Recently, these knockout models have allowed the identification of several singular molecular components for the development of obesity [5], e.g. of leptin [6], insulin-(receptor) [7], interleukin-6 [8], GIP-(receptor) [9], pro-opiomelanocortin (POMC) and derivatives [10]. This evidence concerns the gene POMC and obesity due to melanocortin 4 receptor deficiency.