Is it true that swimming is a bad activity choice if you want to lose weight?

— Joey Diaz, La Jolla, California

Once, though doubtfully for all, weight loss is simply and solely a result of calories expended being greater than calories consumed. If swimming is your activity of choice, as long as the caloric demands of your swimming exercise put you in a calorie deficit for the day, you'll lose weight. In fact, swimming is an excellent way to lose weight, due to the relative ease with which you can burn calories. Depending on your swimming abilities and speed, you'll churn through between 450-1000 kcal/hr, which is about as good as it gets in the aerobic world. An added incentive for weight loss via swimming is the joint friendly nature of the sport-- the no-impact factor keeps the risk of injury low.

This rumor about swimming being a less efficient way to lose weight probably got started because there have been reports that elite swimmers, especially females, tend to have higher percentages of body fat than their land-based counterparts. For example, elite female runners may have body fat percentages as low as ten percent, while elite swimmers are in the range under 20 percent. Since both of these figures fall considerably below the 25 percent body fat of a typical female, the distinction is fairly meaningless to most of us. Additionally, there is a bonus to the higher percentage of body fat, especially relative to males, as it improves swimming economy by improving buoyancy.

If weight loss through aquatics is your plan, get good instruction on the fundamentals of all four swimming stokes, freestyle, backstroke, breaststroke and butterfly. Mix up the strokes during your swimming to keep your body guessing what's next. The strokes that are hardest to do (like that killer butterfly) are the ones that are really going to burn calories.