While we are all running alongside (and thinking of jumping on) the intermittent fasting train, who is up for a bit of a challenge? My daily feeding pattern includes up to 20 hours without food and I regularly, for a number of different personal reasons, abstain from food for periods lasting over a day. So when I decided to fast for 60 hours I thought, “What could go wrong? Or right?”
For those who haven’t come across one of the multitude of sites endorsing intermittent fasting as a viable feeding pattern, here is a Cliff Notes version of the purported benefits. Despite what you were taught in school and what your personal trainer has told you, modern science has essentially proven that there is no metabolic magic in eating when you first wake up, and there isn’t actually a lot of scientific substantiation for the supposed physiological and satiating benefits of three square meals or six smaller meals a day. Also, there is little evidence to support the adage that your body can process only so much nutrition at once; in fact, as a survival mechanism, the amazing human body has developed the ability to continually alter macro and micronutrient absorption timing. If need be, research has shown that the breakdown of protein can take place over a long period of time, so that mass consumption in a shorter period of time provides no appreciable difference on the body than if it were to be spread throughout the day. Meal frequency and timing simply is not as important as quantity and quality of food. From an exercise standpoint, fasted training can actually result in enhanced metabolic adaptation. Furthermore, there are indications that training on empty may improve post-workout protein synthesis and anabolic response. Believe it or not, there is also a growing body of research delving into the implications of fasting and brain health, and one of the hottest areas of health science, autophagy, is exploring the possibilities of fasting as a means to improve overall health.
The science aside, as my over two decades of primary research and study and my personal experimentation in nutrition and exercise continue to prove: we are all very distinct beings, with individual responses to input. What the science says and what works for me may be irrelevant for your life. I have found that intermittent, and sometimes extended, fasting works for me for several different reasons. My very rigid and compartmentalized Asperger’s brain works best focusing on one thing at a time. With intermittent fasting, I can focus on my work from 8 am to 4 pm, then switch to refueling from the destruction this activity causes (and focus on my wife and kids, of course) from 4 pm to 10 pm, and then switch to physical rest until the next morning. Each task of the daily cycle is most efficiently accomplished when it is the only task—multitasking doesn’t happen. Furthermore, those gastric mechanoreceptors of mine don’t function normally; in other words, my jaws work a lot faster than the communication between my gut and brain. Am I “full”? What does that mean? If I am eating several meals throughout the day, the number of opportunities to overfeed are too numerous for my own good (and that of my belt). Additionally, I have no health concerns that would make periods of abstaining from food contraindicated (particularly issues involving blood glucose regulation). Intermittent fasting works for me, but it may not work for you. You should consult your physician before making any decisions about something as important to your health as your feeding patterns.
So, why 60 hours? Well, personally, 24 hours has been done more times than I can count and a recent 48-hour fast I did went remarkably well; it was far less difficult than I could have imagined. No point in doing something I’ve done before when this is about personal development. Personal goals aside, as a scientist, it all comes down to the data. Contrary to an oft-repeated nutrition myth, your body doesn’t go into starvation mode, slowing and shutting down metabolic processes in order to preserve energy, if you skip breakfast. In actuality, with intermittent bouts of food abstinence, basal metabolic rates often respond with recurrent spikes in short-term fasting, with your metabolic fire being stoked 3%-10% after up to 48 hours. The earliest measurable evidence of decreased metabolic activity appears to occur around the 60-hour mark, where one study showed an 8% decrease in basal metabolic rates. Other studies have shown that measurable negative responses don’t begin to occur until 72-96 hours or more. But, let’s not get carried away. I wasn’t about to skip the monthly family potluck and its legendary burrito bar. So the research suggests that negative consequences may begin to creep their metabolic-slowing heads around 60 hours, so 2.5 days it was.
And this is what happened.
I didn’t feel hungry.
Of course, this is very subjective. As someone who regularly fasts for extended periods of time, I am less sensitive than the average bear to those mechanical satiation cues of correlated hormonal responses that trigger our brain to tell us we are hungry, but there is actually quite a bit of research to suggest I am not alone in this feeling (or lack of) during fasting. On the morning of day 3, 55+ hours without food and my return meal clearly in sight (literally in Tupperware on my desk), I was looking forward to breaking the fast, but the expected hunger pangs simply weren’t there. I stared at my chosen finish-line meal—about ½ lb. of the wife’s homemade beef meatballs, a cup of green beans, spinach, and a tablespoon of natural peanut butter—with envy, but my mouth wasn’t literally watering. And then when I partook, it was delicious (the secret recipe behind my wife’s Dr. Damian-approved meatballs will one day start a war), but I wasn’t overcome with the initial rush of energy and positive endorphins that I expected. Actually, I felt full and tired about halfway through. I, Damian Rodriguez, shamefully admit that I did not finish a meal and had to polish off the remains about 3 hours later as I was preparing for my midday workout. While one of the primary concerns with fasting is that the process and its correlated hormonal responses turn one into a ravenous, bottomless eating machine once the fast is over, I have never personally experienced this, and the effect was even more muted after this extended fast.
