A marathon – just add sugar

I’m stoked to say that on May 6th 2019 I completed my first marathon!

Thank you so much to everyone who has helped me raise money for Marie Curie by sponsoring me on my marathon.  I am overwhelmed by the support and kind words – and the very generous anonymous donations too – thank you – whoever you are!! ✔🏃‍♀️😃

Learn more about the background of this marathon and its fundraising.

Marathon map, Milton Keynes
42km of Milton Keynes

Three years ago I started my ketogenic (low-carbohydrate) journey, lost a lot of weight, and much to my surprise went from “couch to runner” in early 2017.  Since then, I’ve continued to experiment to see what I can do with my newfound ketogenic energy.  I discovered I didn’t need sugars and carbohydrates to do the things I wanted to do from weightlifting, cycling, running, and more.  I could do them in a completely fasted state just fuelling with my body’s stored fat.  Of course, I wanted to find out how far I could go.  Could I run a marathon without any sugar?

For my marathon I had a primary objective of completing the race, a secondary objective of completing without sugar, and a tertiary objective of completing in less than 4:30h.

I am very pleased to have achieved my primary objective!  However, it was not without its challenges, and I did NOT complete without sugar.

A sprint finish – with a bit of sugar

The experiment

My marathon experiment was to see how far I could go with absolutely no sugar or carbohydrates.  Whilst most runners were filling up with carbs and sugars in preparation and on the day, I deliberately did the opposite.  I fasted for three days before a few days of a very low-carbohydrate dieting before race day.  On the race day I didn’t have anything other than bone broth, salts and water.  This created an extreme solid baseline against which I could test how far I could run on fat / protein alone.  You can read the full protocol I used for this experiment here.

The challenges

Despite having practiced this experiment numerous times, unfortunately on race day “I didn’t feel quite right”.  After just 8km I had general muscle pain and cramping – not just from running muscles.  I continued regardless, but because I didn’t feel too good I didn’t get into the heart zone required by the protocol to minimise my use of glucose (the aerobic state).  I will probably never truly know what went wrong, however my suspicious are:

  • I wasn’t 100% well
  • I didn’t have enough magnesium
  • An unusual lack of caffeine!
I spent most of my time in heart rate zone 3 rather than aerobic 4

In any case, particularly coming up to the end of the first half things got increasingly difficult – I did not feel as energised as I usually do.  I felt negative.  That said, unbeknownst to me I was running my fastest ever half marathon distance!

I gradually slowed and found I needed a few “walking breaks” until I reached about 3:30 – about 33km when I finally had to stop – and vomited!  Yes folks, I finally got hypoglycaemia!  My blood sugars had dropped to just 2.6 mmol/L!

Blood sugar 2.6 mmol/L mid marathon (hypoglycaemic)

A spoonful of sugar

I always knew that in doing this experiment, that hypoglycaemia was a likely outcome – I just didn’t know when.  I invoked the backup plan, had two glucose tablets.

My hypo kit carried at all times

I was a little disappointed that I had to take the sugar, however this ten-minute marathon-break revealed its own interesting outcomes:

  • I didn’t suffer any confusion or disorientation that is usual with hypoglycaemic episodes.  My only symptoms were a lack of energy, and nausea.  I was able to get on, test my blood sugar and decide a course of action
  • Within about five minutes I was back up and running, within five more minutes I was sprinting.  I felt more energised, more positive and knew I would make it to the end

My guess is that high levels of blood ketones maintained my brain and essential functions – even if I could not continue to run.  Given I hardly ever consume sugar – I probably responded to it more readily than someone who uses it all of the time.

What have I learned?

Sugar and carbs are not essential to exercise

With the right adaptation and preparation – despite what sports drink / gel manufacturers told me – sugar and other junk food is NOT A REQUIREMENT for short exercises (for me probably >30km or ~3:30h).  I am certain that my liver, kidneys, and pancreas will be relieved to hear that.

Sugar can be useful when used sensibly

Sugar can be supplemented to an otherwise low-carb diet to boost performance during exercise.  Outside of this, there is no need for excess carbohydrates especially for those of us who have a sedentary day-to-day life (as I do!).  I have lived for over three years on a low carb diet and seen only positive health changes.

Ketones can win medals

Ketones keep going when sugar cannot

I have now come to understand ketones as “survival energy” – they are what keeps essential organs (not in the least the brain) functional during periods of starvation or prolonged carbohydrate restriction.  Whilst they are probably not useful per se to keep running, their presence does typically correlate with other bodily functions and hormones that CAN (to a limited degree) – such as Glucagon and Gluconeogenesis.

Ketones can be naturally raised to prevent hypoglycaemia

I now know that my natural method to raise ketones and normalise blood sugar prior to long exercises works to prevent hypoglycaemia (“hitting the wall”, or “bonking”) for as long as possible whilst consuming absolute minimal carbohydrates.  It may aid in attaining more sustainable performance from supplementary carbohydrates (also something I hope to test at some point).

Raising ketones the natural way

Where to next?

A few people have asked me if I will further this particular experiment, and whether I think it would be possible to run a marathon without sugar.

I personally believe that with the right parameters and training it would be possible to run a marathon without sugar.  I began with an extreme baseline which could be adjusted in many ways.  There could also be further work on reducing energy expenditure, and adjusting micronutrient and electrolyte balance to optimise performance.

However, having ran this experiment now for some time, I am eager to move on to new experiments on personal low-carb performance, and discover new possibilities.

For example, in the context of fat adaptation, a low carb diet and performance:

  • What difference supplementary carbohydrates can make to running speed and heart zoning (I have thus far focussed on distance and duration, not speed)
  • What different types of fats and ketogenic stimulators (such as MCT oils) can make
  • How different types of supplementary carbohydrates compare.  For example, carbs from legumes, vegetable starches, through to fruit sugars, and glucose.  Is there a correlation between performance, time and the food’s GI (Glycaemic Index)?

I also intend to continue answering the many dietary questions I get, as well as having a deep dive into lipids, cholesterol, metabolic profiles and my theories about why people are getting such mixed results from Statins…

Bye for now

Thank you so much to everyone who has helped me raise money for Marie Curie by sponsoring me on my marathon.  I am overwhelmed by the support and kind words – and the very generous anonymous donations too – thank you – whoever you are!! ✔🏃‍♀️😃

Learn more about the background of this marathon and its fundraising.

The marathon tomorrow – a quick update

One week 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!

Running on fat without sugar

What the keto?

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