Endocrinology of eating disorders

Eating disorders affect about five million Americans every year. There are three different eating disorders: anorexia nervosa, bulimia nervosa, and binge eating disorder. Eating disorders are complex conditions deriving from a complex interplay of long-standing behavioural, emotional, psychological, interpersonal, and social factors. The neuronal circuits that control the ingestion of food are mainly related to catecholaminergic, serotoninergic, and peptidergic systems. In this respect, while serotonin, dopamine and prostaglandin promote the ingestion of food, by contrast, neuropeptide Y, noradrenaline, γ-aminobutyric acid (GABA), and opioid peptides inhibit food ingestion, thus causing the development of eating disorders (1).

Eating disorders typically occur in adolescent girls or young women, although 5–15% of cases of anorexia nervosa and bulimia nervosa and 40% of cases of binge eating disorder occur in boys and men. Approximately 3% of young women are affected with these disorders, and probably twice that number has clinically important variants. Although early disorders mostly develop in adolescence or young adulthood, they can occur after the age of 40 years and are increasingly seen in young children (2). Eating disorders are more prevalent in industrialized societies than in nonindustrialized societies, and occur in all socioeconomic classes and major ethnic groups in the USA. About half of those who have anorexia nervosa or bulimia nervosa fully recover, approximately 30% have a partial recovery, and 20% have no substantial improvement in symptoms (2).

The aim of this chapter is to give an overview of the endocrinology of eating disorders leading to excessive weight gain or excessive weight loss in humans. It is of note that despite the strong association between obesity and eating disorders, the increase in obesity is not followed by an increase in eating disorders (3).