I am on my 4th day of liquid diet pre op (surgery date 10/25) i am allowed Clear liquids along with the Protein shakes. Along with the shakes I have been drinking chicken broth (also beef or veggie broth acceptable) not only does this actually help with hunger but it has replaced my craving for coffee, since i cant drink coffee without cream. I am also allowed sugar free Jello, which helps a little, you can have caffeine and sugar free teas both hot and cold and for me i drink lots of low cal gatorade. I've had the 'hunger headache' pretty steady for all 4 days but i have also lost 6 lbs, so that is keeping me motivated. Good luck with your surgery!
Lisa