I panicked when I didn’t lose weight the first week too. I had a hard time with any fluids the first few days and wasn’t really able to drink much of the protein until the 5th day. You can sip on it. Do try to get it down in 15 min. In the beginning the water was more important and with so so little hydration I mostly survived on rehydration, zero Gatorade. The 5th day post op I was able to get more of the protein in. The isoprene clear protein mix was a box help with that. Not nearly as thick and rich as the premier type shakes.