About 0.4% of young females are affected in a given year and it is estimated to occur three to ten times less commonly in males. Rates in most of the developing world are unclear. Often it begins during the teen years or young adulthood. Medical students are a high risk group, with an overall estimated prevalence of 10.4% globally.The lifetime rate of atypical anorexia nervosa, a form of ED-NOS in which the person loses a significant amount of weight and is at risk for serious medical complications despite having a higher body-mass index, is much higher, at 5–12%.While anorexia became more commonly diagnosed during the 20th century it is unclear if this was due to an increase in its frequency or simply better diagnosis. Most studies show that since at least 1970 the incidence of AN in adult women is fairly constant, while there is some indication that the incidence may have been increasing for girls aged between 14 and 20. Underrepresentation
Eating disorders are less reported in preindustrial, non-westernized countries than in Western countries. In Africa, not including South Africa, the only data presenting information about eating disorders occurs in case reports and isolated studies, not studies investigating prevalence. Western countries experience slightly higher rates of eating disorders than non-western countries.
Contrary to pleomorphic adenoma, it is non recurrent. See also
Pleomorphic adenoma

References
Additional sources
Kahn, Michael A. Basic Oral and Maxillofacial Pathology. Volume 1. 2001. == External links ==