According to the American Psychiatric Association (DSM-IV, 2000), bulimia is a pattern of binge eating and purging the sufferer feels unable to control while anorexia is a refusal to maintain a minimally normal body weight associated with refusal to eat. While bulimics eat almost uncontrollably and then purge, anorexics eat little.
Butcher, Mineka and Hooley (2003) report that there is a degree of overlap between anorexia and bulimia in that it is possible for patients to suffer from both conditions at the same time and/or swing from one condition to the other. Further, the conditions are similar in terms of their causes. As noted by Butcher et. al, in both conditions, patients suffer from a fear of being fat and perceive themselves as fatter than they really are.
This fear of being fat is central to both conditions, and both anorexics and bulimics may perceive themselves as being far fatter than they really are, a body image misperception that fuels the condition. Butcher, Mineka and Hooley (2003)report that other possible causes of one or both disorders may have to do with higher levels of the neurotransmitter serotonin, genetic predisposition, and or the pressure of living in a culture that values thinness. Personality variables are also said to play a role: these include factors such as the need to feel in control, a preoccupation with pleasing others, fear of rejection, and low self-esteem.