So far, according to available information, our study has dug to somehow provide detailed insight into the mechanisms linking depression and obesity, where it spotted a significant decrease of serum NRG-1 level in obese people compared to non-obese, at the same time its levels correlated negatively with the score of depression in obese both pre- and post-LSG. Here, NRG1 is linked to obesity due to melanocortin 4 receptor deficiency.