Outline and evaluate explanations of eating disorders based on the biological model of psychological abnormality 
Explanations tend to fall into four categories:
Evolutionary explanations of behaviour are based on Darwin’s theories of natural and sexual selection. These theories have been applied to eating disorders. It is suggested that the ability to control ones appetite and ignore hunger when food supplies were not constant was a successful adaptation. A second idea is that anorexia is a strategy to suppress reproductive function at a time of stress. When normal weight is restored, fertility is restored. This ensures that reproduction takes place when offspring has the best chance of survival. It is difficult to test evolutionary explanations but they imply that eating disorders have a genetic component.
Research into genetics as an explanation of eating disorders is based on establishing whether these disorders ‘run in families’. Investigations were carried out on twins, both identical (MZ) and non-identical (DZ). In identical twins there was a high concordance rate in anorexia with both of the twins getting the disorder. They were not as high with non-identical twins and in bulimia there was 0% concordance. This indicated that there was a genetic factor involved, but also others such as the environment; otherwise the concordance would have been 100%. The results from the investigations suggest inherited vulnerability to the disorder if certain environmental conditions are met.
Research into neuroanatomy as an explanation of eating disorders has focused on the region of the brain known as the hypothalamus. Animals have been known to stop eating and starve themselves when the hypothalamus is damaged. Keesey and Corbett stated that the lateral hypothalamus and ventromedial hypothalamus work together to provide a ‘weight thermostat’. The LH produces hunger and the...
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