Swimming is a good weight-loss exercise, but it is not the best or fastest way to slim down. Runners and bicyclists lose more weight than swimmers during their exercises. More importantly, your body's reaction to being under water has a post-exercise impact that makes swimming a less effective weight-loss exercise than exercises that cause you to lose the same amount of calories during the exercise, according to "The Merck Manual of Medical Information."
Running and bicycling fast are the fastest ways to slim down, according to a study of about 150 exercises published by the Harvard Heart Letter in 2004. Running 10 mph and bicycling burn 1,466 calories per hour in 185-lb. people and 1,228 and 990 calories per hour in 155- and 125-lb. people. By comparison, the fastest swimming exercise, swimming while using the butterfly or freestyle strokes, burns 976 calories per hour if you weigh 185 lbs., 818 calories per hour if you're 155 lbs. and 660 calories hourly if you're 125 lbs. Speed is less of a factor in swimming than above-water exercises because your heart rate is slower under water and, thus, isn't an accurate measurement of exercise intensity, according to the textbook "An Invitation to Health." In above-water exercises, you burn more calories if you exercise more intensely, and you're exercising more intensely when you move faster.
Swimming the butterfly stroke is the fastest way to slim down via swimming, based on information provided by the Harvard study and a study of 175 exercises by the state of Wisconsin. The butterfly stroke is tied with the freestyle in the Harvard study, but is first in the Wisconsin study. The breaststroke is third in the Harvard study and tied for second with the freestyle in the Wisconsin study. A 155-lb. person burns 744 calories per hour swimming the breaststroke in the Harvard study and 704 calories hourly in the Wisconsin study. The backstroke is the slowest way to slim down of the four major strokes, according to both studies. A 155-lb. person burns 596 calories per hour backstroking, according to Harvard's study.
Swimming "isn't the best choice" as an exercise for weight loss, according to "The Merck Manual of Medical Information." When you exercise out of water, your body temperature and metabolism increase for up to 18 hours. Consequently, you will burn more calories after you exercise regardless of your activity than you will burn if you hadn't exercised. Exercise under water does not have this effect because water conducts heat away from your body and, thus, your body temperature stays the same and your metabolism goes down to its pre-exercise level when you're finished swimming.
Although swimming isn't the fastest way to slim down, it should be considered as a weight-loss activity because of its other advantages. "Invitation" author Dianne Hales writes that swimming is an excellent exercise for cardiovascular fitness, muscular function and muscular flexibility. "The Merck Manual" reports that swimming "exercises the whole body without stressing the joints and muscles." Well-known exercise expert Dr. Kenneth Cooper rates swimming as one of the five best exercises for your health along with cross-country skiing, running, bicycling and walking.