How much weight did you lose in your pre-op diet? I start mine tomorrow. Any helpful tips, suggestions??

The amount you lose depends on several things, starting with you and your body.

Surgeons often vary and differ in the pre-op diets as well as post op diets. For me, during my preop I was allowed 3-4 protein shakes a day, broth, sugar free jello, sugar free popsicles, G2, and Powerade zero... and of course water with and without crystal light.
I personally was on my pre-op diet for 21 days. And during that time I lost 16.5 pounds.

I was on a low carb pre-op diet with clear liquids on Day 14. I lost 14lbs overall. The first few days are the hardest but it definitely became easier. Good luck!