You may be hungry because of a nutritional deficiency. If you can only eat 1000 calories a day you may not be getting enough of something. Surgery is traumatic to your body and that coupled with the very quick weight loss could account for the stall. Just keep keeping on and eventually you should start to loose again. These are all just guesses based on what I have seen in myself and may or not be helpful to you. Take what you like and leave the rest.