Fat-Burning Heart Rate: What It Is and How to Calculate Yours

The image of a runner pounding the pavement at dawn or throwing down ropes at the gym has long been associated with maintaining a healthy weight. But not everyone sees a big drop in the scale from their workout efforts. That doesn't mean they aren't worth pursuing: physical activity is one of many factors that contribute to overall health. But if your primary goal is weight loss, you might want to start paying attention to your fat-burning heart rate during exercise.

Let's dive into what it means for a heart rate to be "fat burning," how to calculate it, and no matter if you're a triathlete or a casual gym-goer, how you can use it alongside a healthy diet and supplementing to optimize your overall fat burning and weight loss goals—and how it can help you improve your physical fitness.

What is a fat-burning heart rate?

To understand how heart rate affects fat burning, let's review some basic facts first. As you no doubt remember from grade-school biology, the heart is one of the body's hardest-working organs and is responsible for pumping blood throughout the body. It beats much faster during vigorous-intensity physical activity, and much slower during normal day-to-day activities.

Your heart rate is measured by something called BPM or beats per minute. A normal BPM number for adults over the age of 18 is roughly 60-100 BPM, but it can vary from one minute to the next. Though this is considered normal, it's worth noting that being outside this range doesn't necessarily mean there's anything wrong with you—everyone is different.

As its name implies, the fat-burning heart rate is the BPM number thought to be the most effective at achieving maximum fat-burning results. The maximal heart rate, similarly, is the highest BPM your cardiovascular system is capable of sustaining.

Because the higher your BPM, the more calories you burn in a single workout session, you might think that the best way to burn fat would be to get your heart beating as hard as possible—perhaps by hopping into the bear enclosure at the zoo and trying not to get eaten—but there's more to burning fat than simply maxing out your BPM. The nuances will come later, but first, let's get into the math behind calculating your fat-burning heart rate.

How do I calculate my fat-burning heart rate?

Your fat-burning heart rate varies from one person to the next and is impacted by factors like your age, overall health, fitness level, daily intake of calories and even time of day.

Still, calculating a general fat-burning heart rate is based around two different things: your max heart rate and resting heart rate.

To calculate your maximal heart rate, start by subtracting your age from 220. So, if you're 30 years old your maximal heart rate should be roughly 190, and if you're 70, it should be around 150. Once you have this number, you'll need to find your resting heart rate. The easiest way to do this is by checking your pulse when you're relaxed and counting the number of times your heart beats in a minute.

Once you have these numbers, you can figure out your fat-burning heart rate, which generally falls between the maximum heart rate and the resting heart rate. Specifically, multiply your maximum heart rate by 70% to find the upper end of your fat-burning heart rate, and multiply your maximum heart rate by 50% to find the lower end of your fat-burning heart rate. Right in between your upper and lower threshold is your heart rate Goldilocks zone, in which you have the best shot at burning fat.

Pro tip: Rather skip the math? The fat-burning heart rate zone usually corresponds to long-duration physical activity that is low-intensity or moderate-intensity in nature. If you do a low-impact activity like walking briskly for an hour while being able to carry on a conversation without getting winded, that's probably the right place to be for fat loss.

What are the different heart rate zones?

Now that you know what number to be looking for, here's an overview of the different anaerobic aerobic "zones" you can be in at any given point during a workout. The basic categories are numbered from 1-5 and vary in intensity and benefits:

• Zone 1:

  This is considered the lightest intensity, with your target heart rate at 50-60% of your maximum heart rate. You're more likely to be in this zone primarily during warm-up, cool-down, and recovery exercises. Staying in this zone won't put you in the fat-burning zone, but it is good for active recovery and helps increase blood flow and supports overall cardiovascular health.

• Zone 2:

  When you're in this heart rate zone, you've officially entered the fat-burning zone, where the target heart rate is 60-70% of the maximum heart rate. It's a lighter-intensity zone, but not as light as zone 1. Training in this heart rate zone can benefit your aerobic fitness, endurance and promote weight management and fat loss. During challenging workouts that have you pushing yourself, it's an accomplishment to be able to return to this zone without stopping your efforts entirely.

• Zone 3:

  Also good for fat burning, this zone usually correlates with moderate intensity, where the target heart rate is 70-80% of the maximum heart rate. Being in this zone is a great way to support your aerobic fitness and help you build endurance. In this zone, your body is still burning fat for energy while pushing it to its aerobic limits.

