CNR1 and obesity due to melanocortin 4 receptor deficiency: The dysregulation of the endocannabinoid system seems to play a crucial role in human obesity [149], which can be demonstrated by significant abdominal fat accumulation [151], as well as the fact that CNR1 gene variants are associated with an increased appetite, BMI, waist circumference, and skin-fold thickness, and even the appearance of metabolic syndrome [152,153].