..............IBIZA PERSONAL TRAINER - HEALTH & FITNESS ARTICLES
.......................... ..........MYTH-BUSTING - THE FAT-BURNING ZONE
.......................................................- Kev Grant
............................................www.ibizapersonaltrainer.com
In this, the first article of the Myth-Busting series I will address one of the more common myths that still seems to be in circulation, and that I come across on an almost daily basis, it’s an old favourite that still circulates through the Health and Leisure Industry…
The Fat Burning Zone
This myth seems to have become so widely accepted as fact that even some “Fitness Professionals” still perpetuate this on occasion, and there are still companies charging good amounts of customer’s hard-earned money to do all sorts of high-end technology tests, VO2max etc, and then send their customer away with what is basically untrue advice, i.e. exercise at lower Heart Rates and you will burn off more fat.
This very common misconception is based on the fact that the bodies’ energy systems use different fuels depending on what level of output is required of it. At lower intensity exercise levels (and hence Heart Rates) the body will use on the aerobic energy system, which it is true will use a higher percentage of fat than carbohydrates, along with oxygen to produce the required energy than at higher Heart Rates, where the body will utilise proportionally more carbohydrates.
However the point that believers of this particular fable miss, is that even though it is true that a larger percentage of fat will be used at lower HR s, at higher work rates, the total amount of energy used will be proportionally higher, so that even a smaller percentage of the higher total, will be usually more than the higher percentage of the smaller total.
This is illustrated in the figures below, which although slightly simplified, represent 30 minutes worth of exercise by a 70kg individual, at first moderate intensity, and then at high, or vigorous intensity.
Exercise Intensity Level ............... Moderate Intensity .............High Intensity
................................................(60% max heart rate) ........(80% max heart rate)
Total calories burned: .......................... 190 ...................................300
Percentage fat calories burned: ..............75% ..................................50%
Total fat calories burned: ......................142 ...................................150
It should also be noted that as well as burning more calories from fat, the calories burnt which are comprised of carbohydrates also have to be factored into your overall energy balance equation. After all, even if the energy comes from glycogen stores in the body, this still has to be replaced by food eaten, or by the body’s fat reserves at some later point in time, should you not eat enough to do this.
And the last nail in the coffin of “The Fat Burning Zone Myth” is that it has been shown that high intensity exercise will also raise the bodies’ metabolism significantly for several hours afterwards, giving you an “afterburning” effect, and continue burning more calories than usual, even whilst at rest.
In conclusion, if you are looking to affect your Energy Balance Equation using exercise, i.e. in a weight management context, then assuming you are able to safely, you should aim to be exercising in your 75-85% Max HR zone. If you are a beginner and not yet fit enough to sustain that level, then adding some intervals of higher intensity into a lower intensity workout is a good interim approach, building to the higher levels of intensity.
.................Kev Grant is a REPS3 Qualified Personal Trainer based in Ibiza
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