I'm in Pre op and surgery is 4/2. My first few days were ok but now I seem dehydrated. I'm drinking a gallon of water along with my 2 shakes. I also noticed this morning, I'm losing my hair. Is this normal or should I call the dr?

Call your dr in you are worried - that is the only way to get peace of mind for your specific situation. But trying drinking more water until you get an answer. It certainly won't hurt you!

Are you taking your vitamins?

there is no way you are dehydrated taking in a gallon of Water plus your shakes. It is more probable that the shaky feeling is just your body trying to cope with the sudden decrease in calories. Make sure you are already taking your Multivitamins if you are already seeing hair loss as you are losing a lot of Protein and it will be close to 2 - 3 weeks before you start getting decent amounts back into your system.

Good luck!

Make sure your protein is at least 60g or your hair will fall out!