The apparent persistence of eating disorder specific cognitions and emotions and comorbid disorders despite normal or high endogenous leptin levels adjusted for sex, Tanner stage and BMI is reminiscent of the widely used but inadequately defined terms “clinically observed leptin non-responsiveness” [41] or “leptin resistance” [17] in the context of obesity. Here, LEP is linked to obesity due to melanocortin 4 receptor deficiency.