Fat Burning zone vs Cardio zone

Many people are confused about fat burning zone and cardio training zone. Confusion is about how we   burn more fat in fat burning zone, or aerobic burning zone, which is an easier zone to do the workout. Let me discuss a little more on this issue.


What is fat burning zone and cardio zone
When you just walk at a good speed, and your heart beat is within 60 to 70 percentage of your maximum heart rate, you are in fat burning zone. At this zone, you can take breath easily, and should not feel much tired. If you start to increase your pace and start to run, your heart rate will increase, and reaches as high as 150-160 per minutes, you are entering cardio training zone.

Fat burning zone and cardio zone myth

Fat burning zone and cardio zone these two confusing terms have led many people to believe that compared to cardio zone they can burn more fat in fat burning zone. So why should we exercise hard when low intensity exercise burns more fat?

Yes, it is  true that you burn higher percentage of fat in fat burning zone, but total calories you burn in fat burning zone is much lower than that in cardio training zone. How? Let me give you an easy calculation. Suppose you burn 100 calories in walking, and 70% of that comes from fat burning. So you burn 70 calories on fat. Now on the same time you walked, you can burn around 200 calories if you do the workout in cardio training zone. So here main body uses mainly carbohydrate for its energy. So suppose you burn around only 40% (actual percentage depends on your speed), so still it will be 200X.40 = 80 calories. So you are still burning more fat during cardio zone workout.


How fat burning zone and cardio zone works

In any exercise we use calories. So calories come from where? There are two sources, one is fat and the other is glycogen. Glycogen is stored carbohydrate in our body.

As I mentioned above during low intensity exercise your heart beat is within 60 to 70 percent of your maximum heart rate. During this type of exercise around 60-70% calories come from fat and 30-40% come from glycogen, in other words from stored carbohydrate. This is why it’s known as fat burning zone.


But during intense exercise or in cardio zone where your heart rate is around 75% of your maximum heart rate 35% calorie come from fat and 65% from carbohydrate.


Let’s discuss, what is the meaning of these data

15 Minutes of exercise

Calories burnt from fat

Calories burnt from glycogen

Total calorie burnt

Low intensity (Fat burning zone)




High intensity

(cardio zone)




Here I have two points:

  • From the table above you see we are burning more fat during high intensity exercise.
  • Your concern should not be fat burning. Calorie burning is your ultimate goal. Because failing to burn enough calories means you are not getting flat stomach and getting overweight.


Bonus: there is another point to note, fat burning zone virtually has no afterburn effect, on the other hand you continue to burn calories for some times after intense exercise (cardio zone).

So if running is not difficult for you, it is always a better option.

Go to Slow Long Distance walk page.

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