As noted in Chapter 4,10,1, anorexia nervosa generally starts in mid-adolescence with a period of voluntary dietary restriction which proceeds to get out of control. As a result body weight falls and a state of starvation develops. Shape and weight concerns may predate the onset of the dieting or develop as weight is lost.
Bulimia nervosa starts in a similar way although the age of onset is typically some years later, and shape and weight concerns usually antedate the dieting. The dietary restriction resembles that seen in anorexia nervosa and it leads to weight loss sufficient to result in anorexia nervosa in about a quarter of cases. (As a result of referral bias, this proportion is higher in cases seen in specialist centres.) In the remaining cases there is also weight loss but it is less extreme. After a variable length of time (generally within 3years) dietary control breaks down with the patient's dieting becoming punctuated by episodes of overeating. At first, the episodes of overeating may be modest in size and intermittent, but gradually they become larger and more frequent. As a result, the lost weight is regained and body weight returns to near its original level. By this point the disorder tends to be self-perpetuating. At some stage in this sequence of events, self-induced vomiting and laxative misuse may be adopted to compensate for the overeating. In practice, however, both forms of behaviour have the opposite effect since belief in their effectiveness encourages a relaxation of control over eating. In those who vomit this phenomenon is exaggerated by the discovery that the process is easier after eating large amounts of food.
Was this article helpful?