Do you exercise because you want to lose weight? If so, you've probably heard, or been told, that for best weight loss results you should work in your "fat burning zone" (about 60% to 70% of your maximum heart rate).
While lower intensity workouts are great for building endurance, they aren't always the best choice if your goal is to lose weight.
The body does burn a higher percentage of calories from fat in the fat burning zone or at lower intensities. However, at higher intensities (70-90% of your maximum heart rate), you burn a greater number of overall calories, which is what matters when it comes to losing weight. The chart below details the fat calories expended by a 130-pound woman during cardio exercise:
|Low Intensity - 60-65% MHR||High Intensity - 80-85% MHR|
|Total Calories expended per min.||4.86||6.86|
|Fat Calories expended per min.||2.43||2.7|
|Total Calories expended in 30 min.||146||206|
|Total Fat calories expended in 30 min.||73||82|
|Percentage of fat calories burned||50%||39.85%|
Source: From The 24/5 Complete Personal Training Manual, 24 Hour Fitness, 2000
In this example, the woman burns more total calories and more fat calories at a higher intensity. This isn't to say that low intensity exercise doesn't have it's place. In fact, endurance workouts should be a staple of a complete fitness program along with shorter, higher intensity workouts or interval workouts, which are a great way to burn calories and build endurance. To figure out your own target heart rate zone, you can use an online calculator or follow these detailed steps for calculating it on your own.