The Fat Burning Zone – A Big Fat Myth? January 30, 2012


OK, so you may have decided that as part of your triathlon ambitions for this year that you would like to loose a bit of your body fat so become more streamlined and increase your muscle tone.  Many people believe the best way to lose body fat is to get on the treadmill or cross trainer and work in the ‘fat burning zone’, with so much conflicting advice around, this blog attempts to give you a bit of insight into this popular assumption.

The ‘fat burning zone’ was first popularised in the early 90’s when it was perceived that training within 55 to 65% of maximum heart rate will optimise calorie loss. Above 65% you will be also be burning carbohydrate but you will still continue to burn fat. Let me see if I can explain more simply by the following diagram:

As the intensity increases, the percentage of fat used for energy production decreases (and the utilisation of carbohydrates increase). So, although we utilise a higher percentage of fat at lower levels, it is a higher percentage of a lower number of calories

(A) Low intensity effort        200 cals         (Burning 60% fat)=60% of 200 = 120 cals of fat

(B) Higher Intensity             400 cals         (Burning 40% fat)=40% of 400 = 160 cals of fat

It is therefore far more beneficial to work in the heart rate range of 65 to 80%, plus you will be increasing stamina and strengthening your cardio vascular system.  (We will discuss heart rate and how it can be used at a later date). The other benefit of working at a higher heart rate is the ‘after burn’ of calories once exercise is completed lasts for longer.

Another belief with gym users is that muscle weighs more than fat. Think about this question; What weighs more 20 lbs of feathers or a 20 lbs of steel?    Muscle does not weight more than fat but it takes up less volume than fat. In other words 5 lbs of muscle is denser and actually looks smaller than 5 lbs of fat, therefore toning and shaping your body. However the really great news about muscle is that it is more metabolically active than fat, so the greater muscle density you have the greater number of calories you will burn.   By bringing more resistance work (with weights) into your routine will help turn your body into a fat burning machine!

Some brief guidelines when doing resistance work

  • Each set should be completed to form failure.
  • The rep range needs to be appropriate to your goal.
  • The rest needs to be appropriate to your rep range.
  • Ensure the correct technique at all times

How can we use this information to help with our training programme?

  • Ensure that you are training in the heart rate zone to get the maximum benefit from a fat burning, circulatory and respiratory system point of view.
  • To lose body fat don’t just do CV work; also do resistance work to increase muscle mass and hence increase your metabolic rate which in turn burns more calories when you are not even exercising.   For every pound of lean muscle tissue you acquire you will burn an additional 50 – 100 calories a day even when resting.

If there is a particular subject you would liked covered in future blogs, please let me know.

For more information about training for triathlon please visit my website at

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Written by Steve Lloyd

Steve Lloyd

British Triathlon Federation Level 3 Performance Coach

Named as Britain’s ‘most motivating Tri Coach’ by Triathlon Plus magazine, Steve Lloyd is an extensively experienced Triathlon Coach and age-group Triathlete.
He has coached numerous athletes over the last 8 years across all distances working with complete beginners through to elite triathletes.

Recognised by the British Triathlon Federation in 2011 as their Performance Coach of the Year Steve continues to work with athletes at a high level both in his role as the West Midlands Regional Head Coach and through his business Absolute Tri. He is also is seen as an industry expert and is regularly called upon by the media for comment.

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One Comments
Rejay June 7th, 2012

I am not a coach but practice makes peerfct. You should improve a lot with front crawl as your breathing becomes more natural. I think this is the key to alowing your body to relax which in turn improves streamlining and makes the stroke more economical. If you are doing triathon then I suppose you will wear a wetsuit.This wil help buoyancy. probably a silly thing to say as you are probably already doing it, but train in your wetsuit Your legs shouldnt be overworked and they should get a bit of a rest for the other parts of the triathon especially with a wetsuit I said I am not a coach but I think this is pretty straightforward but also useful and practical advice.