I went off of reviews and the sizing guide, and a small was WAY too tight for my 5'6" 150 pound frame. I'm slightly muscular, and the lieutenant bands actually cut off circulation. I reordered a medium, and it's exactly the same size. It looks fine on, just ridiculously tight around my forearms no matter the size. It's definitely a typical bag dress, and it is not loose fitting as indicated by the picture of the model.