Staying in the fat burn zone?
I was checking out some options for a new exercise bike, and was reminded of another fitness myth. This one really bothers me, because it can be responsible for wasting so much time and causing frustration for many who want to lose fat.
I’m sure you’ve all seen the alluring “fat burn” mode that accompanies almost any display on a “cardiovascular” machine.
You would think that the pervasiveness of this display mode would indicate that there is at least some evidence that this is, in fact, a mode that actually burns fat!
Well, the truth is that there is evidence that there is a fat burning zone. Unfortunately, there is a big difference between what the evidence suggests and what is conveyed to the consumer.
Some of you may have heard me reveal the truth behind the fat burn zone, but this is a resilient myth, so I will combat it once again. This time, I have even more evidence.
You see, the fat burn zone is purportedly a level of intensity where the body burns mostly fat calories as fuel, versus carbohydrate or protein. This occurs, depending on the source, at about 60-70% of your maximal heart rate while exercising.
If you actually want to take this beyond the realm of exercise, it is a fact that the body actually burns fuel mostly from fat at rest as well!
Obviously, no one would suggest that sitting around on your butt watching T.V is the most effective way to burn fat.
However, equipment manufacturers and some exercise physiologists seem to have no problem inferring that exercising at a lower intensity will burn more fat. They also ignore that there are countless of other factors at play here, but for now we’ll just focus on the fat burn zone.
One key error these folks are making is that they fail to emphasize that it is not the percentage of calories burned from fat, but rather the quantity of fat calories burned.
Here’s the an analogy to clarify. Let’s say I offer you two different stock options. First, you could have 98% ownership of Spectrum Fitness Consulting. Second, you could have 2% ownership of IBM. Which option would you choose? Obviously, you’d choose the latter because you would make more money. Although it is a smaller percentage ownership… it is a smaller percentage of a much greater number.
Similarly, even if you are burning a greater percentage of calories working at a lower intensity, you will still burn more calories working at a higher intensity. So, although a smaller percentage of calories will be burned from fat at a higher intensity, it is a smaller percentage of a much greater number, thus you will still be burning more fat calories.
This really is just common sense – working harder will help you burn more fat. It is amazing what marketing hype can do to distort our thinking.
Let’s look at some specific research on this. Dr John Porcari from University of Wisconsin at Lacrosse performed a study in which one group exercised in the fat burn zone. They burned 240 calories, 44% from fat, amounting to 108 calories from fat. Another group exercised at higher intensities, and burned 450 calories, 24 % from fat, amounting to burning 120 calories from fat.
But even this evidence does not do justice to the significance of working out at higher intensities for fat loss. We can not judge the effectiveness of fat loss exercise based on only how many calories were burned during exercise. Rather, we need to also look at how many calories are burned while we are not exercising – as a consequence of exercise. This is a proven benefit of resistance training and interval training, for which multiple studies support their superiority for fat loss training versus exercising in the “fat loss zone”.
This doesn’t mean that moderate intensity exercise is worthless. In fact, I recommend it for some clients. But for most it certainly cannot make up the majority of your program if you are serious about improving your health and burning fat.
Hopefully this myth is laid to rest now.
Dedicated to your health,