Hype or Healthy: The “Fat-Burning Zone”

You may have heard about the “fat-burning zone,” which is the optimal heart rate to achieve while exercising to lose weight. Sustaining this peak heart rate during aerobic exercise can help you to lose weight faster and more efficiently than other forms of exercise. For this reason, some newer treadmills and ellipticals may indicate a “fat-burning zone” on their settings.

 

Heart Rate and Exercise

Exercise and diet are very important for losing weight and building muscle. But not all forms of exercise were created equally. Anaerobic exercise can help you burn calories and build muscle; however, aerobic exercise increases your heart rate and jumpstarts the weight loss process.

Doctors recommend at least 2.5 hours of aerobic exercise each week, ideally spaced throughout the week.¹ Aerobic exercise is important for keeping a strong and healthy heart. In addition, doctors also recommend anaerobic exercise for each muscle group at least twice a week. Anaerobic exercise helps to build and maintain muscle tone. Both aerobic and anaerobic exercise are important.

Aerobic exercise increases your heart rate. But what is a good heart rate to achieve? And for how long? That depends largely on your goal for working out. If you want to lose weight, you need to achieve a different heart rate than to build muscle or maintain your shape.

 

Ideal Heart Rate for Burning Fat

If you want to lose weight, you should be targeting the “fat-burning zone.” This is the ideal heart rate for eliminating excess fat.

There has been some controversy around whether or not a “fat-burning zone” even exists. A quick internet search will bring up articles claiming that the “fat-burning zone” is a myth. There may be some truth to these articles, as there is no one-size-fits-all “fat-burning zone.” Indeed, the setting on your treadmill might be a little misleading; however, scientists have studied the ideal heart rate for losing weight. (Hint, hint: there is one!)

For maximum weight loss, you should be targeting 68-88% of your maximum heart rate² (see below). When your heart rate reaches this level, your body metabolizes fat more efficiently, allowing you to lose weight faster!

The “fat-burning zone” setting on your treadmill or elliptical might give you different targets. Or it might have a static range that doesn’t account for individual differences in maximum heart rate. Make sure you pay attention to your heart rate and make sure you stay within reasonable limits for your age and level of physical fitness. If you’re unsure what your maximum heart rate is, talk to your doctor.

 

Ideal Heart Rate for Building Muscle

The ideal heart rate for aerobic conditioning (strengthening your heart and increasing physical fitness) is slightly different. For building muscle, you should only target 59-76% of your maximum heart rate.

If you notice, there is some overlap between the two targets. If you want to lose weight and increase fitness simultaneously, 68-76% of your maximum heart rate is optimal. This is the sweet spot where the two targets overlap.

When you exercise, regardless of your goals, you should strive to keep your heart rate within reasonable limits. Remember to determine your maximum heart rate or discuss it with your doctor before beginning a new exercise routine.

 

Cheat Sheet: Quick Facts About Heart Rate and Calories Burned

Your maximum heart rate is important for calculating where the “fat-burning zone” exists for you. The following numbers are averages.³ People with specific health conditions (especially heart or lung conditions) may have maximum heart rates that vary greatly. Also, consult your doctor before beginning a new exercise regimen.

• Age 20: 200 bpm
• Age 30: 190 bpm
• Age 40: 180 bpm
• Age 50: 170 bpm
• Age 60: 160 bpm
• Age 70: 150 bpm

 

Here is also a quick reference for the number of calories burned per hour by different types of exercise.⁴ The Mayo Clinic recommends restricting caloric intake by about 500 calories a day to lose a pound per week.¹ You can also burn those 500 calories through exercise (assuming your intake does not also increase!).

• Bicycling <10 mph: 292
• Elliptical, moderate-intensity: 365
• Hiking: 438
• Walking, 3 mph: 314
• Running, 5 mph: 606
• Swimming laps: 423
• Ballroom dancing: 219

References

1. Exercise for Weight Loss: Calories Burned in 1 Hour. Mayo Clinic. https://www.mayoclinic.org/healthy-lifestyle/weight-loss/in-depth/exercise/art-20050999. Accessed 9/17/2020.
2. Carey DG. Quantifying differences in the “fat burning” zone and the aerobic zone: Implications for training. J Strength Cond Res. 2009;23(7):2090-2095. DOI: 10.1519/JSC.0b013e3181bac5c5.
3. Target Heart Rates Chart. American Heart Association. https://www.heart.org/en/healthy-living/fitness/fitness-basics/target-heart-rates#.V5usxpMrLX8. Accessed 9/17/2020.
4. Compendium of Physical Activities. https://sites.google.com/site/compendiumofphysicalactivities/compendia. Accessed 9/17/2020.