6-Day Break-Fast Experiment

Eating Once a Day After My Morning Run

Christophe Berg
6 min readDec 17, 2022


For 6 consecutive days, I ate once a day after my morning run. I had a boosted colorful brunch, which I ended-up calling my Break-Fast. Break-Fast, as it took place everyday after 20 to 22 hours of fasting.



I have been practising Daily Fasting (or Time Restricted Eating) for years now. What works best for me is early TRE, meaning eating in synch with the circadian rhythm, put simply eating during daytime on a 10 hours eating window. I tend to run daily mostly in the morning so that my first meal happens after my run, regardless of its duration from 30 minutes to 2 hours. I prefer to run on empty and noticed a significant improvement in my recovery time. Now I tend more and more to eat only Twice a Day, in the morning and then around lunch time. In this experiment, I was curious to explore one step further by eating Once a Day. I have been reading about the Fast Mimicking Diet, OMAD — One Meal A Day and the combined benefits of TRE (Time Restricted Eating or Intermittent Fasting) and CR (Caloric Restriction). It seems that an induced moderate caloric restriction — 20 to 30% — explains most of the health benefits of Daily Fasting. A moderate CR is easily achievable by eating less often without having to count calories. I am not attracted by long water fasts, as it would mean being less active. I enjoy to walk, hike or run outdoors on a daily basis.

Self-Defined Constraints

  • Staying Active during the whole experiment, meaning to have enough energy daily to go for my usual run. I ended-up running a vertical trail local race right by the end of my first experiment.
  • Usual Whole Food Plant-Based Eating pattern. I have been a 100% plant eater for the past 17 years, so it’s not exactly negiotable.
  • Avoid alcohol as it tends to mess-up with my recovery, appetite regulation and disturbs my sleep. Avoid caffeine after 2pm (which I failed almost daily). Drink more water and plant infusions.
  • Avoid Calorie Counting
  • Starting Easy by setting the initial experiment to last only 4 Days.

Planning the 6-DAY Experiment

Before: Since I am already eating twice daily most of the days (5 out of 7), I just had a day of rest and recovery before starting the experiment. I would recommend to limit your eating window to 10 hours, then 8 hours depending on where you start, the 48 hours before the experiment. That’s all of the preparation.

During: on rest day, I kept the same hour for my break-fast. On Running days, I just went for my run right after the sunrise, took a coffee and walked home to eat. I was simply more mindful about hydration than usual.

After: I initially planned for 4 days but as I was feeling great, I extended it to 6 days. After the 4 or 6 days of the experiment, I suggest a smooth transition with 48 hours of progressive comeback to your usual eating pattern. In this case, I had a race at 11am on the day after the end of the experiment. So I simply had a good lunch after the race and later a soup dinner mostly to hydrate well.

Planning of the 6-DAY Break-Fast Experiment

How it went?

Cooking is already greatly simplified by eating twice a day. This time, I was almost confused from not having to cook anything. I ended up buying more food than needed. I had my usual energy bowl as the Break-Fast, which usually contains overnight oats and chia, mix with a bit of coconut yogurt, few walnuts or hazelnuts, generous spoons of peanut butter and plentiful of fruits, mostly bananas, pears or apples. I am more than used to run in the morning on “empty” meaning in a fasted state, so this was not an issue. I felt good during each run and recovered well. I had always a mint and green tea cold infusion in the fridge. I had to be careful of drinking more than usual especially during the afternoon and the evening. My healthy weight is kind of stable while I am training in endurance — it starts to swing when I don’t run on a regular basis or if I tend to drink a bit too much. My weight stayed stable during the whole experiment, just going down of one kilo by the end to comeback quickly the week after. Since my goal is to maintain a healthy weight, I was pleasently surprised.

Morning Vertical Run on El Time — Tazacorte — La Palma — Canary Islands — Photo by Alexis Berg


The first two days, I felt hunger around lunchtime as I am used to eat at this time of the day. By day 4, I had no hunger anymore, I felt energized, more alert and focused at work. I was careful to eat more by day 5 and 6, as I was worried to feel weak during my vertical trail race on Sunday. So I had some rice or quinoa with veggies as a second bowl for each Break-Fast. Honestly I think that it was more a mental thing than a necessity. But that’s the idea of an experiment to adapt and adjust according to your own sensations.

Morning Vertical Run on El Time — Tazacorte — La Palma — Canary Islands — Photo by Alexis Berg

Running Daily?

I like to practice on a regular basis about 4 to 5 times per week. I do mostly short runs on the trails around my place. I live on a small volcanic island — La Palma — where flat trail doesn’t exist, all trails are vertical ones. I do mostly short runs of 40 minutes to 1h20. After my run, I swim in the ocean whenever it’s possible. I have a coffee before heading home and having my post-run meal. You can look for the types of trails on lapalmatrails.com

I explain in an article why I enjoy running almost daily.

A Book — in French- on Daily fasting, my initial experience and few experiments

I am the author of a book on Daily Fasting: “Secrets du Jeûne au Quotidien” aux éditions La Plage, Paris. More about my books in French.

Secrets du Jeûne au Quotidien — les éditions La Plage — Christophe Berg

And I shared on MEDIUM about my initial experience of Intermittent Fasting as well as few others experiments:

Don’t hesitate to connect of you have questions. You can find me on my webpage kristofberg.com or on Instagram at kristofberg



Christophe Berg

Lifestyle Business Coach | Wellness Consultant | MS in Project Management 🎓 | 🗣️🇫🇷🇺🇸🇪🇸 | Nomadic Trail Runner