Q. The treadmills, stair climbers and bikes at my gym have several programs, including "fat burning," "intervals" and "hills." Naturally, I want to burn fat, but is the fat-burning program on these machines really a better workout than the other programs?
A. "Program labels are mostly gimmickry," says Glenn Gaesser, Ph.D., an exercise physiology professor at the University of Virginia and co-author of The Spark (Simon and Schuster, 2001). "There is no such thing as a fat-burning zone." It is true, though, that during low-intensity exercise, you burn a greater percentage of calories from fat than you do during fast-paced workouts; at higher intensities, carbohydrate supplies most of the energy expended. However, at a higher intensity, you burn more total calories per minute.
"Don't think for a minute that high-intensity exercise isn't good for fat burning," Gaesser says. "The most important exercise factor for losing body fat is the total calories burned, regardless of the rate at which they are burned. So whether your approach is slow and steady or fast and furious, the results in terms of losing body fat will most likely be the same."
Mixing in some high-intensity intervals, however, will boost your cardiovascular fitness more than low-intensity continuous exercise. Experiment with each of the programs on the cardio machines in your gym and see which ones you like the best, Gaesser suggests. The variety will help keep you motivated too.