Oscillatory instability of body weight in alternating anorexia nervosa and bulimia nervosa

The present study was undertaken to clarify the longitudinal course, from adolescence to age of 40, of weight fluctuations in a woman with alternating anorexia nervosa and bulimia nervosa. Although it has long been appreciated that a single person may fluctuate between states of binge eating and obesity on the one hand, and starvation on the other, few data exist regarding the nature and mechanism of this interrelationship. As opposed to the gradual linear increase in weight normally observed in human beings from early adulthood through middle-age, our patient with alternating bulimia nervosa and anorexia nervosa showed chronic weight oscillation of great magnitude. However, her weight oscillations were periodic, as opposed to chaotic, and oscillated around her ideal body weight of 137 pounds. Moreover, the frequency of major weight changes increased with time. It is possible that a fundamental dysregulation of the hypothalamic feeding apparatus, wherein the normal homeostatic system loses its stability so that periodic oscillatory behavior results, unites the syndromes of anorexia and bulimia nervosa in the same individual. Finally, the pathological weight dynamics observed in this case show similarities to the phenomenology and course of bipolar affective disorders