According to one analysis, the percent of women who will have anorexia at some point in their lives may be up to 4%, or up to 2% for bulimia and binge eating disorders. Rates of eating disorders appear to be lower in less developed countries. Anorexia and bulimia occur nearly ten times more often in females than males. The typical onset of eating disorders in late childhood to early adulthood. Rates of other eating disorders are not clear. Classification
ICD and DSM diagnoses
These eating disorders are specified as mental disorders in standard medical manuals, including the ICD-10 and the DSM-5. Anorexia nervosa (AN) is the restriction of energy intake relative to requirements, leading to significantly low body weight in the context of age, sex, developmental trajectory, and physical health. It is accompanied by an intense fear of gaining weight or becoming fat, as well as a disturbance in the way one experiences and appraises their body weight or shape. There are two subtypes of AN: the restricting type, and the binge-eating/purging type. The restricting type describes presentations in which weight loss is attained through dieting, fasting, and/or excessive exercise, with an absence of binge/purge behaviors. The binge-eating/purging type describes presentations in which the individual with the condition has engaged in recurrent episodes of binge-eating and purging behavior, such as self-induced vomiting, misuse of laxatives, and diuretics. The severity of AN is determined by BMI, with BMIs below 15 noted as the most extreme cases of the disorder.
Also, the media are oftentimes blamed for the rise in the incidence of eating disorders due to the fact that media images of idealized slim physical shape of people such as models and celebrities motivate or even force people to attempt to achieve slimness themselves. The media are accused of distorting reality, in the sense that people portrayed in the media are either naturally thin and thus unrepresentative of normality or unnaturally thin by forcing their bodies to look like the ideal image by putting excessive pressure on themselves to look a certain way. While past findings have described eating disorders as primarily psychological, environmental, and sociocultural, further studies have uncovered evidence that there is a genetic component. Genetics
Numerous studies show a genetic predisposition toward eating disorders. Twin studies have found a slight instances of genetic variance when considering the different criterion of both anorexia nervosa and bulimia nervosa as endophenotypes contributing to the disorders as a whole. A genetic link has been found on chromosome 1 in multiple family members of an individual with anorexia nervosa. An individual who is a first degree relative of someone who has had or currently has an eating disorder is seven to twelve times more likely to have an eating disorder themselves. Twin studies also show that at least a portion of the vulnerability to develop eating disorders can be inherited, and there is evidence to show that there is a genetic locus that shows susceptibility for developing anorexia nervosa.