I traveled for a year with a 30L backpack that weighed 16 lbs total.
I took 4 pair of socks and underwear 4 shirts and 2 pair of pants.
Everything I took with me is listed here:
http://strattondelany.tumblr.com/pos...taking-on-this
I was able to take my 30L pack as carry on, never having to wait for checked luggage. You don't need all the things you think you need.
I didn't buy anything along the way except for toothpaste when I needed it or contact lens solution. I wore the same four shirt for a year straight.