Why I might stop intermittent fasting
Increasing the training volumes, body recovery and meeting the calories target. Is intermittent fasting still a good ally?
I am a big fan of intermittent fasting. It makes me feel great, it improves my sleep, my digestion, my focus. It improved my insulin sensitivity, blood glucose stability and I consider it a key factor in my 90% time in range challenge - which in turn facilitates weight and body composition control.
I think everyone should try some form of time restricted feeding. Its benefits extend much further than mere weight loss: you’ll focus better, improve your self-discipline and self-control and feel mentally and physically lighter.
So far so good…but…
Since a couple of months I started to run again, adding a couple of zone-2 long(ish) runs per week on top of the strength training. Physical exertion requires rest and recovery. Workouts are a stressor for the body, which will need some time to adapt to the stress induced and recover from it. This adaptation occurs through physical recovery and nutrition. I am a big sleeper and routinely do mobility and stretching routines, so resting is not an issue. But the metabolic window that opens right after a workout is critical to kickstart the recovery, since the body will grab as much nutrients as possible from food in order to “rebuild” the destroyed muscle fibres.
While doing one workout per day, all was fine. I felt fully recovered and ready to go at each new round.
But when the running increased, I started to experience some extra fatigue towards the last few miles of every run, which I typically do right before breaking the fast, i.e. at the end of the 19 hours fasting window. My insulin sensitivity and glucose stability still being great, my performance started to suffer a bit, and the feeling of unrest started to compound, leading me to a plateau in strength training and fatigue during my runs.
Trying to figure this out
I listened to this episode of the Trail Runner Nation Podcast, where the guest Coach Bob Seebohar raised a point I had never considered before: all the benefits of intermittent fasting are true, but research about intermittent fasting has been done extensively on sedentary/normal people…not as much on athletes!
In the podcast he highlights that it takes up to 24 hours for carbs gas tank/glycogen stores to get replenished and for our body to be able to take the physiological adaptation induced by a work out. With one workout a day, that is manageable. With more workouts per day, and more intense, this could mean that my fasting protocol is consistently getting in the way of recovery and performance.
I am also struggling a bit with meeting the calorie target. To maintain my bodyweight and composition, I need around 3000kcal these days, and eating such an amount in such a short window can be hard, unless one consumes a lot of hyper processed foods which are high refined carbs and fats (thus, in calories).
Since I do avoid all those foods in favour of whole plant based foods that promote good insulin sensitivity, I will probably have to widen my eating window, if not put it on hold as long as my running volume increases.
I am not sure how to proceed exactly. I have brainstormed my thoughts and listed down my doubts about intermittent fasting and other considerations about its intersection with running in a couple of posts in my blog.
I have no answers, and I surely invite you dear reader to give your two cents or share your experience.
Looking forward to hear from you!