I'd research other surgeons, just to get a feel for the different approachs....then make your decision.
There is emerging evidence that prolonged super low calorie diets before and after surgery could reset your metabolism to unrealistically low levels that set you up for weight gain later. (not saying this always happens, not saying this is gosple....bariatrics are an emerging science....just sharing that there are a lot of different ideas at play)
My group did a very carb restricted diet for two weeks before surgery. We were allowed to drink 5 shakes a day plus one food item from a list.....but this was just to shrink the liver for an easier procedure.
My group wanted 10% weight loss, but expected it to take months. We were required to work with a nutritionist, attend fitness classes, healthy cooking classes, support groups. Our whole process took 4-6 months...just to lay the nutrition groundwork and weight loss work before the surgery.
After surgery, we were pushed to eat 1200 calories a day as soon as we could tolerate it...in hopes that this would give us a robust metabolic reset. (to be clear, we went through the gradual restoration of diet after surgery for safety....liquid, puree, soft, etc....but our caloric goals were advanced as tolerated)
I lost weight slower than most people....but I made goal, and I'm doing really well maintaining. My preferences and nutrition choices are much healthier. I've got good support for the mental side of this process.
I feel like I was better prepared by my group for the work of making the permenant changes necessary and dealing with the lifetime challenges.
Be a little careful of clinics that push unrealistically brutal calorie restriction. Eating 600 calories a day will make you lose a crap-ton of weight and will make your clinic look like they offer "The Magic Cure"....but you don't need to be their walking bulletin board for a year and then be abandoned by them when you regain. You need a comprehensive program that supports your needs for a lifetime and teaches healthy nutrition and fitness and supports the mental challenges of breaking the addiction.