I had a baby 8 months ago, and I have a ways to go before I'm back to my pre-pregnancy body. I mostly need help hiding my flabby belly. This bottom is so flattering! It fits quite tightly, to squeeze the belly in, but also comes up high enough over my navel so that it doesn't cause unflattering muffintops. The skirt is also nice and trim, so it's not too long or grandma-ish.
For reference, I'm 5'6" tall and weigh 140 lbs. I'm wearing pants size 6-8, and bought this bottom in size M. I paired it with an empire-waist, halter-style top, which further camouflages my tummy. I've not yet worn it into the water, so I'm not sure how much tighter or looser it becomes when it gets wet. I'm very happy with my purchase!
Runs a little small because it's a tummy slimmer, I bought an XL. Hides everything I want to hide. I'm 5'3 and only mildly chubby so it hits just above my bellybutton. The skirt covers just enough of your upper thighs to make them appear slimmer. Definitely would recommend.