  Pro tip: Steady state cardio, where your heart rate stays more level and your body is still using fat as its main energy source, usually falls between zones 2 and 3.

• Zone 4:

  At this point in the workout, you've left the fat-burning zone and are pushing your limits! This zone is associated with very high-intensity and difficult workouts, with the target heart rate reaching between 80-90% of the maximum heart rate. Training in this zone is all about anaerobic capacity and the upper limits of energy the body can produce during this type of exercise. Those who focus on exercises in this zone are likely doing interval training or trying to improve their speed and performance.

• Zone 5:

  Maximum intensity, where the target heart rate is 90-100% of the maximum heart rate. Training in this zone means going all-out, aka exerting maximum effort. Most likely, you'll hit zone 5 as part of high-intensity interval training (HIIT), but any high-intensity workout might land you in this fat-burning zone for short periods of time. Being in zone 5 is all about maximum output and powerful athletic performance. It's also great for burning both calories and fat, although it's not sustainable—literally—for more than a few moments at a time.

What is the best heart rate to burn fat?

So, now that we know all about the different zones, we can finally answer the big question: What is the optimal fat-burning zone? You might be surprised to know that zone 2, which will have you pumping at 60 to 70% of your maximum heart rate, is what you'll want to target as your fat-burning zone. Here, the body makes increased use of its fat stores, the cardiovascular system also gets a good workout and you burn calories.

And science supports it. A study of aerobic exercise intensities found that heart rate reserve (HRR)—i.e., the difference between maximum and resting heart rate—was a good predictor of weight and body fat loss. Specifically, they found that the medium-intensity exercise (50-70% HRR) and high-intensity exercise (70-80%) groups had significantly more changes in body weight waist circumference, waist-to-hip ratio, and waist-to-height ratio than the light-intensity exercise (40-50%) group.

Is a higher heart rate better for weight loss?

A higher heart rate is not necessarily better for weight loss. The fat-burning zone thought to be best for burning fat is intense enough that your body will begin to use fat as its primary energy source, but not so intense that you exhaust yourself quickly. It's also thought that exercising at this heart rate zone will help sustain your workout for longer without feeling overly fatigued.

This corresponds to zone 2 discussed above, which will have your heart pumping at 60 to 70% of its maximum.

That having been said, it's important to note that this approach to weight loss might not be the best course of action for everyone. Some may need to increase exercise intensity for better long-term results. And, of course, any of these techniques will work better when paired with a well-balanced, high-protein diet and adequate sleep.

How long should your heart rate be in the fat-burning zone?

Though the answer to this question will depend a lot on the specifics of your circumstances, a good rule of thumb is to spend at least half an hour in the fat-burning heart zone to reap the fat-loss rewards.

Zooming out a bit, the CDC recommends a weekly minimum of 150 minutes of moderate-intensity activity or 75 minutes of vigorous-intensity exercise, plus at least two days a week of muscle-strengthening activities, like lifting weights.

References

• Burke K. "How to target heart rate training zones effectively." Colorado State University. February 2023. https://chhs.source.colostate.edu/how-to-target-heart-rate-training-zones-effectively/
• Chih-Hui C, et al. "Benefits of different intensity of aerobic exercise in modulating body composition among obese young adults: a pilot randomized controlled trial." Health Qual Life Outcomes. August 2017. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5571495/
• MacPherson, Rachel, "Fat Burning Heart Rate: Definition And Chart." Forbes. June 2023. https://www.forbes.com/health/body/fat-burning-heart-rate/
• "All About Heart Rate (Pulse)." American Heart Association. May 2023. https://www.heart.org/en/health-topics/high-blood-pressure/the-facts-about-high-blood-pressure/all-about-heart-rate-pulse
• "Finger On The Pulse: 5 Ways to Monitor Your Heart Rate." Garmin. December 2018. https://www.garmin.com/en-US/blog/fitness/5-ways-to-monitor-your-heart-rate/
• "Heart Rate Monitoring." Garmin. https://www.garmin.com/en-US/garmin-technology/health-science/heart-rate-monitoring/
• "How much physical activity do adults need?" Centers for Disease Control and Prevention. June 2022. https://www.cdc.gov/physicalactivity/basics/adults/index.htm