Preoperative Optimization With Tirzepatide, Ketogenic Diet, or Standard Care Before One Anastomosis Gastric Bypass Surgery

Inclusion Criteria: * Age 18 to 65 years at enrollment * Body Mass Index (BMI) between 40 and 55 kg/m² at screening visit * Appropriate candidates for bariatric surgery according to current international guidelines (IFSO 2022) with documented failure of conservative weight loss attempts * Presence of at least one obesity-related comorbidity: Type 2 Diabetes Mellitus (HbA1c at least 6.5%, fasting plasma glucose at least 126 mg/dL, 2-hour OGTT glucose at least 200 mg/dL, or use of antidiabetic medications); Hypertension (systolic BP at least 140 mmHg or diastolic BP at least 90 mmHg, or use of antihypertensive medications); Dyslipidemia (total cholesterol at least 200 mg/dL, LDL-C at least 130 mg/dL, HDL-C less than 40 mg/dL for men or less than 50 mg/dL for women, triglycerides at least 150 mg/dL, or use of lipid-lowering medications); Obstructive Sleep Apnea Syndrome (AHI at least 15 events/hour or AHI 5-14 with symptoms requiring treatment) * Ability to understand study procedures and provide written informed consent * Demonstrated ability and willingness to adhere to study protocol requirements including preoperative interventions and postoperative follow-up visits * No use of GLP-1 receptor agonists or dual GIP/GLP-1 receptor agonists within 12 months prior to enrollment Exclusion Criteria: * History of any prior bariatric procedure or major upper gastrointestinal surgery that could confound outcomes or increase surgical risk * Severe uncontrolled psychiatric disorders …