Losing weight before surgery
The surefire way to lose weight quickly so as to qualify for the surgery is to go on an Optifast diet. Have your doctor/clinic prescribe it for you. Personally, I have found Optifast more successful than my RNY for dramatic weight reduction. On April 26,2011 I started an Optifast diet weighing in at 392 lbs. On September 27, 2011, just 23 weeks later, I weighed in at 261 lbs ...... a 131 lb weight loss during that period.
On October 27, 2016 my weight had crept back up to 319 lbs so I went back on another Optifast regime which is just wrapping up now, 32 weeks later. My current weight is 186 lbs for a weight loss this time of 133 lbs so there is no doubt that in my mind that Optifast works for weight loss, it's just not a recipe for ongoing weight management ........ that continues to a matter of self-discipline.
In all likelihood your doctor/clinic will put you on a three week liver reducing pre-surgical Optifast diet no matter what your weight is before the operation, that seems to done everywhere here in Canada. In your shoes, I'd just go on an extended version until I got my weight down low enough to satisfy their surgical requirements.
For the record, I went in for my RNY on February 6, 2012 weighing 304 lbs and my lowest post bariatric weight was 242 lbs but as with the Optifast diet, surgery is useful for weight reduction but is not the final answer for long term management. That requires self discipline and ongoing dietary controls that can easily be subverted if you are not prepared to commit to the necessary lifestyle changes. I regained all my post surgical weight loss and an extra fifteen pounds on top of that so keep in mind that the surgery itself will only give you about a six month to one year head start to permanent weight reduction ....... the rest will still be up to you and the hungry demons inside your head.