Do you really have to stay in the fat burning zone to lose weight? Many people believe you do. However, this is just a misconception. As long as you are burning more calories than you are taking in, you will lose weight.
The fat burning zone is the target heart rate range that is recommended you stay within in order to burn more fat calories. Most charts show the range to be 60-70% of your age-predicted maximum heart rate (APMHR). Your APMHR can be calculated by subtracting your age from 220. You would then multiply this number by .60 and .70 to get your fat burning zone range. Although, it is true that you can burn a higher percentage of fat calories when exercising in this zone, losing weight is not based solely on how many fat calories you burn. It’s based on total calories. For those concerned with burning the most total and fat calories, you can actually do this by increasing your intensity level. This means exercising in a heart rate range above the fat burning zone. Even though at higher intensities, the percentage of fat calories burned is lower, the actual total fat calories burned is higher. Remember, the ratio of workout intensity and its correlation to burning calories varies from individual to individual.
Let’s put this is the form of a simple math problem. Joe and Bill both exercise for 30 minutes. Joe is only working at 50% of his maximum heart rate, while Bill is working at 75%. Who burns the most fat calories and who burns the most total calories? The numbers used here are for this example only, individual results will vary. Let’s say Joe is burning 7 calories per minute of which 90% are fat calories and Bill is burning 14 calories per minute of which 60% are fat calories. So at the end of 30 minutes, Joe has burned 210 total calories and Bill has burned 420. Joe has only burned 189 fat calories, but Bill has burned 252 fat calories. Although the percentage of fat calories being burned by Joe is higher, the actual total fat calories he’s burning is lower. Bill is not only burning the most calories, he is also burning the most fat calories. It would benefit Joe to increase his intensity levels. Not only will this help him burn more calories, thus helping in his weight loss efforts, but he will also improve his aerobic exercise performance. If you’re going to exercise, why not get the most benefit from it. The bottom line is when trying to lose weight, your cardio exercise should be “as hard as you can for as long as you can”.
Of course, you may need to check with a doctor before starting any exercise program. There could be valid medical concerns that prevent you from working at higher intensity levels. The American Heart Association’s website has a PHYSICAL ACTIVITY READINESS QUESTIONNAIRE that may be helpful.
Sources: NSCA’s Essentials of Personal Training Copyright 2004 p. 403, International Fitness Association’s Heart Rate Chart at www.zazzle.com/ifa_heart_rate_chart_poster-228622695006173119 , and
The American Heart Association at www.americanheart.org/downloadable/heart/1176844249407Phys%20Activity%20Questionnaire.pdf