I agree with MayMay21. I just had surgery on Monday 12/20.... but my first day and a half home I was so weak and nauseated that trying to drink protein shakes made me vomit almost immediately . So the last 2 mornings I've started slowly with one water then, 15 minutes later I switch to a mix of half ounce water & a half ounce protein shake for most of the rest of the day. I've been able to keep it down and now I feel much better...no more weakness, dizziness or nausea. Good luck!