I bought two of these, one in the panty style and one with the shorts length to combat thigh chafing. Im about 160lbs, 54 and between an 8 and 10 with an undefined waist, no hips or butt, and very busty (which is why I love that these allow you to use your own bra). I bought the XXL US 8-10 and its a perfect fit even on the tightest hook and eye. It smooths my Mommy tummy and nips in my non-existent waistline (think upside down triangle shape). It shows under very clingy and thin fabrics, but is invisible under everything else. Sadly, anything thin and sleek that doesnt show under a clingy dress also doesnt have the holding power these do. I felt like a 1950s movie star strapping into a girdle to wear a classic glam ball gown, but its so worth it