I adopted the Ketogenic Diet on 1 December 2018, partly because it seemed such a healthy option and partly out of curiosity. I am a Marathon runner and I was curious to know whether it was possible to remain competitive on a diet that is high in fat and low in carbohydrates—the very opposite of the traditional endurance runner’s diet.
I am now thirteen months into my new Ketogenic regimen and this is perhaps a good time to assess what progress I have made.
During the initial months, my experience of this radical new diet was very mixed. I enjoyed the food and my love of cooking was revitalized. I can’t remember the last time I spent so many hours in the kitchen trying out new recipes.
My hunger pangs disappeared almost overnight. I never found myself raiding the fridge just a few hours after finishing my dinner. On the contrary, I found myself doing OMAD (One Meal A Day) and intermittent fasting without even planning to do so. On the Ketogenic Diet, these things just come naturally.
I did not experience any of those initial symptoms that are generally categorized as the Keto Flu. I had done my research and taken care to keep myself well hydrated during the transitional period and to take plenty of electrolytes.
The anti-inflammatory aspect of the Ketogenic Diet is one of its major benefits for the endurance runner, and this was one of the things I noticed almost from the very start. Tough training sessions were no longer leaving me stiff and sore all over. My 3-hour long runs were not taking nearly as much out of me as they used to. This alone justified my decision to switch to this new regimen.
On the other hand, I was suffering from chronic sleeplessness, bowel problems and frequent micturition—especially during the night. The disturbance to my previously stable nocturnal habits was quite jarring. I was finding it very difficult to get to sleep at night. And when I did finally fall asleep, I was sure to be awake and paying a visit to the bathroom an hour or two later.
I was also experiencing chronic fatigue—a general lack of energy and a feeling of weakness in my legs and muscles. Walking upstairs was taking much more effort than before and could even leave me a little breathless. If I went out for a casual cycle around town on the city bikes, my legs would feel as though they had barely the strength or the energy to turn the pedals. And when I went out running, it took me about ten minutes of heavy-legged jogging to get the motor running. Initially, however, once I got over the difficulty of those first ten minutes, my runs were generally satisfactory.
Over time, however, I began to find my usual running schedule of nine hours a week very tiring. Even the three-hour long runs, which I used to take in my stride, were becoming too much for me.
These negative symptoms did not go away after the first few weeks, by which time I was probably fat-adapted (keto-adapted). But I stuck with the diet. I started taking Vitamin D supplements. I continued to take electrolyte supplements and to stay well-hydrated. On the running front, I successfully ran my first Ketogenic Marathon after five months of this new regimen (Limerick 2019). I ran with the three-hour pacemakers and successfully broke the three-hour mark (2:58:13) without too much exertion and without taking any risks. But how much of this was due to my new ketogenic regimen and how much was a holdover from my old glycogenic regimen? Five months is probably not a sufficiently long period of time for the body to make such a radical transition.
After the Limerick Marathon, I felt that I had to address the chronic tiredness problem, which did not seem to be getting any better. So I drastically cut my mileage from nine hours a week to six hours (roughly from 120K to 80K). I also cut my long runs from three hours to two hours, but to compensate I tried to run them at a brisker pace than before.
I do not know whether these changes were responsible for the subsequent improvements—perhaps I just needed time to become fully adapted to this new diet—but after about nine months of Keto, the negative symptoms began to subside. I was starting to sleep well at night. I was still getting up to urinate a few times during the night, but I was not having any trouble getting back to sleep. My bowel problems greatly improved, though there are still some issues in that area.
The most important change, however, was the gradual elimination of the chronic tiredness. My legs no longer felt weak or drained of energy. When I went out for a run, I felt that I could hit the road running without the need for a slow warm-up. I could do the 2-hour long runs at quite a brisk pace (around 4:20/K). As a runner, I was beginning to feel like my old self again.
My next big race was a Half-Marathon in Clonakilty, which was run on the eve of my one-year anniversary: 30 November 2019. Despite a very hilly course and a wet and windy day, I ran 1:25:08—twelfth place overall and first in the M50 category. The 6-hour weekly running schedule and 2-hour long runs had done nothing to detract from my performance. But this was a Half-Marathon. Perhaps it would have been a different story if I had opted for the full Marathon.
My next big race is another Half-Marathon (Carlingford on 7 March 2020), but that will be quickly followed by the Brighton Marathon on 19 April. There will be no hiding then from the consequences of my decisions. After almost seventeen months of Ketogenic training, I will probably have exhausted any leftover fitness from my glycogenic past.
I have decided that 2-hour long runs may be a little too short for a full Marathon, so I am increasing their duration to 2:20, while at the same time keeping my overall weekly mileage to 6 hours. Instead of running for 20 minutes on Sunday (the day before my long run), I will do a strength-training workout in the gym.
(Rec = Recovery, End = Endurance)
Roll on 2020!
I’m in this for the long haul ...