Are you kidding me?!??! My advice to you, FIND ANOTHER DOCTOR if they suggest for a minute that you don't need a pre-op diet. You were lucky....but it is extremely risky not to have a pre-op diet. You have to be the perfect 10% of all patients who don't have either a fatty liver, or one that's enlarged due to high carb intake.
Why? Your liver is going to be in the way of where the doctor needs to operate. There are two MAJOR blood vessels near where the doctor will be poking and prodding around. The descending aorta and inferior vena cava. (see File:Gray531.png - Wikipedia, the free encyclopedia)
Your stomach rests on top of that area, and your liver on top of your stomach. The purpose of a pre-op diet, is to force your liver to burn excess glycogen, so that it shrinks and gives your surgeon extra room to operate. I don't care who the surgeon is, no surgeon is immune from error. One tiny slip up, and he can nick one of those two blood vessels, and you could bleed out by the time you got home.
If anyone considering surgery has their doctor suggest no-pre op diet, PLEASE seek a second opinion. A no pre-op diet is HIGHLY irresponsible of your surgeon. This is your life we're talking about.