I have no idea why I have not purchased this earlier. I'm going to be purchasing more. It's the perfect fabric for exercising or just lounging or layering; it's an excellent length, not too long, but flattering to the backside. Wow, it's my new fave!
Fits like a glove, snug but not tight. VERY soft, yet stretchy. Wore it as a base layer to work outside on a raw day, then into the day with an open fleece jacket. Cozy yet more glamorous than your standard "long underwear".
I am 5'3", 128 lbs. and bought the medium.