If you have ever set foot on a treadmill, stepper or elliptical trainer, you have probably noticed a little graph of heart rate zones by the control buttons. Between the ‘cardiovascular training zone’ and the ‘warm-up zone’ is the ‘fat burning zone’. If your goal at the gym is to shed a few pounds, you might be tempted to cruise at this low intensity exercise level.
I have written an article on this topic before, but I still get asked regularly if working at a low intensity is best for weight loss. I still hear of trainers who tell their clients to stay within a low heart rate zone to effectively burn fat and lose weight.
The fat burning zone theory gained popularity based on the fact that you use a higher percentage of fat as fuel at lower exercise intensities. As the exercise intensity increases, so does the body’s use of carbohydrates as fuel. One could think, therefore, that lower intensity exercise will help them lose body fat. This logic may seem sound, but is flawed.
If that fat burning zone was true, not exercising would cause the greatest amount of weight loss since you burn the highest proportion of fat calories while at rest. Of course, this is not the case. To lose body fat, you must be on an exercise and nutrition plan that creates a calorie deficit. Exercising at high intensities burns more calories, and therefore burns more body fat.
Revving up your workouts beyond the fat burning zone has other benefits. First, your fitness level will get a boost. Whether you maintain a high intensity load during the entire workout (called steady state workouts) or do interval training, your fitness level will improve faster, making it easier to keep up with your kids, play a game of soccer or hike up Teapot Hill. Next, high intensity workouts heighten your metabolism for the rest of the day. Because it takes longer to recover from hard workouts, you burn extra calories during the hours after exercise. Finally, working harder means you don’t have to spend as many hours at the gym. Most people have limited time to spend working out. Working out at a high intensity allows you to burn the same amount of calories in a shorter amount of time versus a low intensity workout.
If you are new to exercise, or have certain conditions such as high blood pressure or diabetes or have joint pain, low to moderate intensity exercise is a great place to start, and perhaps stay. If you are able to work at higher intensities, pick up the pace to maximize your time spent doing cardio exercise. If you want to lose weight quickly and effectively without spending hours at the gym, get out of the fat burning zone!