I have not yet had the surgery, so I am not talking from experience here... However, I went to 2 different seminars with 2 separate practices and both stated that it does not matter if you only eat minimal calories, that your body will fight against you and prevent you from losing weight after a month or so. It was described as a room with a window open and the air on - the air (your body) will continue to try and regulate your body (the room) to maintain your weight. Funny though, your body lets you gain, but not lose. I was told that this diet does a type of "reset" for about 1 1/2 years "golden period" and allows you to break past that set point. I was also told that it does effect your hormones and the research I have done on this seems to support it.... otherwise, why would so many people be cured from diabetes, pcos, metabolic syndrome, which are hormonal disorders.
Also, just as a FYI my nutritionist told me that your body would not allow you to lose weight for long and not for long term if you were just on a restrictive calorie diet (which it sounds like you are on in a normal basis) without surgery.
So anyway, I think that there is more to it than just restrictive. I would not be having this surgery if it was only restrictive.
Hope what I have been told is right....
MLeena