After Roux-en-Y gastric bypass, there is a downregulation of leptin and resistin gene expression, allowing for the normalization of insulin resistance in obesity. Roux-en-Y gastric bypass specifically, a significant downregulation of leptin and resistin gene proportional to greater excess body weight loss while there was no change in the adjustable gastric band. The gene discussed is LEP; the disease is obesity due to melanocortin 4 receptor deficiency.