This nonrandomized, prospective cohort study investigates fasting ghrelin and resistin levels in patients undergoing either restrictive [sleeve gastrectomy (SG)] or malabsorptive [one anastomosis gastric bypass (OAGB)] procedures for morbid obesity before and after (1 week, 1 month, 3 months, and 1 year) surgery. Here, RETN is linked to morbid obesity.