Learn why doing your cardio workout only in the fat burning zone will NOT achieve the greatest fat loss results!
Have you ever wondered what the charts on cardio equipment mean that identify whether you are exercising in the fat burning zone vs. the cardio zone based on your age and heart rate? Well, it all comes down to the intensity of your workout. The fat burning zone typically refers to low to moderate intensity (continuous) exercise while the cardio zone is typically referring to moderate to high intensity (continuous) exercise. So which one is better?
Back in the 1980’s, it was discovered that performing continuous exercise at a low to moderate intensity will require your body to burn more calories from fat sources, hence the name fat burning zone. Once a person exercises at a higher intensity and therefore enters the cardio zone, a lower percentage of calories burned come from fat sources and your body starts to use mainly glycogen (a usable form of carbohydrates). These findings started a public obsession to only exercise in the fat burning zone. After all, burning that excess fat is what we are all striving for, isn’t it?! But how effective is this obsession really? Let’s look at these findings in a real-life example and see whether this fat burning zone is really the magic trick to getting rid of those extra pounds of body fat once and for all.
Let me start by saying that both of these findings are in fact true. In a low to moderate intensity workout, most calories burned come from fat sources while glycogen is the main energy source during higher intensity workouts. HOWEVER, when we are just sitting on the sofa watching TV (another low intensity activity), our bodies also mainly use fat sources for energy. But that type of activity sure isn’t turning us into lean and toned bodies. That’s because weight loss, and therefore the loss of excess body fat, is determined by a simple mathematical equation: Calories in have to be less than calories out! 
In comparison, the fat burning zone may use a higher percentage of calories from fat sources; yet exercising in the cardio zone burns a greater total amount of calories. To paint a better picture of this controversy, let’s do the math and see which method burns more overall calories and total fat calories – the fat burning zone or the cardio zone:
Scenario 1)
A 200lbs person, walking at a speed of 2.5mph, burns approximately 106 calories for 30 minutes. At this moderate intensity, a.k.a. in the fat burning zone, about 50% of calories burned come from fat sources. That means, about 53 out of 106 calories come from body fat.
Scenario 2)
That same 200lbs person is now running at a speed of 6.0mph for 30 minutes. Now that identical person burns approximately 354 calories. At this higher intensity, a.k.a. in the cardio zone, about 30% of calories burned come from fat sources. In this case, about 106 out of 354 calories come from body fat.
Did you notice the difference? In the fat burning zone, this person may burn a greater percentage of calories from fat but in the cardio zone, a greater total number of fat calories is burned. Additionally, the overall total amount of calories burned is far greater in the cardio zone and therefore will achieve better fat loss results. (Remember, it takes a caloric deficit of 3,500 calories to lose one pound of body fat.) Now take it a step further: Even after 1 hour of walking at 2.5mph, this person is still not burning as many calories (total and from fat sources) as they would in 30 minutes at 6.0mph.
The verdict… the intensity of your workout along with proper nutrition will pave the way to your weight loss success! Think of it as accomplishing more in a shorter amount of time.
How does your cardio workout measure up? Post your comments below.