In the last decade, this correlation has added to the existing knowledge about obesity, including eating behavior influences, such as the activation of the anorexigenic α-melanocyte stimulating hormone, as well as orexigenic neuropeptide Y (NPY) and Agouti-related peptide inhibition, centered by tryptophan (TRP) metabolism [8,9,10]. This evidence concerns the gene NPY and obesity due to melanocortin 4 receptor deficiency.