Some psychobiological aspects of adolescent growth and their relevance for the fat/thin syndrome (anorexia nervosa).

Adolescent attitudes to body shape and weight are radically different between the sexes. Females, within a very short time of crossing their pubertal "threshold", usually wish to minimise their shape and often construe themselves as "fat" when it is evident that they are not in fact obese. The majority attempt to "diet" and often succeed, at least intermittently, in substantially reducing the amount of carbohydrate in their daily food intake. This "fatness" of females has important biological and social functions, being closely related to sexual reproductive tasks and being also an important aspect of their appearance and "attractiveness". In contrast, males rarely have such concern about their shape unless they are massively obese or have major gender identity problems. Fatness in both sexes is also associated with growth rate, being greater in those who reach puberty early. Such "puppy fat" together with the commonplace adolescent female's attitude to her own shape are, in the face of adolescent psychosocial stress, contributory factors to the development of anorexia nervosa (the thin/fat syndrome) in many such women who would otherwise tend to obesity. The relevance of body weight and fatness for the pubertal "threshold" process and the mobilisation of this as a central mechanism within the disorder is discussed.