Incidence and Prevalence

Estimates of the incidence vary greatly as many cases are clinically undiagnosed. Surveys of young women have found a prevalence of 1 to 2%. About 90% are female. It is more common in upper than lower social classes and in certain occupations, for example acting, dancing, modelling and food related occupations. It is also more common in young people with chronic illness and physical disability. The condition usually begins in adolescence and 85% have an onset between the ages of 13 and 20 although onset in childhood is becoming increasingly common.

Family, biological, social and cultural factors may have a role in the development and maintenance of eating disorders. The following factors are thought to be relevant.

Eating disorders are ten times more common in first degree relatives of affected people than the general population. It is thought that a region on chromosome 1 is linked with AN.

Depression and Generalised Anxiety Disorder are more common in the families of people with eating disorders. The risk of developing an eating disorder is greater in those with obsessive compulsive personality traits such as perfectionism and rigidity in childhood.

Prematurity is associated with a six fold increase in risk of later development of AN.

The prevalence of BN is about 2 to 4% in women between the ages of 16 and 40 years. It is uncommon in men (female to male ratio of 50 to 1) and has only been identified in developed countries. There has been a dramatic increase in detection and diagnosis in recent years.

Amended June 2008