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

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If you exercise because you want to lose weight, you've probably heard or been told that, for the best results, you should work in your "fat-burning zone." Your fat-burning zone refers to the workout intensity that gets your body to burn primarily fat for fuel and is often measured using heart rate.

Target Heart Rate Zones

Your resting heart rate (RHR) is the number of times your heart beats per minute (BPM) while at rest. You can determine this rate by placing your index finger on your your wrist or neck and counting the beats you feel for 60 seconds. A healthy RHR is usually between 60 to 100 BPM.??

Your maximum heart rate (MHR), or the maximum number of times your heart can beat in a minute, is calculated by subtracting your age from the number 220. For example, if you are 30-years-old, your MHR is 190 (220 - 30 = 190).

When it comes to exercise, particularly cardio exercise, there are different? heart-rate zones that equate to different levels of intensity. These levels are based on MHR and determine which energy systems your body uses during exercise, directly affecting how many calories you burn.

 Workout Intensity Heart Rate How to Identify
via the Talk Test 
 
Low
50-70% of MHR Can talk with relative ease

Moderate
70-80% of MHR Can talk, but only a few words at a time

High
80-90% of MHR Talking is difficult

Maximum
90-100% of MHR Cannot talk at all

Fat-Burning Heart Rate

The fat-burning zone is the lowest intensity. Why? Because the body relies on more stored fat (versus carbs) as its primary fuel source when you work at a lower intensity compared to a higher intensity.?????

Some people have translated this to mean that you actually burn more fat when you work at a lower intensity, but that's a bit of a misconception. In reality, picking up the pace will torch more total calories—and ultimately more fat—in less time.????? And it's the number of calories you burn overall that leads to the most weight (and fat) loss.

To give you an example, the chart below details both the total calories and the fat calories expended by a 130-pound woman during cardio exercise. As you'll see, the woman burns more total calories and more fat calories when working out at a higher intensity.

  Low Intensity
(60% to 65% MHR)
High Intensity
(80% to 85% MHR)
Total calories burned per minute 4.86 6.86
Fat calories burned per minute 2.43 2.7
Total calories burned in 30 minutes 146 206
Total fat calories burned in 30 minutes 73 82
Percentage of fat calories burned 50% 39.85%

Now, this isn't to say that low-intensity exercise doesn't have its place, especially if you're just starting out and can't sustain a faster pace.?? If you go slower, you may be able to exercise a lot longer, so you'll end up burning more calories and fat that way. 

Even for more advanced exercisers, endurance workouts should be a staple of a complete fitness program along with short, high-intensity interval workouts. Interval training where you alternate high-intensity exercise with low-intensity recovery periods is proven to increase fitness and burn more calories than steady-state cardio.??

While lower-intensity workouts are great for building endurance, you need to work harder during some workouts if you really want to burn fat and lose weight. Thus, varying workout intensity, such as high intensity interval training and steady state cardio, are important for a balanced fitness program.

Structuring Cardio Workouts

If you want to lose weight, a general cardio schedule would include workouts at a variety of intensities within your target heart rate zone.???? For instance, if you're doing five cardio workouts a week, you might have one high-intensity workout, one lower-intensity workout, and three somewhere in the middle.

Low intensity cardio helps you build more stamina because you can work out for longer periods of time. This, in turn builds endurance and increases the amount of calories you burn overall.

A beginner cardio program lets you slowly build endurance while getting you a bit out of your comfort zone. That way, you don't have to spend an entire workout miserable, yet you'll still challenge yourself, which will burn more calories. Below is a sample program that will help get you started. 

Day Workout Intensity Time
Monday Beginner-Interval Workout Level 1 Up to 21 minutes
Tuesday Low-Intensity Walking 10 to 20 minutes
Wednesday Rest  
Thursday Cardio-Endurance Workout Up to 35 minutes
Friday Rest  
Saturday Beginner Interval Workout Level 2 Up to 25 minutes
Sunday Low-Intensity Walking 10 to 20 minutes

The key is to start with what you can handle and slowly build from there. If you're just getting started, don't worry too much about how hard you're working. Focus more on making exercise a habit you can manage on a regular basis.

Other Factors to Consider

Exercise is not the only way to burn excess fat. You can also get your body to shed fat by eating a balanced diet, watching your portion sizes, drinking plenty of water, and getting enough sleep. The more avenues you use, the faster you drop the extra weight.

Plus, burning fat or losing weight is not the only goal of cardiovascular exercise. Working out regularly has been found to lower your resting heart rate, which also reduces your risk of dying early from cardiovascular disease.???

A Word from Verywell

Everyone's fitness level is different. Additionally, certain medications can affect a person's heart rate. Therefore, before beginning any new workout program, you should consult with your doctor to determine whether that exercise is safe for you and, if it is, what your goal heart rate should be.

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  3. American Council on Exercise. I’ve Heard That Performing Aerobic Workouts at a Low Intensity Is Best for Losing Body Fat–Is That True?.

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