Does faster running burn more fat?

Me picking the pace up in the park

Towards the end of the article James says that he has noticed that leaner runners are faster runners but this could be a little bit like the chicken and the egg. Which comes first? If you are leaner to begin with does that mean that you are going to be a faster runner or is it, as James believes, that you will become lean if you run faster training sessions?

There is a lot to think about here and I'm sure we can all think of runners we know who are lean and slow, lean and fast, heavy and slow, heavy and fast but it did make me think of a time when I was once asked "how do you eat so much and stay so slim?" I was taken aback at the question, not because I didn't think I ate 'so much' or was 'so slim' but because for a long time I had been wondering how the guy asking the question, Pete, ran so much and stayed so fat. Without realising what I was saying I actually replied "How do you run so much and stay so fat?" Luckily he was amused by this and so no offence was taken!

At that time I was training hard. I was putting in a fair bit of volume and I was also doing my speed work. I was probably doing three out of ten sessions per week of high intensity work. Whenever I saw Pete he would be trundling along at a pace that was only a wee bit quicker than a walk but, was I able to pick up the pace because I was quite light and was he unable to pick up the pace because he was so heavy or had my training reduced my weight and had the lack of intensity in his training sessions meant that he couldn't shift the weight?

Well I suppose I'm lucky in that I've always been fairly lean and light but then I've always been very active. I'm not sure if I'm light because I'm active or that I'm active because I'm light. People say I take after my dad and he's in the skinny brigade too.

So, if you want to lose weight, how should you train? Should you go out for those long slow distances or should you concentrate on quality and not quantity?

James states that numerous research studies and exercise physiology texts agree that the human body primarily uses fat stores as a source of fuel at moderate intensities — say, running at 6 mph with a heart rate at 65% — and switches to using stored carbohydrates as a source of fuel as exercise intensity climbs until, at the highest intensities, more than 90% of the energy required comes from those carbohydrate stores.

So that's it then? Surely? If a runner wants to burn fat they should train at a moderate intensity, at 65% of maximum heart rate and barely get out of breath? Apparently not. James makes a strong case for calorific deficit. He reminds us that sustaining higher intensity exercise burns more calories. Therefore — dietary intake being equal — exercising at higher intensities is going to allow you to generate larger caloric deficits, leading to additional weight loss.

He says "if you're in a caloric deficit over time, the type of energy stores — fat or carb — you're using during exercise is irrelevant. Your body is going to engage in fat-burning whether you are exercising or not. You could be sleeping, doing your taxes or watching videos of honey badgers on YouTube and fat is still going to burn."

One of the best things about running at a higher intensity is the after burn or Excess Post Oxygen Consumption (EPOC). Basically you continue to burn calories as your body comes back to normal after being revved up by an intense training session so, if nothing else, it means you can spend less time training and more time burning calories if you train that little bit harder.

It also seems evident that shorter, faster training sessions are better for us than the long slow stuff when it comes to protecting ourselves from heart disease, this is according to a research project that monitored 5000 people in Copenhagen who cycled regularly for 20 years. We put this news story on our website last week. The study was based on people with health problems such as diabetes or high blood pressure. It would be interesting to know if weight or body composition was a factor in it.