The Fat Burning Heart Rate Zone + How To Calculate Your Zone 2 HR

If you look around at the setting people are using on cardio equipment at the gym, you’ll notice most are exercising in the “fat burning zone” with the ultimate goal of losing weight and burning fat.

But, what is the fat burning zone heart rate? Do you burn more fat in the fat burn zone vs cardio zone?

In this fat burning heart rate zone fitness guide, we will discuss what the target heart rate for fat burning zone workouts is, what is meant by the fat burn calories cardio zone, how to calculate the best heart rate to burn fat, and other great tips for fat burning workouts.

We will look at:

• What Is the Fat Burning Heart Rate Zone?
• Does Exercise In the Fat Burn Heart Rate Zone Burn More Fat Than the Cardio Zone?
• What Does a Heart Rate Fat Burning Zone Workout Mean?
• Is the Fat Burn vs Cardio Heart Rate Zone Better for Weight Loss?

Ready? 

Let’s jump in!

What Is the Fat Burning Heart Rate Zone?

Before we look specifically at the target heart rate to burn fat or the “fat burn heart rate zone,” what exactly do we mean by heart rate zone for fat burning?

Fitness professionals typically use five different heart rate zones to help quantify the intensity of exercise based on how fast your heart is beating during your workout relative to your maximum heart rate.

Most people don’t know their true maximum heart rate unless they do a VO2 max test or maximum heart rate test, so we typically estimate maximum heart rate based on age because there is an inverse linear relation in maximum heart rate.

Essentially, the older you get, the lower your maximum heart rate is in a fairly predictable manner.

This formula has quite a large margin of error, but it should serve as a decent estimation for most individuals. 

For example, if you are 40 years old, your age-predicted maximum heart rate is 220-40 = 180 bpm. 

So where does the fat burn heart rate zone fit in? 

Not all fitness professionals agree on a precise target heart rate range for the fat burning zone, but it is generally somewhere between 50 and 75% of your max heart rate or 60 and 75% of your max heart rate.

One study determined that maximal fat oxidation occurred at 54.2 percent of VO2 max, which corresponds to about 71 percent maximum heart rate.

The “cardio zone“ is also a little bit loose in terms of definition, but it’s usually somewhere between about 70 and 75% to 85/88% of your maximum heart rate.

Does Exercise In the Fat Burn Heart Rate Zone Burn More Fat Than the Cardio Zone?

While the target heart rate for fat burning zone workouts is generally somewhere between 60 and 75% of your maximum heart rate, does that mean that you don’t burn fat in the cardio zone or that the fat burning heart rate zone is better for losing weight than the cardio zone?

Not exactly. 

There is a lot of confusion about whether the fat burn vs cardio zone burns more fat and is better for weight loss.

Even though fitness professionals use the term “fat burn heart rate zone,” exercise can help you lose body fat in several ways. 

1. To fuel your muscles when you exercise, your body burns stored fat to provide the calories necessary to generate ATP (energy for your muscles to contract).
2. Following a consistent workout routine can help you lose fat if you’re generating a caloric deficit (burning more calories in the day with your workouts, BMR, and physical activity compared to the number of calories that you are eating).
3. Certain types of workouts increase your metabolic rate and affect your hormones, which can help you burn more calories, even at rest, ultimately supporting fat loss over time.

The “fat burning heart rate zone” is related to the first of these three listed ways in which exercise primarily supports fat loss. 

Let’s look at this in more detail:

What Does a Heart Rate Fat Burning Zone Workout Mean?

Basically, fat burning heart rate zone workouts are performed at the intensity at which you are maximizing how much body fat you are burning. 

So, in a fat-burn zone workout, your body is burning a higher percentage of the calories that you need for that exercise from fat rather than from carbohydrates.

But, what does this mean, exactly?

Any type of physical activity or exercise requires your muscles to contract and your heart to beat harder and faster, all of which require energy.

To create this energy, there are various metabolic pathways that turn stored fuel into usable energy for your muscles (ATP). 

