Outline and Evaluate Biological Explanations of an eating disorder (8 & 16 marks)

One biological explanation of Bulimia is Evolutionary explanations. Abed (998) said that bulimia is a direct consequence of trying to attract a mate. Weight loss comes from trying to get a good body shape and high hips-to-waist ratio to attract a mate. This comes from men evolving to avoid even the slightest thickening of the waist in order not to have another man’s child. Our drive to be thin has adapted from a need for younger women to differentiate themselves from older women, but as in today’s western societies older women fit the desired body shape there is pressure on younger women to go ‘one better’ which leads to eating disorders.

Soundy et al (1995) conducted a study to support this by studying bulimia in females in the US for 10 years. He found that bulimia was 33 times more likely in females than males. This supports evolutionary explanations as the females are trying to be thin to attract males but males who do not need to attract other males do not feel the need to try so hard to be thin.

It can be argued that evolutionary explanations are based on little or no evidence and that they tend to ignore any facts that do not fit the proposed theory. In this case bulimia does not take into account that thin is not seen as attractive in all cultures. The Social learning theory which says that we learn through observation could explain this as in our culture we see other people, especially in the media, trying to be very thin and so observe and copy this behaviour whereas in other cultures they do not see this and therefore the Social Learning theory would say that is why eating disorders are not as apparent as they are in western cultures. This would argue against evolutionary explanations as it is a more behavioural based explanation of bulimia.

Another criticism of this evolutionary psychology is that it is deterministic and says our genes are the reason for the way we behave and fails to take into account individual differences and free will along with anything else that could explain why someone has bulimia such as the media.

Another biological explanation of Bulimia is neural explanations. One of the neurotransmitters involved in this is serotonin. An imbalance in serotonin has been linked to bulimia as it has a big role in controlling anxiety levels as well as perception of hunger and appetite. Low levels of serotonin result in depression while high levels result in anxiety. Binge eating may raise serotonin levels to decrease depression but can then cause anxiety causing purging in bulimics.

Smith et al (1999) carried out a study into serotonin as a factor for bulimia by comparing giving some participants with bulimia snacks and drinks containing an amino acid that occurs naturally in food and is used by the body to produce serotonin and some snacks and drinks without this. He found that after being starved of this amino acid for 17 hours greater dips in mood and concern for body image were shown. This supports serotonin as a factor for Bulimia as it shows that lowering the levels of serotonin in the brain does in fact trigger characteristics of bulimia.

If Bulimia is actually a product of abnormal serotonin levels it should therefore be treatable by drugs that target serotonin levels specifically. Walsh et al (2000) conducted a supporting study into this by giving 22 patients with Bulimia either a course of fluoxetine (a drug which targets serotonin levels) or a placebo. He found significant improvements in the patients who had been given fluoxetine, especially in terms of decreased binging and purging. This supports neural explanations of bulimia as if it can be treated by a drug targeted at neurotransmitters then it must be down to this that it occurs in the first place.

There is an age bias in a lot of research into bulimia as it mostly focuses on adolescent girls and young women. However Mangweth-Matzek (2006) found that 4% of her 475 people sample of 60-70 year old women also fit the diagnosis criteria for bulimia. This shows that bulimia should not just be looked into for younger women but also older women when they show weight loss and vomiting symptoms.