After running 42.195 KM in Valencia on nothing but water and electrolytes, I am more than thrilled to share this amazing experience with you. Since I ran my first marathon in 2017 on a high-carb vegan diet, I thought it would be an awesome idea to try running a marathon on keto as a sort of N=1 case study. The reward? I broke my first marathons time with 50 minutes, and I totally experienced a runners high along the way. Are you a runner who is interested in thriving on a keto diet? Find out how I did it and experience it yourself!
In this article, you can read about my personal experience and my view on this journey. In addition, find information on my nutrition and training program before the marathon, nutrition during the marathon, and how I recovered after the marathon.
Which differences did I notice according to performances and energy levels, compared to last year’s run?
WHY I GAVE RUNNING A MARATHON ON KETO A SHOT!
The time of carbohydrate loading and eating bananas before a race, and taking sugary sport gels and drinks during runs might be over soon. There is growing interest in using fat as a primary fuel and carbs are no longer seen as the only efficient energy source for long-distance runners. Currently, an increasing amount of endurance athletes covering extreme distances such as triathlons decide to run on fat. Jeff Volek, Stephen Phinney, and Tim Noakes spent decades studying the effects of a low-carb, high-fat approach in endurance athletes, and more and more research indicates that a ketogenic diet can have significant positive effects on energy levels and endurance performances.
To be able to provide the best advice to my clients with a goal of improving their endurance performances, I decided to bring everything I learned over the last year into practice.
So what did I exactly do to be able to run in a fat-adapted state, and how did it end? Before we dive into the practical aspects of running a keto marathon, it is important to understand the differences between the mainstream way of carb-loaded running and the groundbreaking way of fat-adapted running.
IT TAKES MONTHS OF DEDICATION TO BECOME FULLY FAT-ADAPTED
Of course, running a marathon on keto is not something you can decide the week before your race. It takes a lot of determination, dedication, and months of training to benefit from fat-adapted running, and to efficiently burn stored fat for energy. In July, I started to reduce my carbohydrate intake till a maximum of 30 grams per day. Falling off the wagon during the first weeks was not an option, since you basically have to start your ketosis journey all over if you do so. You have to realize that becoming a fat-adapted runner requires a complete physical and mental lifestyle change! Basically, your whole life starts to evolve around your trainings, and eating keto.
Luckily, it’s all worth it, and a high-fat diet provides a steady long-lasting energy fuel throughout the day. I allowed myself at least one month to get used to this new lifestyle, and to slowly build up my mileage per week. Therefore, starting the ‘most intense part’ of my training program was actually not as hard as I thought it would be!
I only experimented with fasted running after 2 months, because if you’re not fat-adapted yet, you won’t experience a lot of benefits from it. Also, I never ran more than 1,5 hour in a fasted state, and I always ran right after waking up. What I noticed, was that both my energy levels and average speed increased from doing these runs.