The concept of a fat-burning zone is a myth. Your body takes energy from fat and carbohydrates in different percentages. When at rest, your body takes all of its energy from fat, so your fat-burning zone would be when you're vegged out in your reclining chair. The true fat-burning zone, however, is really your target heart rate zone, which is a range of beats per minute that burns an optimal number of calories for fat loss without overtaxing your body. Exercise in this zone three to five days a week for 20 to 60 minutes to see a reduction in body fat, recommends "NASM Essentials of Personal Fitness Training: Course Manual."
There are two formulas for calculating this zone. One is simpler and requires only a calculator. The second method is called the Karvonen formula. It is more accurate, but you must first determine your resting heart rate.
Easy Method
Step 1
Subtract your age from 220 to get your maximum heart rate, which is the average heart rate of a baby at birth. The theory is that for every year you are alive, your heart rate slows so that the maximum amount of times your heart should ever beat per minute decrease by one, according to an article entitled "Fitness: Tests That Measure Up" at MontrealGazette.com. For example, a 60-year-old would have a max heart rate of 160 bpm (beats per minute).
Step 2
Multiply your max heart rate by the lower end of your desired training zone percentages. Most people should ideally exercise at a zone of 60 to 75 percent of their max heart rate. Seniors or de-conditioned individuals may wish to start lower, such as at 50 percent, recommends "NASM Essentials of Personal Fitness Training: Course Manual." Athletes may wish to train higher with proper conditioning. For example, a person with a 160 bpm max heart rate would have the lower end of his target heart rate (THR) zone at 96 bpm.
Step 3
Multiply your max heart rate by the higher end of your desired training zone, which will likely be 75 percent. The person in the above example would have the higher end of his zone at 120 bpm, making his ideal zone for fat reduction 96 to 120 bpm.
Karvonen Formula
Step 1
Determine your resting heart rate (RHR). Allow yourself to wake up naturally from a night's sleep or a nap. Alarms or loud noises will increase your heart rate. Take your pulse using a heart rate monitor watch or manually with your fingers immediately upon waking. Do not sit or stand up first. Use a clock with a second hand or a stopwatch to take your pulse for 15 seconds and then multiply by four. For example, if you counted 20 beats in 15 seconds, your RHR would be 80 bpm. Write down your RHR.
Step 2
Subtract your age from 220 bpm to get your max heart rate. For example, if you are 40 years old, you would have a max heart rate of 180 bpm. Subtract your RHR from your max heart rate. For example, a 40-year-old with a RHR of 80 bpm would subtract 80 from 180 to get 100 bpm.
Step 3
Multiply the sum of step 2 by 60 and 75 percent, which is 0.60 and 0.75. In the example above, this would be 60 and 75 bpm.
Step 4
Add your RHR to the sums from step 3 to get your THR zone. In the example, the THR zone would be 140 to 155 bpm.
Tips and Warnings
- Lie down for a minimum of 10 minutes in a relaxing environment and then take your heart rate for an approximate RHR if it is not feasible to take your heart rate upon waking.
Things You'll Need
- Calculator
- Stopwatch
References
- "NASM Essentials of Personal Fitness Training: Course Manual;" Micheal Clark, Scott Lucett, Rodney Corn; 2008
- "Montreal Gazette": Fitness Tests That Measure Up
Member Comments