Like Burnin' says bring Crystal Light, it gives you an alternative to just plain water. I met this guy on the John Muir Trail, he packs about 20lbs for a 2 week trip. He told me the majority of your nutrition is your body fat, plan to lose a pound a day. As an example, his breakfast consists of 3 pieces of jerky, 28 M&M's (1oz) and 3 chocolate covered espresso beans. Everything is measured out in daily meals in ziplocks. His name is "Purple Hat"
http://www.highsierrawildernessfitness.com/