Does the Fat Burning Zone Really Exist?

Cardio equipment is full of fancy graphs and screens that tell you where your heart rate should be for “fat burning”. This may be the biggest myth of the fitness industry ever! So where exactly does this number come from? So in order to calculate your “fat burning” heart rate: subtract your age from 200 and multiply this number by 0.6. As long as your heart rate remains at this number, you’re burning fat!



According to the story, you apparently will burn more fat at this rate than if you trained at a much higher intensity. So what’s the point of working your body to the max, if you can keep it simple while burning fat? This has been a question for decades and many gurus have passed down misleading information regarding this fat burning zone. In this article, you will learn why this is a myth and how to train to burn more fat.



When you exercise, you burn carbohydrates (glycogen) and fat and the amount is correlated to the intensity of your workout. When training at 50% of your max heart rate, your body will burn 60% fat and 40% glycogen. When training at 75% of the max heart rate, you burn about 30% fat and 70% glycogen. So now you’re probably thinking that this makes no sense to call the fat burning zone a myth, after all we just defended it. Well now think about this:

Total Calories Matter

Regardless of what percentage of calories comes from fat and what comes from glycogen, you still must consider total calories burned! In order to lose weight, you must go by the simple equation; calories in vs. calories out! So let’s use running vs. jogging as an example.


According to various charts and exercise calculators, a 150 pound person will burn about 239 calories in 30 minutes of jogging. If they are running at 50% of their max heart rate they would be burning 143 calories from fat and 95 calories from glycogen. Now if the same person was running at a higher intensity let’s say 8mph, they would burn a total of 460 calories. Since this is probably about 75% of their max heart rate, 138 calories have come from fat, and 322 have come from glycogen. So you’re probably saying well this isn’t a big difference 143 vs. 138. But there’s still a major reason why this will all make sense.

The After Burn Effect

There is a phenomenon known as EPOC, excess post-exercise oxygen consumption. This basically states that after exercising, the body needs to use energy to return back to a balanced state. You will continue to burn more calories after the workout has been completed. So when you train at a higher intensity, it will take more energy to return to homeostasis than it would if you trained at a very low intensity. This concept is also known as the afterburn effect.


A study at Appalachian State University tested a group of males after a 45 minute high intensity workout session. In 14 hours post-workout, they burned an average of 190 additional calories when compared to non-training days.
So an recommended high intensity workout would be to do 10 second sprints for about 10-15 sets. While sprinting is a high-intensity anaerobic activity, the primary source of fuel is glucose. Scientists found that there is an oxidation of fatty acids after the activity. Going back to the EPOC more oxygen is being consumed, therefore fat is being burned.
Some more high intensity workouts can be found here.

Is Low-Intensity Aerobics Pointless ?

With that being said, there is a place for low intensity steady state cardio in your plan. This is because if your goal is to maintain or build muscle, doing high intensity exercise constantly will eventually result in a decrease of muscle mass. This is a lot of stress placed on the body. A typical schedule would be doing high intensity cardio 3 times per week, and low intensity steady state cardio up to twice per week. This is a good balance for burning calories.


While we now explained how to burn fat through cardiovascular exercise, we have yet to mention the importance of nutrition, after all you still need to eat less than you burn. So if you have a well-designed and balanced diet plan, you will be able to control how much time you want to spend doing cardio. Also remember that increasing muscle mass will have a slight increase in metabolism. So incorporate a strength-training regimen and you will greatly benefit and really start seeing your fat melting away!



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