Disclaimer: This article is for entertainment purposes only. I am not a doctor nor pretend to be one, so please do not qualify this as medical advice. The content of this article is not intended to be a substitute for professional medical advice, diagnosis, or treatment.


At 8:00 PM on Monday, July 29th, I took my last bite of food for the next 72 hours. I was giving up all meat, vegetables, fruit, grains, and alcohol for the next three days. I would not be picking up a fork, knife, or spoon until 8:00 PM on August 1st.

So, you’re probably thinking to yourself, “Why would anyone do this?”

Why Fast?

I grew up with the assumption that being healthy meant you were supposed to eat three square meals per day. I never even considered skipping breakfast except for a few times in college when I was running late for class. My life, it seems, has always revolved around my next meal.

But how normal is eating three meals per day?

Growing up, I never questioned my eating habits because I was always hungry every 4-6 hours. But was my hunger a product of being conditioned to eat at those specific times? Or, is there a biological element to the spacing of my meals?

A quick look back through history would give evidence to the former since it appears eating three meals per day is as modern as the Industrial Revolution. What I considered to be normal is only 260 years old. Eating three times a day was born out of necessity to accommodate the typical 9-5 workday as a matter of convenience.

So, if the idea of eating three scheduled meals per day is as young as the Industrial Revolution, what is considered a normal eating routine?

Going back further in time and we arrive at the beginning of the Agricultural Revolution some 12,500 years ago. For the first time in history, man was able to settle down in one spot to grow and cultivate food. Agriculture also gave us the ability to store food to hedge against an unpredictable future.

But since the dawn of homo sapiens (some 300,000 years ago) up until 12,500 years ago, mankind had to survive on unreliable access to food as hunter-gatherers. There were no restaurants, farmers markets, or convenience stores to travel to when you were hungry. You either were able to find some nuts, berries, or roots to munch on or were lucky enough to hunt down a deer to feed yourself for the next few days. Otherwise, you went to bed hungry.

Nearly 300,000 years of humans having unreliable access to food is strong evidence to believe that our bodies are well equipped to go without food for a couple of days. When viewed through the lens of history, fasting is more natural for our bodies than consuming the modern American diet consisting of modified grains and excess sugar.

Thankfully, we no longer have to scavenge for our food due to the collective intelligence of humankind and the technologies that have made food cheap, abundant, and convenient. But our modern comforts have brought along a host of problems in the form of obesity and disease. We live in an era where millions of people are diagnosed with diabetes, cancer, and a variety of autoimmune diseases every year.

Perhaps we have gone too far in the opposite direction when it comes to our relationship with food. We eat past the point of satiety, eat during all hours of the day, and consume copious amounts of sugar that would have been unimaginable to somebody living even two centuries ago.

Our modern diet, paired with constant eating, has left us lazy, sick, and overweight. We have drifted off the path that nature intended, but fasting could be a useful tool for getting our body back to a more “natural” state. It also provides a host of immediate health benefits.

Health Benefits of Water Fasting

Fat Loss

The benefit most commonly associated with fasting is weight loss. The weight loss occurs once your body goes from a fed state to a fasted state. With no food to burn for energy, your body begins burning body fat (stored fuel) to keep running.

You’re considered to be in a fed state when you’re digesting and absorbing nutrients from your last meal. The fed state lasts 3-5 hours after your last bite and is the most difficult stage to lose weight due to your elevated insulin levels. Your body will then reach a post-absorptive state 8-12 hours after your last meal, where it isn’t processing any food.

Once you hit the 8-12 hour mark without food, your insulin levels drop as you enter a fasted state. Your body now has to burn body fat to provide itself energy. Prolonged fasts can result in you burning 1-2 pounds of body fat per day*.

*If you are considering fasting for the sole benefit of fat loss, you might be incentivized to continue your fast past the point of what is deemed safe and healthy. Please consult with your physician before you plan to perform a prolonged fast.

Autophagy

A primary benefit of fasting is the process of autophagy. Autophagy is the body’s natural process of breaking down and recycling unnecessary or damaged cellular components built up in your body. It is an essential mechanism for starving damaged cells that can lead to disease, including those that form cancerous tumor cells.

There is also supporting evidence that autophagy plays a role in increasing longevity and healthspan. A 20+ year study of rhesus monkeys (which share 93% of our DNA) measured how restricting calories of the Calorically Restricted (CR) Group by approximately 30% lowered their rate of age-related diseases by nearly 3X of the Control Group.

Insulin Sensitivity

Research has also shown that fasting improves insulin sensitivity. Insulin is the hormone your body releases when you begin the process of breaking down your food so it can absorb the glucose (sugar) into your bloodstream. Glucose is the fuel source used by your cells so they can continue to function.

Insulin is vital because, without it, your cells won’t receive the signal to accept the glucose in your bloodstream. If your body senses that glucose isn’t being absorbed by your cells, it will eventually store it for later in the form of body fat. The more insulin sensitive you are, the less likely your next cheat meal will go straight to your belly or thighs.

My Fasting Experience

For 72-hours straight, all I consumed was water except for one cup of black coffee in the morning. Fasting “purists” will claim that having one cup of black coffee each morning constitutes as cheating, but I allowed it for the sake of my sanity. I stuck with the same daily routine except for opting out of weight lifting (explained later) during this experiment.

Below is a recollection of my experience of going three days without food.

Day One

Tuesday was my first full day of going without food. My day was like any other except for not taking the time to eat breakfast, lunch, and dinner.

