GoodJohn wrote an answer about Arc'teryx Atom LT Hooded Insulated Jacket - Men's on January 11, 2013
I'm 6'1 and 220 lbs. I got XL and its perfect for me. It is a fairly relaxed or regular fit in my opinion. If you like it snug the I would try the L.
Recommended wash is 30 degrees celsius or low temp and hang to dry, has never shrunk/shrinked (?) when I've washed it