Their results showed that the weight gain was similar in both the CB2 receptor knockout and wild-type mice groups, while in the double knockout mice, weight gain was significantly lower; these findings indicate that lacking both CB1 and CB2 receptors protects mice from diet-induced obesity, while the absence of the CB2 receptor only does not protect in this aspect when compared to wild-type mice. This evidence concerns the gene CNR1 and obesity due to melanocortin 4 receptor deficiency.