It will give your body a nice shape, and will make you lose weight
I, too, have been doing swimming twice a week, and have recently been maintaining my weight (currently trying to lose 1-2 kgs), and it shaped up my body nicely even though it’s only twice a week
Great full body low impact, full body resistance training. If you don’t account for extra calories that you burn you could find your self loosing muscle as well; hence why novice to experienced swimmers will greatly increase their calorie intake. If done correctly you find your self burning away bad fats while at the same time toning your body.