FitMethod

It is time to set the record straight: the “fat burning zone” is a myth. Low intensity cardiovascular training is not the best way to lose fat. That’s a common misconception. Here’s why:
It is true that fats are the main energy source in low intensity workouts (60-65% of the maximum heart rate). About 55% of the total calories expended come from fat*. On the other hand, only 15% of the total calories expended in high intensity workouts (80-90% of the maximum heart rate) come from fat*. This has led some to believe that it is more efficient to stick to a low intensity training when trying to get rid of fat. However, there is another factor that needs to be taken into account and that is the total amount of calories burned. More calories are expended during high intensity workouts than low intensity ones. This means the following: even though fat makes a greater percentage contribution to total energy metabolism during light versus intense aerobic activity, a large total amount of fat is burned during higher intensity aerobic exercise.

Let’s take a look at this mathematically:

High Intensity Workout (30 minutes)= 500 calories expended. 500 x .15 (15% from fat)= 75 calories from fat.

Low Intensity Workout (30 minutes)= 100 calories expended. 100 x .55 (55% from fat)= 55 calories from fat.

The numbers speak for themselves. So when its time to get rid of that stubborn fat, increase your intensity and forget about the non-sense of the fat-burning zone.

*McArdle, Katch & Katch, Sports and Exercise Nutrition, Lippincott, Williams & Wilkins, Philadelphia, 1999.