One week to go

With my first ever marathon coming up in one week’s time (6th May) some have been asking about my latest preparations.

In many ways I have been preparing for this event since I started my low-carb / ketogenic diet back in April 2016.  Since then I lost a lot of weight and as I became energised, I became interested to learn how far I could push myself in this new found state.

10th May 2019 update: see A marathon – just add sugar

I am following my very own protocol, which I created built on years of study and self-experimentation.  I finally documented this in March 2019, and often refer to it myself to keep on track!

Running on fat without sugar (the protocol)

What do I eat?

My dietary goals

Day 1Day 2Day 3Day 4Day 5Day 6Day 7
FastingFastingFastingHigh fat
High fat
High fat

In a nutshell, over the last few months, (since my half-marathon in December) I have become stricter about my diet -(and yes, I do look forward to being a little less strict soon), and increased my running distance over time.  I have tried my best to perform these runs in varying conditions, trying out different gear, terrain, and techniques.

There would have been more I would have done, if I had the time.  I don’t feel I have done nearly enough resistance and general “movement” training.  This would have helped me to prevent possible injury.  I look forward to getting back to bodybuilding after the event (maybe not straight away!).


I have now got to the point in the plan where I am taking regular blood measurements and weighing in.  The protocol states that at this point:

  • I should feel energised and well
  • I should not feel overly thirsty, my appetite should be normal
  • My fasting ketones will likely be in the range of 1-3 mmol/L
  • My blood glucose will likely be around 4.0 mmol/L

✔ So, I’m a bit tired due to lack of sleep lately but otherwise I do feel energised and well, appetite normal (apart from on my last big run), no excess thirst.

✔ My ketones are measuring in at 1.6 to 1.9 now (ideal).

✔ My blood glucose is about 4.2 (ideal).

So far so good!

The final week (this week) is a bit more complicated.  It involves a two/three day fast (electrolytes only, bone broth, salt, water, black coffee only), magnesium and vitamin supplementation, followed by two/three days of strict ketogenic dieting (<5% carbs, 10 to 15 g daily).

At the time of writing, I have just started the fast.  Fortunately, I did “at the last minute” manage to gain some weight prior to this.  A regular “side effect” of fasting is of course weight loss.  Losing a little weight is helpful for a run, but I do not want to lose fast-burning fat fuel either!

I gained some weight yay!

At the end of all this, I should see:

  • My fasting ketones will likely be in the range of 3-4 mmol/L
  • My blood glucose will likely be around 3.5 mmol/L

This whole process stimulates, and “trains” the body’s functions that create energy without carbohydrates.  The aim being to maximise my ability to create energy (glucose + ketones) responsively, on-demand to get me through the event.

Will it work over 42km?  I do not know, as far as I am aware it’s not been done before (without any supplementary carbohydrates).  I might need to supplement during the event after all, and it’s for this reason I will be carrying some glucose tablets.  We will see!!

My weight and measurements taken over the week will show up as I record them in the above embedded chart.  I expect to see my ketones rise and my blood sugar fall initially, before stabilising at the end of my fast.  Ketones should be attenuated somewhat after I resume eating, but then should be ready to rise fast on the day of the event. As I’m doing a 3 day fast, I do of course expect to lose some weight – but hopefully not too much!

With that, a little luck and not too much sunshine – I should be good to go!

Find out more about my Marie Curie marathon in memory of “my third grandparents”

32k, heat, teddy bears, and sugar pills

30km running distance record achieved!

23km run in a fasted, low-carb state

Running on fat without sugar

What the keto?

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