although I’m not well-read on the subject, it does seem like there is a growing number of studies showing an association between thin-ideal internalization and disordered eating practices.

But is the picture complete? Are peers, parents, and media the only or even the main factors that influence the extent of … Continue reading →

Can Puberty Affect the Development of Eating Disorders?

Eating disorders typically begin in adolescence. One common explanation for this is that during adolescence females are increasingly exposed to the media, thin models, and dieting. While this is probably true to some extent, it doesn’t explain why the rates of eating disorders are quite low despite the high levels of exposure to thin models in the media. Out of 100 girls, only a handful develop eating disorders, yet all of them are exposed to the same magazines and TV shows.

This means there must be some other factors that differ between this group of girls. One hypothesis is that hormonal changes during puberty may modulate the genetic risk factors for eating disorders. These changes may “turn on” genes that predispose individuals to eating disorders. Previous research has shown that genetic factors modulate disordered eating (eating disorders have a high heritability), but how? What are the mechanisms of this … Continue reading →