FAT BURN ZONES, HEART RATES, and SWEAT...

An interesting point was brought up to me today that I wanted to address in this blog:

A classmate was comparing the calories she burned after a given workout with the calories another classmate burned (they both had Polar watches that monitor calories burned and heart rate) and found that, although they did the same exact workout, she had burned a significantly less amount than her classmate.

How could this be? Other than the obvious fact that people are inherently different and will exercise differently and burn calories at a different rate, there was an interesting tidbit than must be touched upon. The classmate that burned more calories had performed a pre-class workout (of about 20 minutes) whereby her heart-rate was already elevated before she got to class. The classmate that burned less calories had arrived to class without a specific warm-up. By beginning her workout at an elevated heart rate she was either in her "fat-burn zone" or very near, thus making her entire class-time more efficient for fat-burning and calorie-burning.

There are a couple of points I want to make on this topic. I will be brief as I've addressed the "fat-burn zone" in earlier posts but I want to re-address because this is a salient issue, what with the RBS Challenge and all.

What is the "fat-burning zone"? Briefly put, the fat-burning zone is a specific heart rate range (different for each individual) where the human body will utilize fat as a fuel source before anything else (carbohydrates). The one thing to remember is that the human body wants to use fat as fuel--it is more efficient, yields more energy, and far more effective in low-to-moderate stress situations. That is why we store fat--we don't store carbs and proteins (specifically). The "better shape" a person is in the more efficiently they will be able to metabolize (use) fat over other fuel sources. When stress and exercise increase past a certain point (called the Anabolic Threshold) the body will "switch gears" and begin utilizing carbs and ultimately protein (muscle).

There are 2 basic ways to determine one's fat-burning zone. One is to do the METabolic Test (some of you have done this) where you undergo a Stress Test with a mask and a machine that monitors heart rate, oxygen inspiration, carbon dioxide expiration, etc. This test costs money but is much more specific and accurate.

A less accurate way (but still a decent guestimate) is to utilize a simple formula: 220 - your age = your max heart rate. Your fat burn zone will be about 70-80% of your max heart rate. So, if you are 40 years old, 220 - 40 = 180. 180 * .8 and .7 = 126-144 beats/minute heart rate for fat-burn zone.

I encourage 2 things with this information. Find your fat burn zone in one way, shape or form. If you can, warm-up prior to any exercise and get your heart rate to that zone. A phenomenon always occurs in that your body's heart-rate and temperature will remain elevated throughout the exercise, thus burning more calories and ultimately fat.

As always, medications, monthly cycles (i.e. menopause or ovulation), and other factors can construe this information one way or another. Please see for more information or with help to find your fat burn zone.

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