It's based on your BMI. Your BMI has to be above 35 with two major comorbitities or 40 without them. Your actual weight has nothing to do with it. Insurance gets to make a lot of those rules, most require a 6 month physician supervised diet before they will pay for it. I work in a surgeon's office that does the Lap-Band and the Gastric Bypass. Hope this helps!!!
In the US. it goes by the National Institutes of Health (NIH) guidelines, which are BMI of 35 with a weight-related comorbidity or a BMI of 40 or higher regardless of comorbidities. Some insurance companies try to stipulate otherwise (for example, some say you have to have a BMI of 50 of greater for the DS), but they can usually be beaten by appeals since their guidelines don't follow the national standard.
Highest known weight: 324
Weight on morning of DS surgery: 308.5
Got down to about 185 before pregnancy;
Benjamin David born March 24, 2012, 7 pounds 11 ounces