Learn how to calculate your target heart rate and uncover the best exercise intensities for losing fat and burning calories.
With fitness trackers more popular than ever, it seems everyone is looking to optimize their health through specific insights and data. And one idea that’s come up over and over again in the fitness world is: “the fat burning heart rate zone.” But is it real?
While there is a lot of talk about this specific heart rate zone for burning fat optimally, we’re going to uncover why you need to know the full picture on heart rate training zones and exercise output before choosing a certain type of exercise intensity just for losing fat.
Before we get there, let’s do a quick overview of your heart rate, maximum heart rate, and target heart rate. Although it’s not imperative to have these exact numbers in order to exercise and lose fat, it’s still good to have an understanding of what these terms mean.
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Your heart rate is the rate at which your heart beats. And if you monitor your heart rate during exercise, you can estimate how hard your heart is working, which is directly correlated with how much oxygen you are using.
Based on how hard you’re exercising, you can figure out which heart rate zone you’re working in. And knowing which heart rate zone you’re working in can tell you what is happening in and to your body based on your exertion levels.
You can calculate your heart rate manually or with a heart rate monitor, like the fitness tracker you may be wearing on your wrist right now.
To calculate your heart rate manually, place your index and middle fingers on your wrist, close to your palm, just down from your thumb. Move your fingers until they’re just over your artery and you can feel a pulse. This pulse is created by blood moving through the arteries each time the heart contracts, so it is a direct reflection of your heart rate.
Once you’ve found the pulse, apply very gentle pressure on that area. Then, count how many pulses you feel during the course of 10 seconds, with the first pulse starting at the count of zero. Multiply that number by six to get the amount of times your heart is beating in a one-minute period. This is your current heart rate. In order to get your resting heart rate, you would complete this heart rate check shortly after waking.
There are a number of things that can affect your heart rate, including exercise, dehydration, temperature of your environment, and, of course, your cardiorespiratory fitness.
In order to figure out which heart rate training zone you’re working in, you first need to know your maximum heart rate. This is the most output your heart can handle during exercise.
The easiest way to calculate your maximum heart rate is 220 minus your age. While this is a very general tool, it is not the most specific and exact. It’s difficult to get someone’s actual maximum heart rate, because that would require field testing someone’s heart at their actual maximum exercise output, which is cumbersome. For these purposes, 220 minus age is a good starting point, knowing that not everyone of the same age has the same maximum heart rate (therefore there is a margin of error).
<p class="pro-tip">220 - [age] = Maximum heart rate (bpm)</p>
As an example, someone who is 25 would find their maximum heart rate like this:
<p class="pro-tip">220 - 25 = 195 bpm<br/><strong>195 bpm</strong> is the maximum heart rate.</p>
The target heart rate is where you want to be working in order to get into a particular training zone. To calculate your target heart rate, you need to find the difference between your maximum heart rate and your resting heart rate, then you can multiply this by your desired heart rate.
<p class="pro-tip"><strong>Target Heart Rate (bpm)</strong><br/><br/>Maximum Heart Rate x Target Heart Rate % + Resting Heart Rate </p>
As an example, someone who is 25 with a resting heart rate of 40 (which is very good) and wants to train at 85% of maximum intensity would find their target heart rate like this:
<p class="pro-tip">220 - 25 = 195 (maximum heart rate)<br/>195 - 40 (resting heart rate) = 155<br/>155 x 85% = 132<br/>132 + 40 = 172 bpm<br/><br/><strong>172 is the target heart rate.</strong></p>
The heart rate training zones are certain intensities of exercise typically expressed as a percentage of your maximum heart rate. You’d want to get your target heart rate to fall into the percentage you’re trying to reach.
With the popularity of integrating technology into training, more people are striving to stay in certain zones for specific durations. Exercise studios and fitness apps have different specifications for zones, ranging from three to even six zones, and these zone delineations can vary greatly.
For instance, if you attend an Orangetheory Fitness class, you’re sure to see large TV monitors in the studio covered with colored-coded heart-rate zones of the participants. There is some science behind this method, because your heart rate does correlate directly with your output.
To keep it simple, here is the National Academy of Sports Medicine (NASM) three-zone guide:
In NASM periodized-training programs, certified personal trainers will guide their clients on how much exercise to do in each heart rate training zone in order to meet their fitness goals. And each training zone has its benefits.
Now, let’s get to the bottom of the training zone we’re all the most interested in: the fat burning heart rate zone.
The fat burning heart rate zone would fall just below and slightly into Zone 1 from the NASM three-zone guide above, and it could be slightly different in each individual. Technically, you can even burn fat at rest, but the fat burning heart rate zone is usually around 55–65% of your maximum heart rate<sup>1</sup>.
The term “fat burning heart rate zone” comes from the fact that when you do lower-intensity or steady-state exercise, your body uses mostly stored fat for energy. So yes, you are burning more fat when working in this zone.
Whereas, when you work with more intensity during exercise, your body uses more carbohydrates for energy—but it also uses fat at the same time.
“The fat-burning zone is the lower-end of your exertion intensity levels, when your body is metabolizing fat as fuel first—something like walking would be in the fat-burning zone,” says Pete McCall, ACE certified personal trainer and the host of the All About Fitness Podcast.
That’s where the idea of this “fat-burning zone” was coined, and it has encouraged some to take the name at face value and try to keep their workouts in this lower end of intensity. However, this can be a bit misleading.
While stored fat fuels lower-intensity exercise on the spot, this does not take into account the fact that higher-intensity exercise also burns fat during and after exercise. And higher-intensity exercise also creates a greater overall caloric burn, both through burning fat and burning carbohydrates at the same time.
