Note that this is made of some kind of rubber material, like a tight vinyl almost. I ordered a large because I have a small waist but really wide hips, and I am glad I did, definitely suggest sizing up since this material is really tight yet comes with sufficient hook rows for you to adjust down as needed. Be prepared to struggle with this to get it on! It took me lying down on my bed to really get this guy on, but by the second wear I had gotten a good idea of how to properly place it on and I was happy with it. I don't know much about getting a good workout with it on tho, I am 5'2" tall and have short torso, so it was hard for me to bend/move easily, however just wearing it and walking around the house was a workout alone and I was really sweaty in my waist area when I took it off. I ended up buying a purple one that is advertised as being 9" long/tall and was way shorter for my workouts and that worked out great for me, so I am guessing this one must be around 12" long/tall. They sell these alot now at a few boutique stores, so if you can, I would suggest you go try them on and then come back here to make the purchase (much cheaper online).