I didn’t feel weak.
My workouts throughout the 60-hour fast were great. There might even be pictures circling around social media to prove it. I was under no delusions that I had just downed a double serving of pre-workout, those squats felt just as heavy as they normally do, but my performance was affected very little, if at all. Of course, I’m not some exercising cyborg; science can easily explain why I didn’t experience drastic decreases in performance even though my body was forced to find alternative means to force energy into my muscles. One study found that 3.5 days of fasting resulted in almost no perceivable impairment of anaerobic capacity or low-intensity aerobic performance. In fact, there is some evidence that endurance training performed in a fasted state may yield greater improvements in fuel utilization and can boost muscle glycogen storage efficiency. There are various theories as to how and why this may happen (most involving terms like citrate synthase and 3-hydroxy-CoA dehydrogenase), but the bottom line is that you would be amazed by how you can perform in a fasted state. Furthermore, there is an interesting new theory with some intriguing evidence that fasted resistance training may provide an additional stressor our body is forced to adapt to; in essence, fasting may help create an environment where our body’s homeostatic mechanisms that control development literally have no choice but to progress. Greater stress hypothetically results in greater adaptation, or so proposes one of the foundational principles of exercise physiology (progressive overload).
I didn’t feel angry.
The “hanger” is not real. Actually, we know it is. And there is a scientific foundation for this phenomenon. The condensed version: the area of your brain (the prefrontal cortex) that regulates self-control requires energy, best provided by a steady stream of glucose via carbohydrate metabolism, and in the absence of this brain fuel, one tends to become agitated and aggressive. But, I can’t say I experienced it during my fast. I didn’t irrationally lash out at my wife or colleagues. I was pleasant, perhaps uncharacteristically so. Maybe it was because I was in the midst of another one of my exciting (to me) human experiments or that my body has just adapted and become more effective at providing fuel to my prefrontal cortex. Either way, the fast finished with my marriage and my employment still intact.
I was laser focused.
Another interesting occurrence during my 60-hour fast was that I was particularly productive. You may think that a dearth of glucose to the brain would impair cognition and motivation to work, but, as my previous experience has also spoken to, for those 60 hours I was a task-completing machine. My focus at work was particularly sharpened and I came home and had the overwhelming urge to clean up and drop down for sets of push-ups between vacuuming each room. I also found myself shifting my mindset about what I am personally capable of. If I can function at a high level without food for nearly three days, why can’t I deadlift three times my bodyweight or brute-force my way up a few more rungs of the corporate ladder? The adaptability of the human body is amazing. Despite the common physical feeling of lethargy, research has shown that during the first week of fasting (yes, week) the body releases increased amounts of catecholamines and glucocorticoids, hormones that regulate our moods, immune response, and glucose metabolism. Those same flight-or-fight responses that can help keep us alive when we encounter a bear in the wilderness may also improve our mood, reflexes, and executive functioning for up to 168 hours without nutritional fuel. The same research also shows that fasting periods longer than a week do more harm than good in this context. For the record, I or any other health professional would not recommend you test these boundaries.
I became sleep deprived.
But it wasn’t all sunshine and roses. Much more apparent than a physical desire for food were disruptions in sleep. On the final night of fasting, I awoke at 3:30 am and couldn’t get back to sleep. This had nothing to do with a physical desire to raid my fridge (however, it created the perfect opportunity to get down a few thousand words before the wife and kids woke up). Interestingly, a change in sleeping habits while fasting is not unique. Research into the sleeping patterns of Muslims during Ramadan (a month of intermittent fasting in commemoration of Muhammad’s first revelations) has found all kinds of fascinating things, specifically a reduction in sleep latency and rapid eye movement sleep. Hardly a coincidence that my circadian rhythms were thrown off enough to induce me into waking during what should have been my final state of sleep. I had not previously noted any sleep disruptions with my normal routine. Having placed an increased focus on increasing my sleep hygiene as a means to improve overall health, this no doubt put some questions into my mind about future extended fasts.
I came out the other end of this personal vision quest alive, not feeling hungry, feeling great about my training progress and overall productivity, but (sadly) a little sleep deprived. Past the science of the possible health benefits (and risks), what I learned was that I am fully capable of doing whatever I put my mind to—for good or for bad. While I have no intentions of pushing my own satiety thresholds further and hope to make it abundantly clear that regular fasting is not for everyone, the experience has only strengthened my views about its benefits for me and I urge everybody interested in their own personal body and mind development to explore what works for them.
Dr. Damian Rodriguez is the health and exercise scientist for doTERRA International LLC. He holds a doctorate in health science, a master’s degree in exercise physiology, and countless professional certifications. He has spent most of his life researching nutrition, exercise, and the lifestyle behaviors associated with optimal health. Along with his passion for health, as someone who lives with Asperger’s Syndrome, he is also involved in bringing awareness to autism spectrum disorders. There are varying opinions about many health and fitness topics. His opinions are his own and not necessarily that of doTERRA International, LLC. Consult your healthcare provider before making any changes to diet and exercise.