I think that only you can decide that. I found myself mourning the loss of food as my comforter and friend after surgery. I had to severe the chains that kept me in bondage to food. If you do that before surgery, you're doing good. How do you do it? Identify what it is that holds you captive to food. For me it was wanting to hide behind my wall of fat to keep guys from hitting on me. I am dealing with a lot of being hit on again and I deal with it different now. I don't run to food to hide my feelings. Food doesn't comfort me, it feeds me. I don't live to eat, I eat to live.
It may be difficult to make many changes pre-op because you can still eat a lot. When food is literally taken from you as your source of comfort post-op, you do some serious soul-searching. You work on your mind and your way of thinking because that's what's going to get you through the extremely difficult first several weeks. You do, however, get through it. Does your surgery program have a built-in (for lack of a better word) social worker/psychologist? Mine does. Every chance you get, talk to them about your relationship with food, pre- and post-op! Go to support group. Ask questions. You need to get stuff OUT! A lot of times pre-op, I would not want people to discuss my being fat and I would hide my "problem" of being fat. I would eat in secret or pop a bag of popcorn and down it with a liter of soda and chase that with cookies. My advice is when you have triggers happen (little moments that you don't know why but you just want to eat or graze) talk it out or write about it. Writing or talking about it is amazingly helpful.
Well, good luck. We're always here for you at OH, if you want to keep asking those questions! Enjoy the journey, PoeticOne!