Running for weight loss
Sport

Running for weight loss

You’ve finally decided to run! You’re sick of feeling guilty after having spent the whole night eating crisps in front of the TV! Now you want to be like those people who lose weight by running and look so fit!white

So you go on the internet to look for some advice and try to know the best way to run for weight loss. What is the best intensity? The best length? You’re lost, nobody advises the same thing.

 

Energy sources during exercise… Time for a bit of theory!

Your muscles need ATP to work. Only a small amount of ATP is stored and is directly available in muscles. Creatinine is another source of energy directly available in muscle cells. Once these stores are used up after only a matter of seconds, your body uses two main sources of energy:

  • Carbohydrates, stored as glycogen in the liver and in the muscles
  • Fat, stored as triglycerides in your muscles and adipose tissue.

In order to burn fat, you have to use as many triglycerides as possible. So how should you run to make your metabolism use mostly fat as an energy source

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How to optimize fat burning in practice?

There are two opposite points of views on the subject.white

Let’s talk about those who advocate longer runs of medium intensity [1]

The proportion of carbohydrate and fat your organism uses is unbalanced. According to studies, it is during moderate intensity exercise that your body uses the most fat. It takes longer for the body to convert fat into energy than carbohydrate into energy. Your body would also use more fats during long exercices.

So long runs of moderate intensity would be more efficient to lose weight. But the way you use your fat doesn’t only depend on the length and the intensity of your run, it also depends on your training and varies a lot from one individual to another [2].

According to these scientific knowledges, one part of sport trainers advise people wishing to lose weight to run regularly for at least 40 minutes. You need to do a long effort so that your body has time to burn fat. But for the same length, you will burn more fat if you run fast than slow… so it’s difficult to find the perfect rhythm…

runner running fat loss

And now, let’s try to understand why others advise the opposite, “to lose weight, thirty minutes of sport are better than one hour”.

This was shown in a danish study made on 60 moderately overweight people for 13 weeks[4]. Half of them did 30 minutes of sport per day whereas the others did one hour. What were the results? There was no significant difference in weight loss between the two groups. It seems strange but the explanation could be the state of mind of the participants: those who only exercised 30 minutes kept more motivation during the rest of the day so they managed to have a healthier lifestyle. Whereas those who exercised 1 hour felt too tired to do so. Can we generalize this study? Motivation is person dependant, isn’t it?

Some also question the fact that it is best to do moderate intensity running. Recent studies revealed the efficiency of activities such as cross training and Crossfit to lose weight, they are intense but short activities[3]. Indeed, there appears to be a strong correlation between the intensity of the activity and the way your body burns fat. Something interesting is that your body continues to burn fat afterwards, it is called the “afterburn effect[5]. This effect is greater after an intense activity like crossfit. But it is difficult to find reliable information on the extent of the afterburn effect: depending on the source, it supposedly represents between 7 and 95% of total energy expenditure of the physical activity[6]

 

So all in all, what is the best way of running to lose weight?

You will have noticed that it is really difficult to know which piece of advice is the best amongst everything you can read on the internet! The scientific studies’ results are contradictory, because studies are done on different people, with different metabolisms, in different contexts. All in all, what’s the best way to run for weight loss? There is no universal answer because it depends on you, on your motivation and on your metabolism!

How about you? What is working for you?

 

 

References:

[1] : http://www.pponline.co.uk/encyc/fat-burning-using-body-fat-instead-of-carbohydrates-as-fuel-40844

[2] : http://www.courir-plus-loin.com/aliments-et-substrats-energetiques-quelle-energie-pour-courir/

[3] : http://ajpregu.physiology.org/content/early/2012/07/30/ajpregu.00141.2012

[4] : http://www.nature.com/ijo/journal/v32/n4/full/0803781a.html 

[5] : https://www.researchgate.net/publication/9025532_Effect_of_Exercise_Intensity_Duration_and_Mode_on_Post-Exercise_Oxygen_Consumption

[6] : http://paléo-fit.fr/afterburn-effect-bruler-gras/