The minimum weight or body mass index (BMI) for weight loss surgery may vary depending on specific medical guidelines and the type of bariatric surgery chosen. In general, the most common criteria are. Requirements Body Mass Index (BMI): A BMI of 40 or higher (extreme obesity). A BMI between 35 and 39.9 (grade 2 obesity) in combination with serious health problems related to being overweight, such as type 2 diabetes, high blood pressure or severe sleep apnea. Other Considerations: Patients who have previously unsuccessfully tried to lose weight using conventional weight loss methods. Patients who are psychologically prepared for the surgical procedure and associated lifestyle changes. The absence of any medical conditions that could make the surgery dangerous. It is important to emphasize that the decision-making process for stomach reduction is individual and complex. The final decision should always be made with a bariatric surgeon and after a thorough medical evaluation. Some countries or specific medical institutions may also have their guidelines and criteria. It is therefore crucial to obtain detailed information and advice.