Anorexia nervosa (AN) is a disease mainly of the female sex (90-95% of cases). Almost exclusive, in the past, of the middle-upper classes, in more recent years it has spread to all social strata. The origin and course of eating disorders (ED) are determined, due to the multifactorial etiology, by a plurality of variables, none of which, alone, is capable of triggering the disease or influencing its course and outcome. Therefore, to understand them in full, it is necessary to take due consideration of biological, psychological and evolutionary factors. The role of some conditions present since birth or childhood, such as genetic vulnerability, family environment and traumatic experiences is not yet well understood in AN pathogenesis. In many cases, some individual characteristics such as perfectionism, low self-esteem, poor ability to regulate emotions, difficulty in conscious management of the body and body image in adolescence precede the onset of ED. Certainly, socio-cultural factors also favor the development of these disorders, in particular the association of thinness with beauty and personal success.