Losing my mind
Are you able to have milk on your pre-op diet plan? I could have skim or 1% milk with my protein shakes and I found that it helped to make me feel less hungry when I did. Even today, I don't get hungry as quickly after a milk based protein shake compared to a water based one.
Good luck with your surgery. I'm wishing you many lost pounds and better health. :)
((Hugs))