Chapter 14 Swimming the Pounds Away

“Swimming? Absolutely the best all-around exercise. But if you want to lose weight, you need to run.”

A lot of people still believe this, and a lot of people are wrong. It’s an issue of more than passing interest to anyone who wants to shed a few pounds and prefers to spend most of his or her available exercise time in the pool. Actually, there’s no scientific reason to be discouraged, and there’s every reason to take heart.

Swimming has long suffered from a bad rep—especially compared to running and cycling—when it comes to weight control “Great exercise but no fat burner,” repeat the skeptics, driving people unnecessarily onto the pavement in search of trimmer bodies. And you can understand how an unscientific sampling could seem to prove this. Just look at the number of gaunt runners slipping through the streets on a Saturday morning. Everyday athletes, not even elite champions.

But let’s get scientific for a minute. The real question is, do swimming workouts burn as many calories—and as much fat—as running or biking? Several studies have suggested that they do not. But in each case the deck was stacked experimentally. The flaw common to all the studies was that the swimming, and the running to which it was compared, were not done at the same intensities. The swimming paces were far too slow to provide a reliable comparison.

Then, a 1989 study at the University of California at Davis finally compared the weight-loss effects of running and swimming on two groups, both of whom exercised at identical intensities: 75 percent of maximum capacity for every subject in both sports. And what do you suppose happened? The swimmers not only lost as much weight as the runners, they actually lost slightly more.

And four years later, Howard Wainer, a Princeton, New Jersey, swimmer who also happens to be a statistician calculated that champion swimmers burn about 25 percent more calories per hour than champion runners. Wainer’s study, published in Chance, the journal of the American Statistical Association, suggested that swimming takes more energy because the drag forces of water are so much greater than air resistance on land, and also because swimmers work so many more muscles than runners.

Swimmers, of course, found none of this surprising. People who know the sport realize that elite swimmers are just as lean as elite athletes in any other sport. They simply look bigger than top runners, for example, because they are bigger. Fast swimming requires a powerful upper body, so swimmers’ arm, chest, and back muscles are typically far more developed than those of runners or even cyclists.

So equal work produces equally lean bodies among serious athletes in swimming and other sports. But what about the obvious weight differences between casual swimmers and casual runners? In part, I’m convinced, it’s a matter of simple psychology. Since your body weight in water is only 10 percent of what it is on land, an overweight runner feels every extra pound with every single step, while a chunky swimmer can be supremely comfortable. So, who has more motivation to watch what goes onto the plate?

Researchers have a more scientific explanation for the same eating behavior. Swimmers usually weigh more not because they burn fewer calories than other athletes, but because they consume more, says a study done by Dr. Grant Gwinup at the University of California at Irvine Medical Center. Gwinup’s reasoning: Water at, say, 78 degrees Fahrenheit draws much more heat from the body than air at the same temperature. And swimmers’ bodies react to that by adding protective insulation, which of course requires food to build up. My personal experience convinces me Dr. Gwinup is right. I never feel like eating after a run, while after swimming, I’m always primed to strap on the feedbag.

However, elite athlete or no, several strategies can help you both burn more fat while swimming and depress your post-swim-workout appetite when you’re done. First, stay full-feeling simply by staying well hydrated (see “Hydration: When Swimmers Run Out of Water” on page 220). Drink ample fluids during the workout, which you should be doing anyway. Second, allow yourself some judicious snacking on filling but low-fat foods (such as fruit or fig bars) immediately after your swimming workout. That will tame your stoked-up appetite without piling on pounds.

How—and even when—you swim can affect the amount of fat you end up burning. During intense exercise, your muscles must rely on a very limited supply of stored energy. But swim with or using moderate effort and that all changes. Though it takes longer to burn the same number of calories at a slower pace, a greater percentage of the fuel being used is fat.

And physiologists now believe we can actually train our bodies to burn more fat even at higher intensities. The crossover point is usually somewhere around 60 percent of an all-out effort—fairly low, actually—after which our burners switch over to carbohydrates as we work harder. But with the right training we can keep fat going into the furnace at efforts as high as 70 percent or even 80 percent of maximum.

Do this: Schedule a long swim practice (sixty to ninety minutes or even more) after eight to twelve hours of carbohydrate deprivation. The easiest way is to plan your workouts for the morning, before breakfast. By swimming easily for sixty to ninety minutes you’ll burn more stored fat (Total Immersion intervals can do this as well as non-stop swimming can—they just have to be easy intervals), and the more you repeat this routine, the more you’ll condition your body to use fat rather than stored muscle energy (called glycogen) as fuel.

Need more of a carrot to do that much work on an empty stomach? Here it is: That University of California at Davis study also showed that prolonged, easy aerobic training sessions give you an impressive after-burn, boosting your metabolism so you continue burning extra calories for up to twelve hours after you finish your workout. 

Bottom line: You can lose weight in the pool. Any swimmer having trouble with the pounds ought to blame his fork, not his sport.