365 Ways #26–The “fat burning zone” fallacy Posted on August 16, 2010, 0 Comments

#26–Cardio manufacturers have popularized the idea that working out at a specific level will allow the body to burn more fat. And in our fat-phobic society, this belief has led to a gym industry which caters to cardio. Walk into any fitness facility in the U.S. and you’ll see thousands of dollars worth of treadmills, ellipticals, stairmasters, and bikes. Attached to each will be a sign up list to keep the waiting masses in order until they can enter “the fat burning zone”.

And while it may be true that exercising in this zone utilizes a greater percentage of calories from fat, the numbers can be misleading. Let’s take a 150lb male who, when running at 6mph, is comfortably in the famous fat burning zone. Burning approximately 600 calories during the course of his workout, his contribution from fat will be around 50% or 300 calories. Now take this same guy and have him run 8mph. He burns approximately 800 calories, but only 40% came from fat. Yet, 40% of 800 is 320. The total contribution from his fat stores is actually higher despite working above the so-called fat burning zone. And he's burning more total calories!

Additionally, the calories expended after cessation of exercise, referred to as “excess post-exercise oxygen consumption” or EPOC will keep his metabolism well above its normal resting rate for minutes or even hours after his run is finished. After all, it requires energy to remove lactate, replenish oxygen stores, resynthesize the ATP-PC system, and to bring the body’s systems back to pre-exercise levels in general.

And while all of the above factors can be affected not only by the duration and intensity of the exercise but also by gender, training status, and even timing of the exercise session, one truth is without debate: when measured strictly by percentage of contribution, the best fat burning activity is simply going to sleep. And that’s one thing the cardio manufacturers can’t sell you. No, the drug companies have exclusive rights to that…