I am wearing a size Medium in this faja a few questions to answer, yes I can eat, breath, and move around without feeling super restricted IT IS NOT A CORSET. There is a zipper from the front the the back to use the bathroom. Go with your original shirt size is what I did. I do not rise up the leg do to the silicone around the shorts part. LTKBeauty LTKFindsUnder50 LTKStyleTip