I have heard that the optimum target zone for weight loss is lower than the target zone for good cardio fitness and endurance. I have heard this from trainers, friends, and even see it written on fitness machines (they have a graphical depiction of your weight loss zone being lower than your cardiovascular zone). So my question is: Is this true?? How can it be? Where can I read more about this? It seems contradictory to lose less weight by training in a higher zone. Thanks for the help! Ron


Hello, This whole concept of an optimum target heart rate zone for weight or fat loss is very confusing so don't feel bad! It's really all a simple misuse of terms and a misunderstanding that burning fat calories exclusively will help you to lose weight faster. Let me try to explain the physiology behind it. The first problem occurs with the use of the term "optimum weight loss" in describing this optimum "fat burning" heart rate zone. This optimal fat burning zone is more of a question of how the human body uses calories to fuel a particular activity. It is very true that at the lower heart rate zones (55-65%) the human body will burn fat as the primary energy source. Thus, making this lower intensity heart rate zone the optimal fat burning zone. But, this is only part of the story! When the intensity moves up to 70-80%, your body will burn both fat and carbohydrates as an energy source. At this time it is important to say that it is of much greater importance to burn more "calories" not just fat calories when fat loss is the goal. Or, to put is another way. Burning 100 fat calories is not as good as burning 300 "overall" calories. Now, it's pretty simple to understand that training at a higher heart rate zone will burn more calories per unit of time (20 minute cardio session) than training at a lower heart rate zone. But, the lower the intensity of the exercise the greater the portion of those calories will come from fat. We need to remember however, that the goal is to burn CALORIES, not just fat calories. So, training at a higher intensity range will help you to reach your weight loss and fat loss goals faster. If you really like to train at a lower intensity, which is fine, just remember that you will have to train longer in order to burn the same amount of total calories had you been training at a higher intensity. Also, training at a higher heart rate zone will provide for a better cardiovascular conditioning affect than will lower intensity training. I hope my explanations have helped you to better understand the caloric burning differences between training at a lower verses higher heart rate zone. Now it becomes an issue of how you like to train, your overall health, and the time you have available for exercise in determining what heart rate zone you should to train at. Thanks for your question, Dan