Some people may feel that they are fat, no matter how thin they actually are. Or they may feel guilty when they eat too much food. The guilt and shame from eating makes the person vomit up all their food. These people have bulimia nervosa, or bulimia, an eating disorder. The disorder has nothing to do with the digestive system, but rather with the mind. And though people with bulimia may share the same guilt and shame about food, and the same patterns of bingeing and purging, bulimia has many causes. Doctors have not identified any one cause of bulimia, but do know of several factors that may contribute to developing bulimia. Bulimia may be caused by a genetic component. Certain genes may predispose a person to developing bulimia. Bulimia appears to run in families?people with relatives suffering from bulimia have a higher frequency of developing bulimia. This may, however, have more to do with family influences and role models than genetics. Brain chemistry may also cause bulimia. Research indicates that people with bulimia tend to have different levels of a chemical in the brain called serotonin. Altered levels of serotonin may also contribute to clinical depression. Social pressures may contribute to bulimia?s development. People who want to please others may feel compelled to keep thin and fit. Women in particular receive daily messages to be thin. This drive may turn into an eating disorder. Emotional stress from family problems or being a perfectionist may also contribute to a person developing bulimia. A person with bulimia will first binge, meaning that he or she will eat more than 1,000 calories in one sitting. Sometimes, to a person with an eating disorder like a bulimia, eating a cookie might constitute a binge. The binge then triggers intense feelings of self-disgust and the person will induce vomiting, exercise excessively, or abuse laxatives to remove the perceived extra weight. Bulimia is caused by numerous, subtle factors, and all people suffering from bulimia need treatment from a psychiatrist and therapy to break the binge-and-purge cycle. Bulimia is completely treatable.