Gastric sleeve surgery does not interfere with the digestive system in general. It only interferes with the stomach and 80% of it is cut and the stomach is reduced. Especially in the first 2 years following the surgery, there is a very serious weight loss. If patients return to their old eating habits after the 2nd year in the postoperative period, they may gain weight again, although not as much as before the surgery. Stomach has a flexible structure, therefore, when returning to a carbohydrate-heavy diet as before, weight gain can be experienced again.