Eating disorders are rare in the population as a whole but much more common in adolescent girls. The true level of eating disorders in the population is unclear and the results of the studies vary depending on the methods they use. Not all cases of eating disorders are picked up by the healthcare system and some people can have eating-disorder symptoms without necessarily fulfilling all the criteria for bulimia or anorexia. A three-year study of 595 adolescents in Finland found that as many as one in five teenaged girls struggled with eating problems at some point. 2.6% had had anorexia, 0.4% bulimia, 7.7% anorexia symptoms, 1.3% bulimia symptoms and 8.5% other eating problems. The researchers did not find any eating problems among the boys in the study.
Isomaa, Rasmus ... [et al] - The prevalence, incidence and development of eating disorders in Finnish adolescents - a two-step, 3-year follow-up study European Eating Disorders Review May-June 2009, 17(3), 199-207