I think a lot of people might do this, though mixing it with rice doesn't sound too appealing.

For a couple of long trips I went to costco and got the sort of "big can" of some sort of protein shake, mixed it up with powdered milk and used that.

Eventually I stopped, just because I found it a bit of a hassle, plus it tied me to resupply boxes (most trail towns didn't offer anything like this). But my normal, at home metabolism is very different from yours. I think one question that might or might not be meaningful for you is how many calories/day you would need or want after a few weeks of hiking. Wow. It can indeed be a lot of food to carry, so getting calorically dense stuff is a bit more important if you're processing that many calories per day.