Swimming has gotten a bad rap as an exercise for weight loss. Unlike running, which curbs your appetite, swimming seems to increase it.
Studies comparing swimming with walking and cycling weight-loss programs found that swimmers gained five pounds on average, while the other two groups lost between 17 and 19 pounds. The culprit seems to be the increased appetite that follows working out in water, since swimming lowers your body temp and the body crave calories to help heat it back up. Plus the swimmers weight gain could be attributed to an increase in lean muscle mass, which would have changed their body composition without weight loss.
See how I think you can make swimming part of your weight-loss plan, when you read more.
If you are swimming for weight loss, I don't believe you should give up on the pool entirely — swimming is a great full-body exercise. I do think you should add some cardio training on land. I am a firm believer in cross-training, so adding strength training and walking or running will help burn calories as well as build bone density, which is another benefit of weight-bearing exercises that you miss out on when swimming. When you do finish a swim workout, take a sauna, a steam, hot tub, or a hot shower to help heat your body. Also try sipping on some hot herbal tea as a post-workout drink.