Inclusion criteria includes adults (18-65 years-old), of both sexes, and candidates to elective major operations such as subtotal gastrectomy, colectomy, and anterior resection of the rectum for malignancies. Exclusion criteria were having diabetes mellitus, chronic kidney failure, chronic liver disease or serum bilirubin greater than 2 mg/dL, body mass index (BMI) above 35Kg/m2, American Anesthesiologists Association (ASA) score above 3, gastro-esophageal reflux, gastroparesis or intestinal obstruction. Patients with any non-compliance with the study protocol, or who had associated operations, or presented severe intraoperative complications (any type of shock, cardiac arrest, coagulations problems), or experienced prolonged operations (lasting more than 6 hours) were also excluded.