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When circadian rhythm as discussed in the last entry is disrupted, negative changes can begin to take place in as little as a few days. After this short time, our genes begin receiving corrupt signals, resulting in compromised immunity that allows the onset of infections and other diseases, insomnia and cognitive/psychological malfunctions, migraines, diabetes, obesity, and even serious illness such as cardiovascular disease and/or cancer.

Throughout this series, you may see the term “shift worker,” so it is best to describe it before moving on: Salk Institute professor and founding executive member at the University of California in San Diego’s Center for Circadian Biology, Satchin Panda, a leading researcher into the science surrounding the circadian rhythm, defines it as someone who is awake more than three hours per night, more than fifty nights per year, between the hours of 10 p.m. and 5 a.m.[i] As we learn more about this vital, yet all-too-often disregarded mechanism, the more correlations surface between its disruption and serious physical and psychological health issues. In fact, night-shift work has become known to be a potential health hazard because of its ability to disrupt the circadian rhythm. Some experts now believe that heart disease is related to circadian rhythm. The link between interruption of the circadian rhythm and cancer has become so evident in studies of shift workers that “in 2007, the World Health Organization’s International Agency for Research on Cancer classified shift work as a potential carcinogen.”[ii]

Timing Food Intake

We mentioned previously that elements other than light can cue the circadian rhythm. Food intake is one of the largest factors negatively impacting our internal timekeepers, and its abuse does more damage than we realize. As previously said, when we eat matters as much as what we eat.

In 2009, an experiment was conducted wherein nocturnal mice were deprived of food during their normal eating hours (which would have been during the night), and instead were only fed during the day. Soon, it was revealed that “almost every liver gene that turns on and off within 24 hours completely tracked the food and ignored the timing of light exposure.”[iii] This means that while blue light is the most obvious trigger for the internal clock, food is capable of completely taking its place, causing “food to reset the liver clock, not the brain.”[iv] The body is able to take opposing cues from differing sources and adapt varying organs to function with independent timing. In other words, light tells our brains what segment of the cycle we’re are in, but food intake, when ill-timed (pun intended), communicates a different cycle to our organs, causing the system to fight against itself.

Because the cycle is inclined toward nutrition for the first segment of the day, our bodies enter physiological stages during the morning hours that set us up for optimal digestion and organ function. For example, morning light causes the brain and gut to communicate hunger signals to one another, priming the pancreas for insulin secretion. The muscles, which are preparing for manual labor, begin searching for incoming nutrition, and the body enters a type of “fat-storage” mode. (Don’t let this phrase intimidate you and don’t decline eating in the morning for fear of ruining your diet. The truth is, this is an optimal setting.) The science can seem complicated, but in a nutshell: When you eat, the body goes into a mode for storing fat, which it plans to subsequently turn into energy to carry you throughout the day. When you’re through eating and the body realizes no more food is coming, it switches into a “fat-burning” mode, wherein food just taken in is now used as energy. This conversion takes approximately two hours. Thus, nutrition taken in during the early portion of the day is temporarily stored as fat the body burns throughout the day. (Recall that the circadian rhythm has evolved over the centuries, and previous generations would have eaten breakfast and then done vast amounts of manual labor for the waking, daylight hours). As you go about your day, these calories are burned by activity, until sometime around midday, you get hungry again. The process of fat-storage/fat-burning repeats for the early and middle parts of the day, because these calories are stored in anticipation of the prime physical activity the body foresees for the upcoming afternoon.

After about eight to ten hours of food intake over the course of the day, the organs that process this influx begin to wind down and prepare for sleep. While the digestion process during the first part of the day can typically be completed within a couple of hours, after this time window, it takes significantly longer, because the gut and other digestive organs need rest. The consequence at this point is that the system, which “cannot make and break up body fat at the same time,”[v] is forced to store virtually all food intake as fat cells. As mentioned, food taken in and stored as fat begins to be burned after a couple hours, then the body switches from the fat storage setting to the burning setting. However, because the body is entering the sleep state and attempting to begin nightly detox processes, the fat-burning stage doesn’t engage until morning, when it is further confused by incoming nutrients and its self-determined position to instead switch into the storage mode. Thus, calories consumed at night become true manifestation of the old adage: “a moment on the lips, a lifetime on the hips.” Damage is caused to organs that must behave erratically just to find and maintain their place in a cycle that is being continually jarred by mixed signals.

This is why late-night snacking is devastating to our bodies. Since the pancreas, stomach, liver, and even muscles by this point are entering the pre-sleep mode while the body allows the blood pressure and temperature to spike as it begins to focus on an upcoming night of detox, these mixed signals confuse the organs. They were preparing for sleep, but now have to shift focus from the necessary routine activities to dealing with a sudden influx of unexpected (and uninvited) food. It throws their clock backward by several hours, launching them into a mode they would have been prepared for many hours earlier, but are not prepared for now. The timing is simply off.  Digestive juices are not secreted, and the liver, which was preparing itself for the night’s detox procedures, is occupied with other tasks. This launches the body into a type of emergency state to handle this unanticipated development. Other organs receive the message that intake is occurring, and, misunderstanding what hour of the day it is, they either speed up or slow way down in an attempt to re-sync themselves to the appropriate time. (Have you ever had a day that left you exhausted and hungry, but after you ate, you were unable to sleep? Bingo.) As all of these cogs within the wheel of the internal pacekeeper panic and autonomously attempt to assess and rectify their timing, the overall system is thrown out of whack. Additionally, because the body takes about two hours to switch from the “fat-storage” to “fat-burning” settings, sporadic eating keeps the body suspended in “fat-storage” mode for lack of opportunity to transition, causing everything we eat to be stored as fat. This impedes the ability of the pancreas to process and balance sugar and insulin levels, which leads to diabetes.[vi]

And we do this to ourselves every single night, don’t we?

