There are several reasons why you might not be able to get a gastric sleeve surgery. First, gastric sleeve surgery is typically only recommended for people who are severely obese, with a body mass index (BMI) of 40 or higher, or a BMI of 35 or higher with significant obesity-related health problems such as type 2 diabetes, high blood pressure, or sleep apnea. If your BMI is lower than these thresholds, you may not be a good candidate for the procedure.