Fat Burn Zone
Posted on February 24, 2015
Fat burn zone – is it a myth?
Many modern machines have a titillating fat burn zone or workout function. What is it and should you use it?
I would first preface this by saying that calculating calories burnt during exercise is a futile practice both in effectiveness and in purpose. We can’t do it very well and it should not be the goal of any workout. See “what is the best cardio” for more information on this.
The fat burn zone is a low to moderate exercise intensity zone. It’s usually based on heart rate and sits around 60-70% of maximum heart rate, a little below the aerobic zone. There are a few reasons why exercising in the fat burning zone may be a bad idea.
First, theoretically you use more fat as a percentage of caloric use at lower intensities than higher intensity activity and thus is where the whole fat burn zone came to be in the first place. The problem is that even if the percentage of fat used as energy is lower in higher intensity exercise, your metabolic rate is so elevated that it makes up for it. You could burn more total fat calories with higher intensity than low intensity workouts and more total calories by a substantial margin.
Second; substrate utilization (burning fat or carbohydrate) can only be accurately measure with the same open or closed circuit spirometry equipment I mentioned in the last post. It’sinfluenced by circadian rhythms, nutrition and medication. Figuring out if you burned fat from one workout to another isn’t how long term weight loss works.
Third; burning through stored carbohydrates (muscle or liver glycogen) allows you to use dietary carbohydrates more effectively and increases insulin sensitivity which in and of itself can be a very useful adaption for heath and weight loss. Again, higher intensity workouts prove superior to lower intensity workouts.
Finally; cardiovascular training does not itself lead to fat loss or even weight loss without a concomitant change in diet. You can research this more with this resource . However, don’t despair, by using High Intensity Interval Training you can lead to more favorable body composition changes if this is the reason that brings you to read this article in the first place.
