What I really like about them is that I can wear them all day and they don't hurt my feet. I have also noticed that my back doesn't hurt as much either. As far as the actual "shape up" part of them, I'm not so sure. My husband says that I look smaller from the rear if you know what I'm saying - but he could be lying (I think he might be). I'm not working out in them, I just wear them as you would any tennis shoe. I have walked around in them quite a bit and still no foot pain and I have stood in them working on cakes and no back pain!! As far as I'm concerned by butt can stay big as long as my feet, legs and back don't hurt!
This is a picture that I borrowed off the website to show you which pair I got:
You can go online and read all about the Shape Ups, the different styles, what makes them work, how they are built and how much they cost - here.
If you get a pair or have a pair - leave a comment and let me know what you think of them!