I bought this in an extra large size just in case it had a flattening effect. I wanted something to hold me in, but not squash me (especially in the boob area....I need all the help I can get there).
When I purchased this I was done to my lowest weight in years and almost bought a large because a medium DID FIT in regular clothing. Still, I was worried about the "sqauash element" and in my own eye, I have a large frame; although my mind's eye may not be that accurate.

Anyway The Extra Large fit OK and smoothed my tummy, but my boobs were squashed. For me this was a "no go." I had gone ahead and gotten it because it had good reviews, but for me, at 5'5" and 150 lbs, I was squashed!!! Maybe I am just too heavy overall to wear it. I am not sure what the problem is. But it is not for me.