In humans, a number of studies have demonstrated that ghrelin levels are elevated in patients suffering from anorexia nervosa [119,120,121,122,123] and cachexia [124,125] and that the ability of ghrelin to acutely stimulate subjective hunger is blunted in anorexia nervosa patients [126], which raised the possibility that ghrelin action is limited in these disorders. This evidence concerns the gene GHRL and anorexia nervosa.