Intermittent Fasting

The catastrophic impact of eating around the clock—as so many of us do—is cause for alarm, but there may be comfort for the reader in knowing that this problem has a very simple solution: intermittent fasting. Now, before you’re swept into the fear of the unknown, or the simpler but real terror of having to go hungry, hear us out. We’ve already hinted at intermittent fasting, but we’ll elaborated here. While some extremists may boast of their ability to fast for days on end, adding this practice to your everyday life can take on a much easier application. And, while some small sacrifice is still involved, the health benefits are literally immeasurable.

As a society, our eating habits have morphed over the decades. Whereas we used to eat three regular meals a day, we’ve added to this traditional eating style the model of snacking between every meal. In addition, the continual invasion of technology into our lives has resulted in a majority of people staying up much later in the evening hours than previous generations. These late-night indulgences are often accompanied with more munching. The result of this is that, by and large, we eat almost around the clock, and this is a workload our digestive organs were never designed for. As already explained, continual intake keeps a person’s body in the “fat storage” mode, but in addition, it overworks the gut, liver, and pancreas, which causes them to eventually wear out and even malfunction prematurely. (Imagine owning a car, but instead of turning it off when it’s parked, you always leave the vehicle idling, allowing no rest period. Eating around the clock places extra “miles” on vital tissues for no important purpose, and bring no fruitful yield in return.) Further, as stated, this nonstop influx greatly contributes to diabetes, impedes weight loss, and even impacts sleep. However, intermittent fasting can help reverse many of these cycles and set the body’s systems back into harmony. When we’re fasting, we spend more hours at a time in an uninterrupted, fat-burning state. Insulin levels decrease, causing the body to turn to stored fat for energy, which actually speeds up the ability to lose weight while giving such organs as the gut, liver, and pancreas time to rejuvenate between jobs, restoring efficacy to the entire metabolic function. Human growth hormone increases, which causes lean muscle to form, in turn promoting healthy caloric expulsion. Beyond this, the physiological changes that take place during a fast improve cognitive function and help reduce chances of such illness as cancer, blood pressure issues, and even ailments such as Alzheimer’s and Parkinson’s diseases.[vii]



Having already mentioned mitochondrial biogenesis, we won’t dwell on the subject here other than to recall the fact that intermittent fasting is one of the ways to initiate this cellular healing process.

The circadian clock and the timing of food intake directly impact the effectiveness of our metabolism and immune system and affects our inclination toward chronic illness, our cognitive function, and even our neurological health. As mentioned in the previous chapter, what we choose to engage in for the sake of our health can actually alter the condition of our cells and even change our genome. To learn more about this phenomenon, researchers came together from the University of California, the Baylor College of Medicine in Houston, Texas, and the Telethon Institute of Genetics and Medicine in Naples, Italy, to study the impact of feeding-pattern alteration on the genetic expression of mice. They found that intermittent fasting caused gene expression to incline toward prevention of aging, illness, and disease. The study revealed that “the reorganization of gene regulation by fasting could prime the genome to…anticipate upcoming food intake and thereby drive a new rhythmic cycle of gene expression… Therefore, optimal [intermittent] fasting…[could] positively affect cellular functions and…[benefit] health and…[prevent] aging-associated diseases.”[viii] (We’ll discuss how this is scientifically possible in the upcoming pages.)

Furthermore, the New England Journal of Medicine released an article in 2019, written by doctors Raphael de Cabo and Mark P. Patterson, which looked into the matter as well. The piece asserted that intermittent fasting initiates “adaptive cellular responses that are integrated between and within organs in a manner that improves glucose regulation, increases stress resistance, and suppresses inflammation.”[ix] Further, they stated that “preclinical studies show the robust disease-modifying efficacy…on a wide range of chronic disorders, including obesity, diabetes, cardiovascular disease, cancers, and neurodegenerative brain diseases.”[x] Other benefits were included in the report as well. Cellular fortitude in healthy cells was reinforced, creating better resistance to diseases such as cancer. Cognitive function saw improvements as it pertains to spatial, associative, and working memory, illustrating that fasting can be beneficial even to those who don’t believe they are struggling with chronic illness. Harmony between organs’ functions was restored, causing overall systemic efficacy to improve.[xi]


At this point, you may be wondering how it is possible that so many benefits can come from taking in minimal nutrients. The notion seems counterintuitive; after all, haven’t we always believed that eating nutritious food will arm our bodies to fight illness? How is it, then, that nutrient deprivation can drive our bodies toward myriad healthy, rejuvenating processes?

