Does Trail Running Burn Fat Or Muscle?

It seems like a simple question to answer, but I’m aware that it gets asked a lot. I’m not sure what people’s preoccupation with burning fat over burning muscle is, but here’s my take on it.

Do We Burn Fat Or Muscle First When Trail Running?

Does Your Body Burn Fat Or Muscle First When Fasting - Fat or Muscle

Does trail running burn fat or muscle first? I love to Trail Run, as you probably already know it you’ve been on this blog before. It is probably my favourite outdoor pastime. I’ve been doing quite a bit of it in the last month, and I’ve lost some weight and look better, but I was wondering if I am going to lose too much muscle mass rather than just burn lots of fat, which would be my preference. So I thought I’d look a bit deeper to find out. Here’s what I found.

Which Do We Burn First when Trail Running, Fat or Muscle?

You’ll probably be pleased to hear that the answer is that we burn Fat before muscle when we are trail running. We always burn Fat over Muscle when we go for a trail run.

Does Trail Running Burn Fat Or Muscle - Intense Exercise

When we put the rigorous demands of Trail Running on our bodies, first our bodies will burn off off any available Carbs in the form of Glycogen in our Muscles and Liver, then it will turn to the Fatty Acids in out Blood Stream and once they are used up, we will switch to burning the Stored Fat deposits. Only after these three energy sources are depleted will our body begin to burn off any Muscle. This scenario is very unlikely in the average and even in the advanced trail runner.

Will I Build or Lose Muscle Trail Running?

Trail Running is unlikely to either build muscle or lose muscle in any significant amount. It will certainly tone up the muscles that you already have making you look slimmer and more defined.

As we discussed earlier you are unlikely to burn any muscle off until you have depleted absolutely all of your energy sources, including all of your stored fat deposits. So unless you are undertaking an epic Trail Run, something on a par with the Marathon des Sables, you aren’t going to burn off your muscle.

Does Trail Running Burn Fat Or Muscle - Marathon Des Sables

Marathon des Sables, or MdS, is a six-day, 251 km ultramarathon, which is approximately the distance of six regular marathons. The longest single stage is 91 km long. This multiday race is held every year in southern Morocco, in the Sahara Desert. It has been regarded as the toughest foot race on Earth.


When it comes to the process of building muscle, Trail Running would be a very inefficient way to do this. To build muscle effectively we need to put a lot of resistance on our muscles, such as lifting a very heavy weight and do it only a few times. This is the method that classic Body Building uses, and as you can see the results can be quite astonishing, but you won’t get a body like by trail running, no matter how hard and how far you run.

Does Trail Running Burn Fat Or Muscle - Building Muscle

With Trail Running we are putting high, low and medium resistances on our bodies and switching between them as our speed and the terrain changes for multiple repetitions. This is not an effective way to build muscle, but it is a great way to tone it.

Is There a Link between Trail Running and Muscle Loss?

Does Trail Running Burn Fat Or Muscle - Losing Muscle

Studies show that trail running is detrimental to muscle building but also not conducive to muscle loss. Therefore there appears to be no link between trail running and muscle loss.

Muscle loss is usually caused by lack of use, or by being used for fuel in a “Starvation Response” where our body seeks another source of fuel by breaking down muscle protein into energy. Neither of these are going to happen when you are on a trail run.

Does Trail Running Burn Fat Effectively?

Yes, Trail running is an extremely effective way to burn fat. When we trail run it is reported to be at least 10% more efficient at burning body fat then road running due to the high demands of the terrain and the challenges we put our bodies through.

The high demands presented by the challenging conditions will burn through our available Carbs and into our Fatty Acids faster than most other forms of exercise. This is exactly what we need when we are fat burning.

We can increase the rate at which we are burning calories, so therefore fat burning by increasing the intensity of our trail run, running up steeper inclines, carrying extra weight or doing longer trail runs.

Where will I lose Fat from First when Trail Running?

Does Trail Running Burn Fat Or Muscle - Cannot Target Fat Burning

It is impossible to say. Spot targeting fat loss has been like the quest for the holy grail in the weight loss and fat burning world, unfortunately, so far it has been found to be impossible.

You cannot target where you will lose fat from first. It is most likely that the place where you store far the most easily, will be the most difficult area to lose it from.

However, you will be burning some fat from all of your bodies fat deposits if you are trail running with enough intensity and for long enough, you will be burning fat from everywhere, and lots of it.

Is Trail Running better than Road Running for Fat Burning?

Does Trail Running Burn Fat Or Muscle - Trail Running vs Road Running

Studies show that Trail Running is definitely better for burning calories, so therefore better for Fat Burning than Road Running is. Trail Running is around 10% more effective than Road Running on average.

When we trail run we are constantly coming across obstacles such as puddles, rivers, muddy ground and rocks, as well as encountering rapid changes in elevation that we wouldn’t normally come across on a road run, and we certainly won’t ever encounter similar challenges on even the most sophisticated tread mill.

It is these seemingly minor differences that knock us off balance, make us stop and start, speed up and slow down and clamber over things that put the extra energy demands on our bodies and therefore in the long run force us to burn more fat.

Is Trail Running Good for your Body?

Does Trail Running Burn Fat Or Muscle - Trail Running is Good For Joints

I have friends that often mention to me that they feel that trail running is far harder on their body than road running. However, I have a different view on the subject.

Firstly I feel that your joints pounding rhythmically on a tarmac or concrete road surface must be tougher on the body and especially on your lower limb joints that treading on tracks, grass and mud.

Secondly, I feel that you will put your joints through a far greater range of movement when you trail run, surely allowing the whole joint to be put through it’s paces, lubricated and strengthened.

Thirdly, the harsh terrain that you are going to encounter is going to tone up your body, strengthen your muscles, allow you to build a strong core and exercise your cardiovascular system thoroughly, with the added benefit of improving it’s efficiency for next time.