I'm on a pre-op VLC diet but what about after?

Right now I'm eating between 800-1000 cals per day as instructed by my doctor. It's not easy and I feel rubbish but it will be worth it! I've been doing it for two weeks and I'm in surgery on Thurs but... My question is what do I do after? They haven't given me any advice. I weigh 225lbs, female and 5ft 5. I know now how strict I can be with controlling my eating so I want to lose weight. I'm worried that after eating such a low calorie diet I will pile it back on if I eat too high! Should I start with not restricting until I am healed or could I go straight to about 1600/700?

Any help would be great