Considering that CB1 receptors are distributed in the brain, adipose tissue, pancreas, gastrointestinal tract, skeletal muscle, heart and reproductive system, while CB2 receptors are mainly expressed in the immune system [9–11], it’s interesting to explore how CB1 and CB2 receptors involved in endocannabinoids to induce obesity and fatty liver. The gene discussed is CNR1; the disease is obesity due to melanocortin 4 receptor deficiency.