Get yourself some wool!
This is a shirt for the long and lean, even more so than with other icebreaker products. Bodyfit is tight but it is meant to be a baselayer. I am six foot even and weigh 165 and this shirt in a med is form fitting without being constricting. I often end up getting a size large in shirts cause i got them monkey arms, but this shirt actually bunches up just a lil' because there is actually excess sleeve! If i could change one thing about this shirt i would make it an inch or two longer thru the body however it fits just fine.