So how does this help more than just a restricted calorie diet? Wont the weight loss regardless shrink your liver? Or is it something about liquids only?

Liquid diet is preferred by surgeons because they want to clear your guts/intestines. There are less chance of complication such as "ileus" or bowel obstruction from anesthesia. When under anesthesia the bowel/guts go to sleep and chances are --if there's solid food there, it can cause bowel obstruction. Also if you throw up food while having surgery, food can get in your lungs w/c can cause complication. So liquids are preferred, hope this helps.