What happens if you don't eat for 72 hours?

If you are reading this, you are likely satiated enough to dedicate some time to read what I have to say about an extended fast. Perhaps this direct confrontation with food has made you evaluate how hungry you are right now. Have a snack, or a drink of water, and I invite you to truly delve into the emotions summoned by such an action that we do extremely commonly. It is no secret that humans are self-centered, the universe revolving around ourselves, with every little issue seeming to have the power to dominate our existence and perhaps even overwhelm our psyche. As a thought experiment, what would happen if you began suffering from a self-induced period of not eating? Do you become faint and weak? Do you become inspired to eat unhealthier options of food? Do you grow angry at others? Having studied biochemistry through the lens of the human metabolism, we should be fine. But... every day at some time between noon and 3 pm, my gut begins begging for nutrients. My head begins irritating me with this steadily building pounding as I need food, and I need it now. I become easily irritable, hangry, and as Snickers says: "You're not you when you're hungry".

So where is the fine print? Who is telling the truth? The science books or my gut? In a modern-day odyssey, I attempted to tackle the ludicrous quest of only drinking water for a period of 3 days. Throughout these 3 days, I attempted to say active, with the daily commitment of a 4-mile run at a steady, yet slow pace.

If my Hispanic mother is anything like yours, she could not comprehend how or why her child would withdraw from food that our society possesses an exorbitant amount of. A Cuban immigrant who's primary reason for defecting from her homeland was lack of food, would refuse to accept this self-induced period of suffering. She promised me that if I did not eat, I would suffer from an insulin shock as a result of extreme hypoglycemia and I could potentially die on this foolish journey. I trusted the extensive hours of research I have dedicated to understanding how the body can produce the necessary glucose for my existence, and I transformed into a nomadic hunter on the search for food, from tens of thousands of years ago.

24 Hours of not eating

Following a hearty breakfast that filled me up well beyond my necessary needs for sustaining energy, I decided to embark on 72 hours of only water. I know that zero calorie alternatives of coffee and tea are also fine, but I have always loved water and it was she that I would trust to take me to the promise land that seemed unattainable at the beginning. As a serial midnight snacker, the first night was perhaps the hardest period of suffering. Prior to commencing the fast, I would often raid the pantry and indulge in some generous amount of calories that would satiate my stomach and allow me to sleep peacefully, a little bit like Winnie the Pooh if you want a clear visual.

The following morning, was accompanied by strong hunger pangs, as the peptide hormone ghrelin has adapted to spike at such hours. Ghrelin is responsible for stimulating your appetite and is the reason you feel hungry around the typical hours of the day that you eat food. I have grown accustomed to the privilege of a well-balanced breakfast following a night of sleep for 23 years. At this point, I am approaching the end of the first 24 hours of no food, all glucose and glycogen stores in my body should have been depleted and my body must now begin oxidizing fat (triglycerides) to produce fatty acids that would then undergo β-oxidation to extract the necessary ATP for my body to function.

If this is foreign to you, I thought of a simple way of breaking it down that should be easy to understand without any knowledge of biochemistry. When you consume food, your body converts it to dollar bills. Dollar bills are really easy to use. If you go to a store and need to pay 5 dollars you can give 5 one-dollar bills and the transaction will be extremely simple. Excess dollar bills can be consolidated into a dollar bill of greater value such as a 5 dollar bill, or a 10 dollar bill. The singular dollar bills can be thought of as glucose and the greater value dollar bills can be seen as glycogen. Glycogen is a branched polymer (from the Greek word many parts) of glucose itself.

There is only a limited amount of glycogen that the body can store, so excess glucose at this point is stored in triglycerides or fat. Following our real-world example, these can be imagined as spare change. You typically get a little bit of spare change with every monetary transaction you have, in itself not life changing, but it can very easily add up to something big. Imagine the same 5-dollar transaction at a store, but this time you only have spare change. In this fantasy world, you carry all the spare change you've ever collected in a bag right in front of your gut. There is no question you have 5 dollars worth of spare change to complete the transaction, but it will take a lot longer and will be harder than our dollar bills that we are so used to. This is precisely the metabolic process that would be taking place in my body from this 24 hour fasting period onwards.

