They never told me about any Proteins as well, my first 15 days I was only with sugar free drinks and broths. I went to a nutricionist and she gave me this milk called Glucerna which reduced my white tongue, it was do to dehydration. I was not drinking Water at all and left too much time in between my ounces of liquids. You should be taking little sips of water every 10/15 mins. Therefore you are always hydrated. I'll attached the diet my nutritionist gave me so I could rehydrate again.
HOPE THIS HELPS its in spanish if you have any questions feel free to ask!