Training yourself to burn fat for fuel – the key to endurance success (and good health).



More and more long distance runners, cyclists, triathletes etc. are coming to understand that the conventional advice for fuelling endurance effort is simply wrong. For years they have been told that carbs are the primary fuel source for going long and that anything less than a full blown pasta fest pre race or workout, followed by repeated ingestion of sugary gels, energy bars and the like are the only way to stave off ‘bonking’ (where the brain tells the muscles to shut down because there’s no more glycogen available to it). And the truth is that, if you follow the standard Western diet and are therefore, by definition, carbohydrate dependant, then you will crash without a regular sugar fix. Since this is what most people are doing, the advice actually does hold true for them because, although they have huge stores of body fat in most cases, they are totally prevented from using these for energy due to insulin being permanently stimulated to deal with the high blood sugar.

So what can you do to avoid the obviously extremely harmful effects to the body of incessant carbohydrate loading? The answer is to train your body to burn body fat for fuel, instead of sugar. The two main ways to achieve this are by eating a real food (i.e. high fat/low carb diet) diet, combined with training at your maximum aerobic heart rate for a period of time and taking care not to exceed this heart rate, which is typically around 65% of maximum. Most people will not have the patience to do this, even if they hadn’t been completely brainwashed into thinking that burning calories is the only thing to consider in all this. This science has been been out there since the 1980’s or even before, yet it’s ignored by even seasoned athletes and coaches, because more and harder just feels like you’ve had a workout.

However much the evidence is incredibly clear, the truth is that this method of training is just not sexy or marketable in these days of HIIT training and sugary snacks everywhere. The result is that most endurance athletes are repeatedly injured, catch colds, don’t get enough sleep, underperform and run out of energy, because they are essentially working against, not with, their body. Moreover, there are reasons to believe that repeated chronic cardio day after day is damaging the heart and accelerating the ageing process.

The absurd truth is that any event lasting more than a minute or two is actually relying far more on the aerobic system for energy (i.e.. with oxygen) than the anaerobic system (where you begin to labour in your breathing). Even 5k is 88% aerobic and a marathon is 99% aerobic! So why in God’s name does the average recreational athlete spend at least 50% of her time training the anaerobic system with high intensity workouts?? Elite athletes, on the other hand, spend around 80% of their training time in the aerobic zone – in other words they are working less hard than you most of the time yet getting much better results! Just maybe there’s a message there!

If you are doing most of your training in the anaerobic zone, as most regular recreational runners and triathletes are, as well as anybody engaging in HIIT sessions regularly, then you WILL crave more carbohydrates and will be repeatedly breaking down your aerobic fitness, hampering your long term development, risking injury and illness. We all love high intensity workouts because we feel like we’ve achieved something and they’re fine done now and again as part of a long term programme. However, to only do anaerobic workouts and spend the rest of your time in activity makes for a poorly trained athlete.

On the other hand, if you can master the trick of burning fat for fuel, instead of sugar, you will be rewarded by literally boundless energy (in theory you could run over 600 miles without food, just by accessing your stored body fat for fuel). You will no longer get sugar crashes where you run out of energy because the brain tells the muscles to shut down in the absence of sugar. You can literally take distance right out of the equation altogether and run all day long through this combination of training and diet.

To find out more contact David on 07504439555 or


2 thoughts on “Training yourself to burn fat for fuel – the key to endurance success (and good health).

  1. Hi David, this is really interesting and challenging to what we’ve been conventionally told to do, eating and exercise wise. I get the fat-burning theory.

    Could you please expand or write a longer piece on what you mean by spending more time in the aerobic zone, rather than the ana-aerobic state? I get your point of frustration, but I need something I can act on to make that change or clear examples of how that actually works in practice. I wouldn’t know how or what to do with %s when I’m out running 😀 Thanks!


    1. Hi Mel. Thanks for your comment. Hopefully I’ll see you at Abingdon on Friday to discuss more but the aerobic zone is where you are not in the least bit forcing your breath – you could literally go on all day assuming, sufficient muscle strength and no injuries etc. You could carry out an easy conversation at this pace. In practice, the higher end of this zone is around 65% of maximum heart rate if you’ve got an accurate monitor with chest strap. It’s around 6.5 out of 10 on a scale of perceived effort. It’s that level just before you start to accumulate lactic acid and discomfort in the muscles of any kind. At this level you are achieving maximum aerobic conditioning and building a whole load of physiological adaptations such as increased mitochondria, more efficient supply of blood to working muscles, super efficient form and economy and much much more, as well as the psychological benefits of being more in tune with your heart, breathing etc. This kind of training is best done out of season but is also very helpful from a recovery point of view in season.


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