It all depends on how much excess weight you want to lose and how many calories you consume each day. I can also assure you that swimming will not help you get your abs, legs or arms. It will tighten your skin and muscles, but you won't achieve the same results as bodybuilders. If you want to have a beautiful abs, then you may want to consider six pack liposuction, because this method doesn't require any difficult workouts from you either. I've seen a lot of pictures with the caption "after" and it's a really impressive result.