When we don’t eat for a period of time, the lack of food initiates a process called autophagy. The word, literally meaning “self-eating,”[xii] describes the survival mechanism by which the body begins to forage within itself for dead cells that it can consume as an alternative to incoming nutrition. This is the physiological response to the realization that food has been restricted. The system shifts into a type of survival mode, increasing efficiency by scavenging throughout its own system in search for material that can be eaten, reabsorbed, and recreated into new energy.[xiii] The best part of this process is that as it seeks out old or damaged cells and recycles them, the body likewise releases newer, healthier cells to replace them. Because his response is activated by self-scavenging, it prioritizes the weakest, most damaged, or degenerate cells.

A similar way to look at this process is if you were to suddenly be required to downsize your wardrobe, and were told that there is no guarantee of when new clothing will be available. You would operate with the realization that you must make careful choices as to what to keep or discard, understanding that this new, smaller wardrobe may have to last a while. Clothing that is worn out, torn, faded, threadbare, or otherwise close to its expiration will likely be thrown out first, while you’ll probably hold on to newer or better items. After your effort, you would have fewer items of clothing, but you would also have a wardrobe that is, overall, in better condition. In the same way, autophagy looks discriminately through the system for cells that are more useful to the body when burned as fuel than left as living cells, thus prioritizing those that are degenerate or unhealthy to be consumed. After a length of time in this process, you will have fewer degenerate and nutrient-leeching cells; you will have lost weight; and you will find that scrutiny of the remaining cells shows them to be in generally better condition.

Autophagy relieves inflammation, restores the immune system, contributes to insulin balance, and prevents and fights chronic illness. Not only does this process have beneficial detox properties, but this continual rejuvenation of cellular health alters gene expression, restoring health and delaying or even reversing the aging process.

Before a Fast

When the body is given food, its sense of threat is diminished; thus, all cells are nourished—even those that aren’t healthy. At the cellular level, communication pathways called mTORs (mammalian target of rapamycin), send signals regarding insulin and incoming nutrients.[xiv] In a fed state, these have proteins that keep the division and growth (reproduction) of these cells occurring regularly. (This process is the opposite of autophagy, mentioned previously, which is the recycling of dead or degenerate cells.) When mTOR pathways are overstimulated for long periods, they show a correlation to cancer cell development.[xv] When this part of the cellular makeup is in production mode (well-fed state), they have the power to disable the parts of the genome that efficiently facilitate fat metabolism, healing and reparation, inflammation, and even stress management.[xvi] However, during a fast, they have the potential to be reversed: the well-fed status of mTORs is switched to the nutrient-deprived state, while genes yielding benefits just mentioned are switched back on, a reversal process that is partially facilitated by ketones (agents created by the liver to balance insulin when food intake is diminished for a period; more on this later). This reversal is instigated by the AMPK (activated protein kinase) pathways—signaling units that alert the activation of self-preservation extremes. Via this transfer of orders on a cellular level, the body engages its response to threat: self-preserving mechanisms are triggered that increase the body’s efficacy with existing nutrients; foster an alternate, self-made form of insulin (ketones); and release resources designed to help the system operate with diminished sensations of stress despite increasingly worrying circumstances (lack of incoming nutrients). As AMPK orders are followed throughout the physiology, mTOR’s growth, division, and reproduction orders are ceased in favor of autophagy, mitochondrial biogenesis, antioxidant processes, cell repair and rejuvenation, fat breakdown, and use of general resources.[xvii]

UP NEXT: What Happened When Jesus Fasted?



[i] Panda, Satchin. The Circadian Code. (New York: Penguin Random House LLC, 2018), Pg. 6.

[ii] Ibid.

[iii] Ibid., Pg. 37.

[iv] Ibid.

[v] Ibid., Pg. 40.

[vi] Ibid., Pg. 41.

[vii] De Cabo, Rafael & Matson, Mark. “Effects of Intermittent Fasting on Health, Aging, and Disease.” The New England Journal of Medicine Online. December 26, 2019. Retrieved March 4, 2020.

[viii] Kinouchi, Kenichiro; Magnan, Christophe; Ceglia, Nicholas, et. al. “Fasting Imparts a Switch to Alternative Daily Pathways in Liver and Muscle.” Cell Reports. December 18, 2019. 3299-3314. Retrieved on March 4, 2020.

[ix] De Cabo & Matson, “Effects of Intermittent Fasting,” Retrieved March 4, 2020.

[x] Ibid.

[xi] Ibid.

[xii] English, Nick. “Autophagy: The Real Way to Cleanse Your Body. Greatist Online. July 1, 2019. Retrieved March 4, 2020.

[xiii] Wu, Suzanne. “Fasting Triggers Stem Cell Regeneration of Damaged, Old Immune System.” USC News Online. June 5, 2014. Retrieved April 24, 2020.

[xiv] Jarreau, Paige. “The 5 Stages of Intermittent Fasting.” LifeApps Online. February 26, 2019. Retrieved April 24, 2020.

[xv] Ibid.

[xvi] Ibid.

[xvii] Ibid.

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