We have to look at the full picture of exercise output over time, rather than the initial burning of fat in the moment. Yes, lower-intensity exercise burns fat in the fat burning heart rate zone, but higher-intensity exercise in the aerobic heart rate zone also burns fat—it’s just not its primary source.
That’s why, if it’s within your ability levels to do harder exercise in order to lose fat, you’ll get better results pushing into the higher zones than you would if you stay in the lower fat burning heart rate zone.
Higher-intensity exercise done outside of the fat burning heart rate zone offers additional benefits.
EPOC or excess post-exercise oxygen consumption is when the body’s oxygen consumption remains elevated after a tough workout. During this time, the metabolism is elevated and fat burning takes place<sup>2</sup>. This is also known as the after-burn period.
“Think about finishing a long drive and turning off your car. The engine will stay hot for a while. And that’s what’s happening with EPOC,” says McCall. “Your body is using more oxygen to return back to a resting state after exercise, and it’s also metabolizing new energy and removing byproducts from the muscle cells.
“While it’s hard to quantify exactly, the body may burn approximately an extra 200 calories over the course of 12 hours during EPOC,” McCall continues. “It’s not significant, but it’s something.”
Those extra calories burned can result in fat loss, which happens long after your cooldown. And this is just another reason why the fat burning heart rate zone may not be the best (or only) choice for targeting overall fat loss.
We know too much fat on the body is bad for your overall health, but not all fat is bad. Most people want to burn fat to improve their appearance, but focus on exercise output instead for better results.
“Rather than worrying about your heart rate, it’s more important to measure your breath during exercise,” says McCall. “If you are breathing quickly and can only say a couple of words during exercise and not a full sentence, then you are expending more net energy, which will ultimately result in more fat burning than a less-intense workout [would].”
According to McCall, the body burns about five calories to use one liter of oxygen, and oxygen consumption goes up the more muscles you recruit. He says that working at around 75–80% of your maximum heart rate will give you this training effect. And this zone is above the fat burning heart rate zone.
McCall gave this example of exercising in the fat burning heart rate zone or exercising above the fat burning heart rate zone:
<p class="pro-tip">If fat loss is your goal, you’d probably want to choose the higher-intensity 7-mile run for a better overall energy expenditure. This is where we don’t need to be as concerned with hitting the fat burning zone because you’ll still burn fat from the higher-intensity exercise.</p>
Yet, as a reminder, if you’re unable to run or would prefer a walk, then walking would be a better choice for you at that moment. Exercise still provides myriad health benefits, no matter the heart rate zone.
And you can also do a combination of both intensities of exercise in your workout program.
In one study of 36 runners, it was found that training for fat burning and aerobic fitness are not mutually exclusive and can be done at the same time<sup>3</sup>. The exercisers worked at 60–80% of their maximum heart rates and were able to achieve both maximal fat burning and improve aerobic fitness in their treadmill sessions. The study also cited that when working in the higher end of their maximum heart rate zones, more calories were expended overall and an after-burn did take place. But both intensities of exercise were beneficial.
If you’re into the numbers and enjoy knowing exactly which zone you’re working in, then do it. But for most people, you don’t need to put as much of an emphasis on your actual heart rate. Instead, focus on your breath to measure your exercise output.
“As soon as you start exercising at a higher intensity and you start burning carbohydrates, you’ll have to exhale carbon dioxide,” says McCall. “You are burning more calories when you’re breathing hard, but you’ll still be burning fat too.”
Although we often like to think that fat can disappear on its own or turn into sweat, it actually leaves the body through the breath via carbon dioxide so that’s where the importance of the breath really comes into play<sup>1</sup>.
The talk test is a great tool to use to measure your intensity. If you’re not able to check your heart rate in the moment, see if you can say a full sentence while exercising. If you’re only able to speak a few words because you’re breathing heavily, then you’ve reached a great place for exertion—above the fat-burning zone but burning both carbohydrates and fat. This effort would likely fall within that 75–80% of your maximum heart rate zone that McCall referenced earlier.
“When it comes to fat burning in men and women, there’s not much difference, other than the fact that women have a slightly different size heart and different hormones,” says McCall. “The physiology works mostly the same.”
Based on one study of 11 men comparing intermittent exercise throughout the day—pre-meal exercise and post-meal exercise—there’s no wide consensus on which is the best to lower glucose. However, the study found that brief intermittent exercise throughout the day was more helpful in lowering glucose spikes around breakfast, specifically<sup>4</sup>.
This study also confirms that exercise can, and will, at any time, support lowering glucose spikes. Both low- and high-intensity exercise can blunt glucose spikes. And individuals should try different intensities to see how their bodies respond.
Once again, rather than being concerned about a particular target heart rate or heart rate training zone in order to lower a glucose spike, just get moving. Exercise enhances a glucose-stabilizing lifestyle, which is a tool to optimize your health.
If you’re interested in losing fat and changing your body, you’ll need a combination of the right nutrient-dense diet and exercise (you can read more about nutrient-dense food here).
While burning calories may be your biggest goal, you’ll also want to consider incorporating both cardiovascular and resistance training elements into your weekly workout routine for the best overall results.
Even though it sounds great to focus on a singular fat burning heart rate zone, it’s actually better to vary your exercise intensities. If you have a choice, the more-intense workout will result in a higher overall caloric burn, energy expenditure, oxygen consumption, and fat loss.
But the best exercise program for you is one that you will actually follow. It’s ideal to try out different formats and find what works for you and your lifestyle. If you’re into the numbers, feel free to monitor your heart rate closely. But if you’d rather just move, assessing your breathing can also be an excellent way to gauge your output.
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