Concepts of eating disorders have altered so that anorexia nervosa is now recognized as an important but uncommon syndrome within a spectrum of disordered eating. Behaviours used by dieters constitute the mild end of the eating disorder spectrum. Dieting in young women is for the most part a transient and benign activity without longer-term consequences. However, a group of dieters do progress to develop the symptoms and behaviour of eating disorders, so that dieting has been associated with an eight-fold rise in the risk of later eating disorder. Dieting or factors closely associated may account for most eating disorders in young women. Many antecedents of eating disorder appear to operate through increasing the risk of dieting rather than determining eating disorders specifically. Only the development of further neurotic and depressive symptoms characterizes dieters progressing to eating disorders. As the evidence implicating dieting in the origin of eating disorders becomes stronger so strategies for primary prevention become clearer.