My girlfriend bought these and she is 5'1" and 117 lbs (athletic/muscular build), bought a medium based on reviews saying that these pants run large-- and they were way, way too big around the waist.We could literally stick our 13lb cat in there too and still have extra room to eat a salty burger. Can pull them on and off without unbuttoning them, about 6 inches too large around the waist. They have some elastic on the sides to stretch also, which makes them even bigger. They are a little long, See full review