Has anyone used any sort of waist trainer or postpartum shapewear to help their tummies go back to…

Has anyone used any sort of waist trainer or postpartum shapewear to help their tummies go back to "normal" or "flat"? I know that our waists may never go back to the same shape (pre pregnancy) but Im seeing these ads all over the place for shapewear. Have you tried it? If so, did it work? What brand do you recommend ?