Kerry Ultra

Running for 17hrs on Almost Nothing



If there is something in nature you don’t understand, chances are it works in a far more sophisticated way than we thought.

This sums up us homosapiens.

Yet today, we think we know how everything works, we do the studies, we prove this that and the other.

So I’ve stopped trying to claim I know how everything works, I don’t. Instead I just do…. As I have realised that those who talk just talk and those that do, learn.

Picture this… a small town in the north of Italy, surrounded by rocky peaks, the Dolomites. Around which, is an ultra mountain marathon course, 119km long with 6,500m of climbing. The winner completes it in about 13hrs with the last person over the line in 30hrs.

You would think this requires a huge amount of “fuelling” and a constant intake of carbohydrates to keep you going.  That’s what all the studies say, so we must do it.

Here’s what I did:

The days leading up to it involved my flying over to Italy, then driving north up to the race location. I use travelling as a chance to fast. Airport food is crap and aeroplane food is worse. So I use what I know helps me i.e. not eating. This allows me to avoid poor quality food while also allowing me to push the fat adaptation switches and even autophagy switches. This time, ate at 1pm… then travelled and didn’t eat again until the next day, after a run, at midday. So almost 24hrs of fasting and I felt good.

An early departure the day before the race meant no breakfast and a 4hr drive. So ate just lunch and dinner that day. Just two meals the day before a 119km race when we are supposed to be “loading”. The following day was race day, and with an 11pm start, this meant the whole day was for “fuelling”.

Here’s what I had

Breakfast: Eggs and pancetta

Lunch: Sausage and polenta with veg

Dinner: mackerel salad, then prosciutto and cheese.

No snacks. No juices, no fruits, no packets of biscuits, no pasta and no rice. In fact, very little carbohydrates, the so c called fuel we all need to exercise.

11pm came around and I ran. I ran for almost 4hrs without even thinking about food. I skipped the first checkpoint and ran through as I had enough water.

For the next 13hrs, I ran, hiked up and ran down some of the biggest mountains in Italy. I never felt really hungry. I was stopping at checkpoints mainly for water and a swig of electrolytes. I ate very little, just a few pieces of cheese and little samples of crostata.

I had in my backpack – 1 x packet of salted cashews, 2 x small bounty bars and 1 x banana and 1 x little pouch of honey.

I finished the race with everything untouched except the banana and 1 x small bounty bar.

I arrived in 79th position out of 1650 starters.

Okay, I didn’t win, but I felt good and finished almost in the top 5% of the field. I also wasn’t “racing” as it was my first time and also a reunion with Italian friends, so the mindset was more about enjoyment.

Getting back to the figures

Roughly, I consumed:

–          100g CHO

–          ~ 500-700Kcal

Roughly, I expended:

–          8,500Kcal – 11,500

So I ran for 17hrs, burning 8,000-10,00Kcal, but consumed only ~600kcal. I didn’t do this to make a point. I simply didn’t feel hungry and only consumed what I “felt” I needed. How did I do that?

Fat Adaptation

Very simply, and what I have been researching myself and practising for years, is increasing the body’s ability to burn fat during exercise. I’ve written about this extensively before here: and here .

I’ll just outline the simple numbers for now

10% Body Fat and 70Kg = 7,000g Fat = 69,000kcal

If you have 69,000kcal to burn, that’s more than enough for most ultra endurance events.

The myth of fuelling during:

I used to follow this 60-90g/CHO for competition. Its baloney. Before I even get into the science, I bet anyone reading this that has competed in any endurance race, and performed well, probably has been nowhere near that amount.

If you are fat adapted, and you are competing in an event like ironman, marathon, ultrarunning, cycling …. Then you can provide the ATP (energy) required through the oxidation of fatty acids in the mitochondria.

But you’ll say “but during the Tour de France, they take gels and even cans of coke”

Okay, there is one big reason that has been overlooked as to why they do this:

The Central Governor

The brain fuels primarily on glucose. During times of glucose scarcity or fasting, the liver can produce another fuel source for the brain called Ketones.

During a race, particularly a stressful race like the TdF, the brain is going to burn glucose quickly. If the other fuel source Ketones cannot be manufactured/supplied to the brain quickly enough, the brain is going into a fuel deficit.

What happens when the command centre goes low on fuel? It sends out signals to the rest of the body that it needs to conserve energy and slow down. Or sometimes, bonk. So the key during races is to prevent these fuel deficits and the easiest/most practical way to do this, is to eat something sugary.

