Originally Posted By EMT Dave
I have limited experience but I understand the real reason for using them is to keep the bag clean/er. Seems like they would most be welcome on a long thru hike like the AT.
Perhaps a very light set of long sleeve/ long legged underwear might take its place while serving another function.
But...a big but, is what happens when the weather is hot and you want to be naked?
And what about the twisting about your body question?


Many of us have found it is more enjoyable to have less weight on your back than to have every luxury on the trail. The only experienced backpacker that I've ever come across who claim to use liners are ones selling a used sleeping bag.

In terms of temperature management in a sleeping bag.... check out quilts!