Yes, the pre-operative diet is intense and obviously feels like a starvation diet. The point is to remove all the sugar stores in your liver so that it shrinks and is out of the way for the actual surgery. Really, this can speed-up recovery time since they need fewer incisions. So if you feel hungry on the diet, drink more water or diet drinks rather than being tempted to eat more food. If you need to cheat - eat more protein not more carbs or fats! It will be worth it in the end!