This stored fuel comes from a combination of stored carbohydrates (glycogen in muscles and the liver), stored fat (triglycerides in adipose, or fat, tissue), and stored protein in muscle tissue.

At pretty much any given exercise intensity, you’re burning some of every type of fuel to get the calories needed to create ATP.

By and large, carbohydrates and fat are the primary fuel sources for the muscles during exercise, with a much smaller contribution of calories for exercise coming from protein.

This is unless you are in a state of starvation or following an insufficient diet, exercising extremely intensely, or doing very long workouts.

Generally speaking, protein usually provides less than 10% of the total energy needed for exercise except in extreme situations such as starvation, ketosis, or very long and intense workouts, so it is not usually factored into determining calories from carbs vs fat during exercise.

That aside, the relative percentage of carbohydrates vs fat burning as the fuel your body oxidizes for energy depends on the intensity and duration of the workout.

As the exercise intensity increases, the relative percentage of carbohydrates increases, and the percentage of calories coming from fat decreases.

Therefore, when we look at the five typical heart rate zones for exercise, your muscles are primarily burning fat for fuel when you are doing workouts with your heart rate in zone 1 or zone 2, whereas more glycogen (stored carbs) is burned for workouts in zones 3, 4, and 5.

This is why fat burn zone vs cardio zone workouts are done at a lower heart rate. 

Said another way, and simplified to some degree, at lower intensities of exercise, fat is the primary fuel. That’s why exercise machines that have a pre-programmed workout in the “fat-burning zone” have you moving at a slower pace or easier intensity than cardio zone workouts.

Is the Fat Burn vs Cardio Heart Rate Zone Better for Weight Loss?

If you are trying to maximize how much fat you burn, exercising in the fat burning heart rate zone may seem like the most effective approach, but this isn’t necessarily the case.

When you work out more vigorously, although the percentage of calories from burning carbs is higher, and the lower your heart rate during exercise, the greater the percentage of calories do come from fat, vigorous exercise burns a greater number of calories overall.

Because a caloric deficit is necessary to ultimately lose fat, in almost all cases, a more vigorous or intense workout in the cardio vs fat burn heart rate zone will burn more total calories and more calories from fat, even though the relative percentage of these calories from fat decreases.

What this means practically is that even if you are working out above the target heart rate zone for fat burning, you still might burn more calories from fat during an intense workout.

Consider the following scenario:

If you ride a stationary bike at a low intensity (heart rate in zone 2) for 30 minutes, you might burn 200 calories, of which 60% come from fat, and 40% come from carbohydrates.

Therefore, in this example scenario, you would burn 120 calories from fat and 80 calories from carbohydrates for your workout.

Then, imagine you do a hard workout on an exercise bike where your heart rate is mostly in the cardio vs fat burn zone (zones 3-5). 

Again, you bike for 30 minutes, but this time, because you are cycling much harder and your heart rate is higher, you burn 400 calories in 30 minutes.

Because the exercise intensity was higher, 60% of the energy came from carbs, and 40% came from fat.

This means that the vigorous bike workout burned 240 calories from carbohydrates and 160 calories from fat. 

Therefore, even though the percentage of calories from fat was lower, you still burned more calories from fat than you did during the low-intensity “fat-burning heart rate zone” workout.

Plus, regardless of whether the calories you are burning during exercise come from fat vs carbs/glycogen, all that matters for losing body fat is the total number of calories you burn: as long as you create a caloric deficit, you will lose fat.

A caloric deficit of 3,500 calories will result in one pound of fat loss.

Finally, more intense exercise, such as HIIT, can help boost your metabolism, which can also contribute to burning more calories and losing more fat over time.

It is important to keep in mind that although exercising in the “fat burn heart rate zone“ will not necessarily burn more body fat in the long term than incorporating more vigorous workouts, your workout routine should include a balanced mix of cardio performed at different intensities. 

Zone 2 training, or the “fat burning zone,“ has plenty of other benefits and will help your body recover from more intense exercise.

To learn more about heart rate training, check out our guide to how to calculate your heart rate zones here.