Paper

Outline and evaluate biological explanations of one eating disorder

An attempt at explaining anorexia nervosa (AN) has been explained by Guisinger’s (2003) adapted to flee famine hypothesis (AFFH). AFFH fits under the evolutionary approach, but is also a biological explanation. Guisinger proposes that AN is part of behaviours adaptive in the environment of the evolutionary adaptation (EEA). In hunter-gatherer society, there would have been prolonged periods of famine and it would have been necessary to move on regularly when food resources were exhausted. To cope with this, people would have keep active despite lack of energy. Guisinger draws a parallel with anorexics, who tend to have high activity levels and restlessness, despite the typical response to starvation being inactivity and depression. Therefore, she hypothesised, high levels of activity and a denial of hunger, necessary to migrate in times of famine, and are explanation of AN today.

Researchers such as Holland et al. (1984), however, have claimed that genetics are the best biological explanation of AN. Research into genetics’ role tends to come in the form of twin studies. Holland et al.’s is perhaps the most notable. They researched the genetic link by comparing MZ and DZ twins, where one twin of each pair was suffering from AN. They hypothesized that as MZ twins are genetically identical, if AN characterised entirely genetic, it should be a shared trait. Holland et al. found a concordance rate of 55% for MZ twins and of only 7% for DZ twins. The significantly higher concordance rate for MZ twins suggests a genetic involvement in anorexia nervosa, but clearly it is not the only component in place. If it was entirely genetic, the concordance rate would surely have been 100%.

Both biological explanations—evolutionary and genetic—have a lot of support, but they are not without their limitations. The main problem with twin studies such as Holland et al.’s is the small number of...