Tolkien walked a lot and must have done a fair bit of backpacking too. It adds so much to the credibility of the characters and their journey. Real-life backpacking does get sweaty, there are sometimes uncomfortable numbers of midges, trails do get confusing. Time is spent every day setting up camp and taking it down again. At that point I surfaced from the book thinking, 'Oh yeah, heroic fantasy, I forgot.
Nobody needs to eat.
I don't think so. A summer backpack holding one jersey, something to sleep on, something to sleep in, five days' food and something to cook it on makes a load about the size of my own body. Unless we're talking that freeze-dried stuff from tramping shops which I don't think Simon Snowlock was using either. Polar travellers reckon on using about 5000 calories a day, it's a great sport for anyone that loves an all-fat diet. Yeah, right, obviously they were hunting and stuff, and Tad Williams doesn't want to bother telling us about it because that section of the book is long enough without it, but it shows up the difficulty of providing enough detail to make something believable without bogging down in trivia.