I've used this jacket under my hardshell while ice climbing and skiing and it works very well. Very insulating for the weight and the cut is quite athletic. So if you have a bit of a beer gut I would go for something more boxy like a Ghost Whisperer or Western Mountaineering Quickflash. Breathability is great and it stuffs down very small. I'm 6'0" 175lbs and a large fits perfect.