If your goal during exercise is to burn the highest percentage of calories from fat, make sure you stay in your calculated target heart rate range for fat burn or, in other words, your “fat burning zone." When you exercise in your fat burning zone, you use a greater percentage of calories from fat than at other heart rate zones. You reach your typical fat burning zone when your heart rate is at 55 percent to 70 percent of your maximum heart rate.
Heart Rate Monitoring Methods
Your heart rate is the number of times your heart contracts in a minute and is typically listed as beats per minute. You can determine your heart rate in a variety of ways. Wearing a heart rate monitor, which is composed of some type of chest strap and watch, is one of the best methods. Many of these watches allow you to input your exact target heart rate range, and it will beep to alert you if you are above or below those limits. Many pieces of cardiovascular equipment also have heart rate monitoring handles that you can hold onto. You can also manually take your heart rate at your wrist or neck. Place your second and third finger on your radial or carotid pulse and start counting the number of beats for 10 seconds. Multiply that number by 6.
Maximum Heart Rate
Your maximum heart rate, or MHR, is an estimation of the heart rate you could achieve during extremely intense exercise. As you get older, your MHR typically decreases. The most accurate way of determining your MHR is a stress test. Since this method is not practical for many, the simplest way to estimate your MHR is to subtract your age in years from 220. So, if you are 40 years old, your estimated maximum heart rate is 180. Keep in mind that this method is based on an estimated maximum heart rate. Your actual maximum heart rate may vary slightly from this number.
Fat Burning Zone
Your target heart rate for fat burning is approximately 55 percent to 70 percent of your maximum heart rate. Multiply your MHR by 0.55 to get your lower level threshold, and multiply your MHR by 0.70 to get your upper level threshold. So, if you are 40 years old, your lower level threshold would be 180 x 0.55 = 99 beats per minute, and your upper level threshold would be 180 x 0.70 = 126 beats per minute. This would make your fat burning zone 99 to 126 beats per minute.
Stay in The Zone
Once you have calculated your fat burning zone, be sure to adjust your intensity during exercise to stay within those upper and lower limits. Periodically check on your heart rate using one of the methods listed above. Your percentage of calories burned from fat will decrease if you go over this range.