I wrote a review yesterday but it has not posted yet.  I wanted to give an update so people considering this purchase can benefit.

I am 5'4" 165 lbs and normally have a 33-35 in waist.  I ordered the medium.  After only one day, I realize I will have to transition quickly to a small to meet my goals.  It's all good...on day one, I was only able to fasten the medium cincher on the first set of hooks.  Before I went to bed, I moved the fasteners to the second set.  While this is not entirely comfortable, it is obviously quite tolerable and I think I will "graduate" to a small (already on order) very soon.

If I have good success, I may have some mediums that are barely used to pass on.