Gastric sleeve surgery

I am scheduled for the gastric sleeve surgery in less then two weeks I am on the second day of the liquid fast I would like to say it is easy but, at night for some reason I am starving. I have had to pray often. I have not been afraid until now. I am worried that it will not work. I have watched people who had it start to gain weight back. I am trying so hard but, my head is starving not my body.