A swig of coke, half a gel, a handful of sweets…. That’s all most of these pro cyclists or Ironman consume every now and again.  You’ll see a cyclist in the last hour, before a climb, tear at a gel, suck down half and throw the rest away. He rides hard for 1hr and wins the race. He consumed 15g of carbohydrate from the gel. Was it these 15g that fuelled the muscle to provide the energy he needed??? 60mins at 3g/min CHO.. That’s 180g of CHO needed, apparently. I’ll let you decide.

Hence, during exercise, we do not need to fuel the muscle, we need to simply fuel the brain.

The other aspect of simple sugars for the brain during exercise is the stimulation of reward or pleasure centres. Studies using carbohydrate drinks as a mouth rinse have shown improved performance. What’s happening here is that there are receptors in the mouth (and gut) for carbohydrates that trigger the pleasure/reward centres in the brain. This helps reduce perception of perceived exertion and gives you the “feel good” factor which is desperately needed during times of racing and suffering during an event.

Fear Factor

There is one other major reason why people think they need to constantly stuff themselves with foods/drink during races. It’s called fear. People are afraid. Its natural. You are going out to do something that requires a lot of courage and self belief. It could be your first marathon or ironman or the longest ultramarathon you’ve ever done. Over the years, you’ve been bombasted with the need to fuel, the need to consume carbohydrates every hour or you die, the need to drink constantly, the need to take x amount of sodium and potassium.

Fear leads to forced protection. It leads to panic buying because you are afraid of the consequences. This is generally how modern society works too…. Life insurance, sun cream, pensions, smartphone upgrades, breakfasts, orange juice, probiotics, statins,parking sensors, gym memberships and so on. You are scared into thinking you need all these things, so you buy them.

In running terms… sports drinks, gels, electrolytes, powders, compression shorts, tops, socks, ankle protectors, GPS watches, running poles and special supported running shoes. I don’t use any of these things because I am not afraid. I’m not afraid because I understand. It’s not because I’m trying to be the tough guy. I just understand how things work and what I need and what suits me best.

I understand, through 8yrs of research and competing, that my body does not need sports drinks, gels and bars in order to fuel itself. I have programmed my fat burning engine and I know what my central governor needs and when.

This is why, in my opinion, why anyone lining up for an endurance event is loaded with all these drinks and foods. Mainly through fear. Fear that is delivered by the very companies that supply them.

Optimal Performance

I don’t think I performed to my best during this race. It wasn’t because I didn’t eat much. It was other factors such as mindset.  I felt good, ran strong towards the end and didn’t even feel empty at the finish line.

Recap – How to run 17hrs on almost nothing

–          Become fat adapted

–          Ignore the Fear

–          Control the central governor


Last thing I will say is that I think there are other things going on that allow us to produce energy. Potentially free energy. But that’s something that works in a far more sophisticated way than we can understand.


Can Carbohydrate Mouth Rinse Improve Performance during Exercise? A Systematic Review

Thays di Ataide e Silva et al, 2014.

Is fatigue all in your head? A critical review of the central governor model

JP Weir et al, 2006.

Fatigue is a Brain-Derived Emotion that Regulates the Exercise Behaviour to Ensure the Protection of Whole Body Homeostasis

Timothy Noakes, 2012.

  1. Tomek07-01-2016

    This photo, drink of champions… no comment.

    Amazing summary:
    How to run 17hrs on almost nothing:
    – Become fat adapted
    – Ignore the Fear
    – Control the central governor

    Big thanks for taking the time to share this.
    Personally I was scared of long distance because “what I’m going to eat when I’m starving; how much to take; how much prepare, etc”. Now it’s freedom—even better—so much more energy after 20 or so hours of fasting, it’s when an euphoria-like state kicks in; and the recovery is unreal—I can compare to when I used to eat only carbs. Can wait for my first ultra.

  2. Tim07-08-2016

    After the race do you slowly replenish fat stores through diet? Do you maintain your diet to keep a consistent level of body fat? Could you fast too much and reduce your body fat stores limiting the duration you could continue for. Or is 10% body fat in a normal person potentially limitless for a 30-40 hour endurance event?


    • Barry Murray07-13-2016


      Fat in muscle is what can be used the most during race. Called Intra Muscular Triglycerides (IMTG). So yes, refuelling with fats is important when fat adapted.

      Min amount of fat to stay healthy for a male is 4%…… so even with 10%BF… you still have 6% to play with…. thats roughly 30,000kcal… thats 600hours…. so thats a big ultra… and should take care of your 30-40hr ultra

  3. Ruaidhri07-08-2016

    Class read as usual.
    Fully believe and practice this

  4. Graeme05-19-2017

    Great read as always Barry. Is is hard to get/main fat adaption if you are a vegetarian? I was really well adapted when I ate meat but since switching I am finding it harder.

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