The only time I experienced any hunger pangs were around 7:15 AM when I typically eat breakfast, 10:30 AM when I have a light snack, noon when I break for lunch, and around 7:30 PM when I eat dinner. The hunger pangs only lasted 10-15 minutes before subsiding, so I had no trouble waiting them out. The timing of my hunger wasn’t surprising since my eating schedule stays reasonably consistent during the weekdays. Outside of my regular eating hours, I did not experience any hunger.
The most challenging part of day one was figuring out what to do with the additional spare time I had that was usually devoted to eating. I had a busy day at the office, so working through lunch made it easy to distract myself from the thought of food. Dinnertime was much more difficult, however. I decided to leave my place to go to the library to distract myself with some personal work in an environment that wouldn’t tempt me with food.

I got in bed around my usual time and had no difficulty falling asleep. My sleep data shows I had no problem sleeping through the night even while on an empty stomach.

Sleep data day 1

Overall, day one went as well as I could have asked. I think it was rather easy because this was my third time completing a 24-hour fast, so I knew what to expect. But tomorrow will be the first time I have gone longer than a day. Day two is when the real challenge begins.

Day Two

I woke up feeling more alert than usual. I expect this is due to my brain running on ketones since I am in full ketosis by this point.

The morning felt similar to the day before, except I did feel a little lightheaded. It was somewhat bizarre having a feeling of increased alertness and mental energy while simultaneously getting a sense that your physical stamina has lowered. The lightheadedness came and went throughout the day but never reached a point of being a real concern.

By late afternoon, I finally had to deviate from my routine schedule. Based off a quick self-assessment, I decided to play it conservative and take the day off from lifting weights. I could have probably endured a light workout, but I didn’t want to risk getting more lightheaded or dizzy.

Despite not eating for over 36 hours, I’m not hungry. Going without food has been a breeze so far. I had another busy day at work, so I was able to keep myself distracted through lunchtime. It felt like a regular day except for experiencing a sensation of lightness, almost like I was floating, when I got up from my desk to move around.

Everything was smooth sailing until dinner time when I visited my girlfriend and her family for a celebration dinner (made known to me after I started the fast). A plethora of food and drink surrounded me. There was no way I could distract myself from the thought of food like I was able to do yesterday. I had to look temptation directly in the eye while everyone around me enjoyed the feast.

Surrounded by food, my hunger is surprisingly less than what I experienced yesterday evening. But once 7:30 PM rolled around, I started to experience a mild headache and tiredness. The headache continued to ramp up throughout the evening until 10:00 PM when it finally started to subside. It felt like I was experiencing a mild hangover.

By the time I got in bed, I was tired but didn’t have much trouble falling asleep. Once again, I slept soundly through most of the night.

Sleep data day 2

Day Three

Last night I experienced some of the most lucid dreams in recent memory. I typically have a hard time recollecting any part of my dreams, but I woke up remembering long stretches and even minor details. The clarity of my dreams has me believing that my sleep quality has vastly improved.

Day three played out like the previous two days with my hunger only being noticeable around mealtimes. If anything, it was easier to get through the morning than the last two days. I still have the sensation of lightness but have perfect mental clarity.

However, once 12:30 PM rolled around, I experienced some of the sharpest hunger pangs yet. I decided it would be best to get out of the office to distract myself in a new environment, so I drove to a nearby park to walk in the woods. I did a brisk 20-minute walk on mostly flat terrain but was surprised by how elevated my heart rate was by the end of it. Once again, I decided it would not be a good idea to lift weights later in the afternoon.

The hunger stayed with me for the next two hours. At this point, I am really starting to miss food. I daydream about what will be my first meal to break the fast once I hit the 72-hour mark. The hunger never becomes unbearable, but I find that my day is less exciting without the enjoyment I get from eating. Perhaps I derive too much pleasure from food.

The mental clarity and focus I’ve been able to sustain throughout the day have been the most significant benefit of fasting. On most days, I eat a rather big lunch (for the sake of building muscle), but it tends to kill my productivity in the afternoon. Having to digest a big lunch usually results in brain fog and lethargy for the next hour or two. But today I never experience any decline in energy until the end of the day. It honestly feels like I have a superpower.

But alas, 8:00 PM arrives and I am ready to end this self-experiment. I feel well enough to extend the fast for another day, but I want to mitigate any loss in muscle mass. I’m also ready to celebrate with a delicious meal.

Breaking the Fast

Since I only fasted for three days, I disregarded the risks of refeeding syndrome. Instead of slowly introducing food back into my diet, I decided to celebrate by going to one of my favorite Korean restaurants to scarf down some pork dumplings and bibimbap.

Pork dumplings
Bibimbap

Final Thoughts

Overall, the fast was much easier to complete than I expected. Other than a minor headache on the second day and not feeling fit enough to lift weights, it was a positive experience. If anything, it taught me that I could perform well, if not better, with regards to mentally taxing work while in a fasted state. I suspect this is a product of our evolution since having heightened mental clarity when hunting for food would provide a higher rate of success.

One motivator for completing this challenge is the idea of hormesis described by Nassim Taleb in Antifragile. Hormesis is the process of periodically exposing yourself to acute stressors so you can build up a resistance to future stress. Fasting, along with weight lifting and running are prime examples of exposing your body to acute stress to create a more robust and healthy body for the future. Along with the health benefits listed previously, fasting also boosted my mental toughness since I now know I am capable of going without food for a couple of days if needed.

So, would I do it again?

I think so. I probably won’t do it again for quite some time, but the health benefits seem to outweigh any temporary discomfort. If anything, I will continue to do an occasional 24-hour fast. I now consider fasting to be a useful tool when access to quality food is scarce, such as when flying for long periods. Even not eating seems preferable to most of the food served on airplanes.