Woman checking up heart rate from smart watch

What Is The Heart Rate Fat-Burning Zone?


Billy Hughes
August 25, 2021

While you might feel like you’re in the zone when you reach a peak during your fitness routine, there’s a fat burning zone that you could be missing out on.

This requires working out at a certain heart rate in order to help your body burn more fat.

Do you have to endure high-intensity exercise in this zone?

Interestingly, the fat-burning zone is not just about working out vigorously in order to burn more calories. 

How is that possible? Here’s everything you need to know about the fat-burning zone and how it’s linked to heart rate before your next workout session. 

Heart Rate And Burning Fat – What’s The Connection? 

five heart rate zones

Your body uses glucose to fuel your muscles, with glycogen and fat being the two primary sources of it.

Fat needs to break down to produce glucose as well as carbon dioxide and water. Oxygen is what breaks down the fat stores or glycogen into glucose so that the muscles can use it as fuel.

Of course, the more energy you need, the more fuel your muscles will need, such as during a vigorous exercise session.

Your heart rate increases during exercise and works harder than normal to send your muscle cells oxygen so that they can break down more fat and glycogen to get the food – or fuel – that they require to perform.

When you’re pushing your heart rate higher and working hard at the gym, your maximum heart rate comes into play. This is defined as the highest heart rate that you can safely achieve during high-intensity exercise.

During this heart rate zone, as it’s called, you can burn more fat. But it’s not always possible to exercise at such a high intensity for longer workouts.

That’s why your fat-burning heart rate is actually between the two extremes of when you’re resting (when your heart rate is between 60 and 100 beats per minute) and when you’ve hit your maximum heart rate. 

How To Calculate Your Maximum Heart Rate And Fat-Burning Rate? 

what are five training zones

To work out what your maximum heart rate is, you need to subtract your age from the number 220. So, if you’re 35, your maximum heart rate will be 185 beats per minute.

On the other hand, if you’re 45, your maximum heart rate will be 175 beats per minute. Your maximum heart rate will decrease as you age. 

Now, if you want to figure out your fat-burning zone rate, you need to know your upper and lower limits. Your upper limit is 70 percent of your maximum heart rate, while your lower limit is 50 percent of your maximum heart rate.

So, if you’re 35, your upper limit will be 129.5 (which is 70 percent of 185 heart beats per minute) and your lower limit will be 92.5 (which is 50 percent of 185 heart beats per minute).

This gives you a range in which you can safely exercise. 

What about your heart rate reserve?

Another important number to know about is your heart rate reserve. Here’s how to calculate it.

  • First, to calculate your maximum heart rate you need to subtract your age from 220. 
  • Then, take your pulse when you’re at rest, such as first thing in the morning after waking up. Subtract this from your maximum heart rate. So, if your resting heart rate is 70 and your maximum heart rate is 170, you’ll have a heart rate reserve of 100.
  • This number will help you find your ideal heart rate range depending on how vigorous your exercise session. 
  • To calculate it for moderate-intensity exercise, you need to multiply your heart rate reserve number (100, for example) by 0.5 and 0.7. Then, add your resting heart rate to both of these numbers. So, if your heart rate reserve is 100, your target heart rate for moderate-intensity exercise will be between 120 and 140. 
  • To calculate your average target heart rate for when you’re doing high-intensity exercise, simply multiply your heart rate reserve by 0.7 and 0.85. Then, add the resting heart rate to these numbers. So, for example, if your heart rate reserve is 100, you’ll have a target heart rate for vigorous exercise that’s between 140 and 155 beats per minute.

Pro tip: If you want to take part in moderate-intensity exercises that will make you use between 50 and 70 percent of your maximum heart rate, you should do activities such as brisk walking, dancing, gardening, and biking at a leisurely pace. If you want to increase the intensity with more vigorous exercise so that you’ll use 70 to 85 percent of your maximum heart rate, you should participate in activities such as running, swimming laps, heavy garden work, and hiking uphill while wearing a heavy backpack. 

Does The Fat-Burning Zone Actually Work? 

are fat burning zones myth?

There has been talk about whether or not the fat-burning zone is actually useful for people who work out.

The important thing to know about this is that this fat-burning zone is limited. Generally, the higher your heart rate is, the more your body will burn fat compared to other sources of calories, like carbs.

But, that doesn’t mean you have to stay in the fat-burning zone all the time in order to burn as much fat and lose as much weight as possible.

Research has found that the ideal heart rate which enables the burning of fat is between 60.2 and 80 percent of your maximum heart rate.

The American Council on Exercise has also warned people about relying too much on the heart rate fat-burning zone, as calculating your maximum heart rate based on 220 isn’t that accurate.

There are various factors besides age which influence how fit a person really is. After all, not every person who’s the same age will have the same fitness level!

What Are The Four Heart Rate Training Zones? 

heart rate zones

There’s not just the fat-burning zone which you should be aware of if you want to take your fitness up a notch.

Here are other heart rate training zones to know about.

Zone 1

This zone consists of low-intensity exercise that boosts recovery and prepares you for working out in a higher heart-rate zone. Walking or cycling will be examples of these exercises because they enable you to control your heart rate easily. In this zone, you’ll be using 50 to 60 percent of your maximum heart rate.

Zone 2

This zone works 60 to 70 percent of your maximum heart rate. Exercise in this zone will also be light. It will enable you to work out at a lower intensity for longer periods of time. This zone is known for promoting endurance and in it your body improves its fat-burning ability.

Zone 3

This zone is when your heart rate is between 70 and 80 percent of your maximum heart rate. This is moderate-intensity exercise that improves blood circulation in the skeletal muscles and heart. 

Zone 4

This is when you work out to between 80 and 90 percent of your maximum heart rate, and the workout can feel tough! Some benefits of being in this zone include how your speed endurance will improve and your body will use carbohydrates for energy more efficiently.

Zone 5

The final zone is when you’re using 90 to 100 percent of your maximum heart rate. You’re putting in the most effort you can and your blood, heart, and lungs are working at their highest capacity. You won’t be able to work out for longer than a few minutes in this zone. Related Questions 

When is a high heart rate during exercise dangerous?

check your pulse and heart rate

If you work out with a heart rate that’s higher than your maximum heart rate for long periods of time, this can be dangerous. It can increase your risk of chest pain, arrhythmias, and discomfort, while making workout recovery poor.

How can you become more aware of your heart rate?

Invest in a heart rate monitor. Check it regularly during exercise so that if you’re in Zone 4 or higher continuously, you can slow yourself down.


If you want to improve your endurance and fitness, you will probably be interested to know what the heart rate fat-burning zone is all about.

In this article, we’ve explored everything you need to know about this zone as well as why it’s important but should be taken with a bit of moderation. With that in mind, we’ve also explored the four other fat-burning zones and what benefits they can offer.



Billy Hughes

Billy Hughes is a fitness trainer based out of New York. She has registered success in training clients at multiple fitness centers and thus aims to establish her module relevant to the post-pandemic era. Her space, Cerevellum.com, is an attempt towards encouraging and educating more people on the scope of indoor fitness. She believes the power of fitness can transform attitude, personality, and way of living. She also finds it rewarding to help people achieve their goals and make their lives better.