Fasting and productivity: what I learned from hacking my body.

Riccardo Parenti
Riccardo Parenti
Published in
5 min readAug 27, 2017


After being affected by lumbar pain caused by a disc protrusion, I started following an intermittent fasting program in order to drastically reduce my weight.
This is what happens when you search on Youtube instead of going to consult a proper doctor. As you can imagine, the fasting didn’t bring great results (maybe my method wasn’t the most effective), but it did help me to learn something I didn’t know about my body.

I realized the heightened level of focus and productiveness I achieved when skipping lunch. To be honest, going to lunch with your co-workers is more a social activity than a real necessity. Having a good breakfast and an early dinner would be sufficient enough to shrink your lunch to a serving of fruits and nuts.

Ok, I know what you are thinking now… “You are Italian, didn’t your Mom teach you about Mediterranean diet and the importance of a balanced lunch?” Yes, she did. But following my Italian food habits here in Tokyo didn’t work out well — both for my body weight and my wallet.

This is exactly what I mean when I say “fasting lunch” makes me more productive.

I created this diagram with a threshold of productiveness (that can be measured with the quality of focus I can reach), from yellow where I am unproductive to red, a phase of high focus and consequently productiveness.

On top of the productivity threshold, there is what I call the Sweet Spot. This spot is the moment where I feel incredibly focused and therefore can complete many tasks and perform at the best of my capacity. While I’m in the sweet spot, I am able to use a greater percentage of my neurotransmitters (akin to Brad Cooper’s character on “NZT” in the movie Limitless). My best design works come from a bunch of “sweet-spot” epiphanies, where I truly understood the best viable solutions and translated in design, plus a variable amount of time for production work, still in the productive area but out of the “brilliantness” of the sweet-spot.

Staying in the sweet-spot for a long time drains out my energies and I feel it’s quite difficult to remain this focused for more than two or three hours.

In a standard work day, I have breakfast around 7:00–7:15 am and get ready for work. This ritual prepares me for what is coming next. Although commuting can represent a stress factor for most people, for me it functions as the meditation time I need in order to switch my focus from personal thoughts to work-related thoughts.

When I finally start working around 9:00 am, I’m mentally prepared to gear up to full speed and get my productivity to its peak — the sweet spot.

So, what happens if I decide to go out for lunch with colleagues?

Right in the middle of my most brilliant and productive phase, I disconnect. What happens in my brain is quite similar to watching the the season finale of my favorite tv show and in the middle somebody pulls the plug on the tv.
When I come back from lunch, my stomach full of food, I’m completely out of focus. My body is already processing the food, and this involves a long series of biochemical reaction inside my body that drive to digestion. I start feeling sleepy and less motivated.
Stopping any interaction with other people when coming back to work is, so far, the worst moment of the day (food-coma). The only thing that was keeping my brain alive during the digestion process was the mental stimulation from interacting with other people. Going back to work is brutal, I understand Japanese people that culturally are unashamed of taking a nap at work for 30 minutes or so. I’m not Japanese and even if I wanted would be very hard for me to sleep after lunch.

good night folks!

So I start rebuilding the mantras to focus I had in the morning, but there is no commuting this time! Spoiler alert — coffee doesn’t work for me.
Around 15:15 I finally start feeling less oppressed by my biorhythms and slowly I start again focusing and consequently becoming productive again until reaching the afternoon sweet spot around 18:00. This time the spot don’t last too long, the day is already almost gone, and others factors start dropping my focus down like the normal stress and tiring feeling of the evening. Plus I start getting distracted by my evening appointments/programs.

Now let’s see what happen when I don’t eat lunch.

I notice that if I keep my body hydrated drinking enough water or tea, I can fool my stomach long enough without feeling hungry until 17:00.
How about the productive “sweet-spot” ??
Here’s the news, I can stay hyper-focus and productive for a longer time!

These hours are qualitatively more relevant than the standard hours out of the spot. About 5 hours of non-stop design thinking/brainstorming, workshop facilitation or visual design production!

Well, around at a certain point I need to eat a snack to push until dinner time and rarely can become productive again after it, but who cares?
I’ve been very productive for more than half day.
Ok, I know I could have a similar effect with just cutting the carbohydrates from my meal (that are the main responsible for the sleepiness), but I’ll still going interrupt my focus.
This is another fact I noticed, if I’m not in the sweet-spot I’m gonna feel hungry.

This is not science. This is just me trying to understand my body better.

What do you think?

When does your sweet spot happen?

Feel free to SHARE this article if you enjoyed reading it. Thanks!

Thanks, as usual, to my friend Elaine Westra for the support and the english editing.

Hi I’m Riccardo, a Product Designer born&raised in Italy, based in Tokyo.
I’m also the founder of community, an informational online magazine about life in Tokyo working as Designer.
Visit if you want to know more infos about living and working in Tokyo.



Riccardo Parenti
Riccardo Parenti

Product Designer born&raised in Italy, living in Tokyo since 2010.