However, their regulatory behavior in human gastric tissue and association with postoperative weight loss following metabolic and bariatric surgery (MBS) remain unclear.<h4>Methods</h4>In this prospective case-control study, gastric tissue from 50 patients with obesity undergoing laparoscopic sleeve gastrectomy and 48 non-obese controls was analyzed for FTO and MC4R mRNA expression using quantitative PCR. Here, MC4R is linked to obesity due to melanocortin 4 receptor deficiency.