48 Hours of not eating

The morning hunger pangs following waking up, were present during the hours of lunch, dinner, and specifically for me midnight snacking. My trusty sidekick, cold water, was able to powerfully remove any desire to eat for about 2-5 minutes with each sip. This battle against my mind and my body would typically take place for about an hour or two at each of the aforementioned times. Between the hours that I would typically eat, I felt perfectly fine!

There are a significant number of health benefits that should be taking place at this stage such as the increased production of human growth hormone (HGH) as well as autophagy (meaning self-eating of useless cells in the system). I won't pretend to know about these aspects of metabolism to the level I claim to understand the relationship between glucose, glycogen, and triglycerides. I will however anecdotally mention that I felt mentally sharp; similar to a feeling I could acquire after 1-2 cups of coffee. My focus was enhanced, my attention was easy to control. I was able to sit at the computer for 4 hours straight doing monotonous chores that I have been putting off for a long time as they seemed so boring I could rarely bring myself to even begin them. When competitively gaming, something I do often as can be seen in the clips section of this website, I felt a mental clarity to my decision making that I have never felt before. To others it may not mean a lot, but I was matched against Grandmaster and Top 500 players of Overwatch 2 (OW2) and was able to not only keep up, but make game winning plays with my utility that awarded me praise from my teammates that are infamous for spewing toxic insults at the slightest discrepancy in gameplay. For the unaware, I will mention that OW2 frequents 25 million monthly players and from those that choose to play the competitive game mode, only the top 3% can earn the title Grandmaster and only the Top 500 can be considered the Top 500.

Perhaps a placebo, perhaps the truth, I can not deny how mentally incredible I felt during the 24 hour to 48 hour window of fasting. I was able to maintain the steady slow pace of 4 miles of running and even threw in 100 pushups as a workout that might damage some muscles to see if the HGH effects of increased muscle repair were true. Although I realized I am not really sure of a good way to measure increased muscle repair.

72 Hours of not eating

The last 24 hours of the 72 hour fast were not easy. I knew I could fight the hunger pangs with water and I know I could survive if I survived this far. The difficulty at this point was no longer physiological, it had become extremely difficult mentally to stay committed. From my research, the health benefits had reached their capacity and would continue to function at this rate for the remaining 24 hours, but it hurt my motivation knowing that the benefits were not somehow becoming stronger. At this stage, I can not attest to an increased coffee-like mental clarity. Instead, my mind was filled with thoughts of food. These were not consensual thoughts being produced consciously. In a fascinating display of spatial navigation, depending on which direction I was facing, my mind would be filled with the idea of what delicious foods awaited me if I headed in that direction. In some complex form of neuroscience, my head direction cells were communicating with my amygdala and hippocampus to elicit memories of delicious foods that only heightened my hunger.

During this window of fasting, each second became a little longer. My ability to be mindful of my place in the universe increased. I was able to think more about my relationship with people I love. And how sometimes we take for granted these people the same way we take for granted food. Take this opportunity to think about the people you love, and think deeply about why you love them. You may notice there are a lot more reasons than you might guess.

The 3rd morning, I broke the 72 hour fast at hour 70 with a chicken bone broth that I had been awaiting with great satisfaction for a long time now. The warm healing elixir took me about 25 minutes to down as I cherished every spoonful of the broth. Although, satisfying for the soul, it can not be compared to the incredible taste of the chicken and tomato meal I had about an hour or so later. Writing this now, my mind is filled with the colorful fireworks that were going off in the deepest parts of my brain with each bite of that meal.

Should you fast for 72 hours?

As a survivor of this rather unique experience, I can not say with confidence that anyone should do this. You require a certain level of crazy to commit to this much time without food. Everyone is different and there is no way of knowing your system will react like mine. I am not sure if I appropriately conveyed how difficult this process was. The thought of food only became more present as the time went on, and the urge to eat grew stronger with each hour. It was only through sheer will and sunk-cost fallacy that I was able to continuously refuse the delicious thoughts of food that would invade my mind.

Instead of diving head first into 24 or 72 hours of fasting, I would recommended fasting for 16 hours and eating for 8 hours, intermittent fasting. The health benefits in this domain are also prevalent although I have not researched them. If you are perfectly content with your eating habits, then I applaud you and I instead invite you once more to mindfully consider the people you love in your life.