I'm 5'9, 145 lbs, and wear a size 6 or 8 in pants.  I ordered these in size 8 regular.  These may just rank up there as the most unflattering pants I've ever tried on.  The lines of the pants make my hips and thighs look huge, when they typically don't.  The inseam was so short that I could have waded through a flood without any risk of wet pants.  The pants were very thin with a windbreaker feel and a loud sound when the material moved.  Yikes.  Sent back immediately.  Definitely not for me.