Starvation-induced alterations of neuropeptide activity probably contribute to neuroendocrine dysfunctions in anorexia nervosa. For example, CRH alterations contribute to hypercortisolemia and NPY alterations may contribute to amenorrhea. Alterations of these peptides as well as opioids, vasopressin, and oxytocin activity could contribute to other characteristic psychophysiological disturbances, such as reduced feeding, in acutely ill anorexics. Such neuropeptide disturbances could contribute to the vicious cycle that has been hypothesized to occur in anorexia nervosa. That is, the consequences of malnutrition perpetuate pathological behavior.