I'm so glad he's still feeling OK. I suspect that will change in the next week, but to get 3 weeks in is fantastic.
Once the taste buds are gone, you're right...the eating will almost stop, and he'll start to drop the pounds. VHC is good, but there are a lot of other nutri drinks out there that offer very high calories as well. Many find that the taste and/or texture of one brand is intolerable, and have to use somethng else.
I tried VHC and the consistency really didn't work well for me orally. After my taste returned, I found that the aftertaste it left me with was very unpleasant. I used a product called Resource 2.0 ( available at Walmart).
It's vanilla flavored, so you can mix in some other taste easily, and it has a high calorie count as well.
What I'm saying is find something he likes and can tolerate well, and go with it. He'll live almost exclsively on it for at least a few weeks.
He's going to start being really fatigued, so don't worry too much about him sleeping. He needs to...his body is fighting a huge battle
take care
Wayne