Calculating fat burning rate is simple. There are few different ways to calculate, but they all eventually give almost same result. I will use Karvonen Formula to explain fat burning rate or fat burning zone calculation. In case you don't know what is fat burning rate, let me write a few lines on this, beofre I calculate it.
What is Fat Burning Rate or Fat Burning Zone
When you burn calories at low intencity exercises, like walking, you burn mainly fat, not carbohydrate. When you choose to work at high intesity workout, like running fast, you burn mainly carbohydrate. Though during high intentisy workout you burn more calories, still you may like low intensity workout, since it burns directly from fat. Now how to define low intensity workout. When you walk, if your heartbeat is within a certain range, suppose from 112 beat per minute to 120 beat per minute ( it will be different for different individuals, and calculting these two values specifically for you is the goal of this page) it will be called low intensity exercise. Since at this heart beat zone you body burns mainly fat, it is known as fat burning zone. If you walk faster, you will reach higher intensity exercise, since your heart beat will be higher than that is specified in fat burning zone. So when your heart beat cross the fat burning zone it reaches cardio zone.
When your heart beat is in between 55% and 65% of your maximum heart beat rate, you are in fat burning zone. When it is more then 75%, you are in cardio zone. At far burning zone you will spend calories directly from fat, while at cardio zone you will spend calories directly from carbohydrate. Ok I think we covered enough, now let's try to calculate fat burning zone heart beats. If you don't like math, go to the bottom of the page, where I calculated it in a simple way, but still close to the actual value.
Calculating Fat burning zone
First find out your resting heart rate. When you are in a normal condition, meaning not tired or in tension, take your pulse rate for one minute, it will be your resting heart rate. Usually it should be something around 65.
Now calculate your maximum heart rate. There is a simple way to calculate it, 220- age, so if you are 35 years of old, your maximum heart rate (MHR) is 220 - 35, or 185. But if you don't hate math, then we can calculate it more accurately as 206.9 - (0.67 x 35 ), here 35 is your age, (if you are 40 you should use 206.9 - (0.67 x 40) ). So 206.9 - 0.67 x 35 = 183. See it is very close to the simple formula of 220-35, which was 185.
Now deduct your resting heart rate, which was 65, from MHR, so it should be (183- 65) 118. Find out 55% and 65% of these value, which are 65 (118 x 0.55) and 77 (118 x 0.65). Now add back that resting heart rate, so it becomes 65+65 = 130 and 65+77= 142.
So finally your fat burn zone heart rate is from 130 to 142. Don't forget, it is not actually your fat burning zone, I calculated these values using tentatively your age as 35 and your resting heart rate as 65. You should using actual resting heart rate and age and recalculate the whole process.
What if you hate math !!
Ok I have a very easy process for you, you will get very close to the result above, but in a very simple way. Ready .
Your age - 35, Resting Heart rate -65.
Lower fat burn zone value -- (220 -35)x 0.55 =102, add 30, so it is 135
Upper fat burn zone value -- (220 -35)x 0.65 =120, add 20, so it is 140.
Very close right !
Try to be within 55% to 65%, if you are not that fit. Once you become strong and very fit, your fat burning zone will be higher,so you may choose 85%.