Body Mass Index (BMI) is a part of determining your eligibility for surgery. The National Institutes of Health developed this BMI tool to determine if you are at a healthy weight for your height.
In general, to be eligible for weight loss surgery you must meet one of the following criteria:
1) BMI of 35-39.9 with a medical condition related to weight (diabetes, high blood pressure, sleep apnea, etc)
2) BMI of 40 or greater