In the past few years, intermittent fasting has become increasingly popular. Many nutritionists, doctors and personal trainers recommend fasting either as a type of therapy or as a change in lifestyle. Fasting is rooted deep within human history.
It’s difficult to pinpoint the exact time fasting started, as it developed as a natural survival instinct for many animals. During times of food scarcity, fasting became essential to human survival. Our ancestors practiced intermittent fasting as a way of life. In the past, people ate what they managed to hunt and gather. If food were not immediately available, they would fast, sometimes days on end, until a food source was found.
As time progressed, humans began to recognize the mental and physical benefits of periodic fasting. As time progressed, the health benefits of periodic became increasingly recognized. In ancient Greece and Egypt, fasting was prescribed to treat certain diseases, such as epilepsy. It was also used in the prevention of illness. Benjamin Franklin was spot on in his famous quote, “The best of all medicines are resting and fasting.”
Fasting has remained a vital part of every civilization, from both a spiritual and medicinal standpoint.
THE SAME ROUTINE PLAYS A SIGNIFICANT ROLE IN MANY RELIGIONS THROUGHOUT THE WORLD
Fasting was developed as a religious practice among different cultures, with fasting being central to many religions.
Muslims, during the holy month of Ramadan, fast between dawn and dusk.
Fasting was also viewed as a powerful prayer in both the Old and New Testament of the Bible. Christ insisted that fasting should be done humbly and privately, rather than publicizing a fast for display and accolades. This is exemplified in Matthew 6:16 NIV, “When you fast, do not look somber as the hypocrites do, for they disfigure their faces to show others they are fasting. Truly I tell you, they have received their reward in full.”
MANY PHYSICIANS IN HISTORY HAVE ADVOCATED FASTING FOR HEALTH BENEFITS
In the mid-1800s, Doctor E. H. Dewey, in his book The True Science of Livingmid-1800s wrote, “Every disease that afflicts mankind develops from more or less habitual eating in excess of the supply of gastric juices.”
Early great philosophers, such as Hippocrates, Plato, and Aristotle have all praised fasting. Hippocrates, one of the fathers of Western medicine said: “to eat when you are sick, is to feed your sickness.”
Fasting has also been recognized in the Bible for its positive effects on epileptic seizures. Many biblical scholars indicated people suffering from epilepsy could not be cured unless they engage in prayer and fasting. We now recognize a state of deep ketosis can assist with the control of epilepsy. Fasting allows for a more regular ketogenic state.
THE MECHANISM OF FASTING
When fasting, the body is allowed to cleanse itself and reach its optimal function levels.
Fasting influences some of the most critical health mechanisms of our body:
- The circadian rhythm
- The gut (also known as the second brain)
- Insulin sensitivity
THE CIRCADIAN RHYTHM
Humans during their evolution have developed a circadian clock to ensure that physiological processes are executed at optimal times. The circadian rhythm occurs across a 24-hour cycle and significantly affects our behavior.
Many gut functions, and almost every physiological and biochemical function in our body is affected by the circadian rhythm. Interrupting this rhythm can initiate a series of changes that can lead to obesity, diabetes, cancer, and cardiovascular diseases.
Intermittent fasting can help recover the circadian rhythm, as its main cues are feeding signals.
A study involving the implementation of a smartphone app to assist with eating patterns demonstrated a beneficial relationship with decreased evening eating and overnight fasting. Increasing overnight fasting to 14 hours resulted in improved sleep quality, reduced weight, and feeling more energetic. (1)
THE GUT
Intermittent fasting directly and positively influences the gut microbiome, also known as our second brain.
Research has shown that intermittent fasting directly reduces gut permeability and systematic inflammation, and improves gut integrity. Intermittent fasting has shown to increase the browning of white adipose tissue and to shift the gut microbiome in one that favors a lean metabolic profile as opposed to an obese phenotype. (2)
INSULIN SENSITIVITY
Intermittent fasting can modify our hormonal responses in many ways. However, the effect on insulin sensitivity is thought to contribute to many of the beneficial results found during intermittent fasting.
Insulin resistance is a condition where cells require increasing amounts of insulin to process glucose (sugar). In turn, the pancreas is required to produce increasing amounts of insulin to achieve the same response. Insulin resistance eventual leads to a variety of metabolic derangements. Its presence is central to a variety of diseases, including metabolic syndrome, polycystic ovarian syndrome (PCOS), cardiovascular disease, nonalcoholic fatty liver, and many more.
Doctor Jason Fung, a world-leading expert on intermittent fasting, said, “Resistance really depends on two things. It’s not simply the high levels, but it’s the persistence of those levels. What people have realized is that a period of time where you can get your insulin levels very low is going to break that resistance because it breaks that persistence. Not simply the levels, but the persistence of those levels.”(3)
Intermittent fasting lowers your insulin levels. This, in turn, allows the body to mobilize energy stores from the liver and peripheral fat, thus reducing the overall demand for insulin. A research study of adult men demonstrated significant improvements in insulin sensitivity while fasting(4). This has also been supported by another study published in The Journal of Nutritional Biochemistry(5).
FASTING IN MODERN CULTURE
Today, societies across the globe are increasingly recognizing the relationship between mind, body, and spirit, including the body’s ability for self-healing.
FASTING FOR WEIGHT LOSS
Intermittent fasting is hugely praised for its effectiveness for weight loss. It allows your body to access stored fats for energy use.
Glucose and ketones are both energy sources for the body. If glucose is available, the body will preferentially use this as a fuel source. Constant availability of glucose as the primary substrate limits the utilization of glycogen breakdown from the liver. This renders fat unavailable for utilization as a fuel source. The body is unable to process stored in any significant amount until glucose levels are decreased, thus signaling the liver to process glycogen, the lowering of insulin levels, which finally leads to the mobilization of fat. Fats are then converted into ketones, which are efficiently utilized by the brain, muscles, etc. The problem is, the body cannot burn both sugar and fat at the same time. The body will always select the easier route, which means it will burn sugar most of the time.
In reality, this leads to hormonal imbalance, weight gain, and water retention.
Doctor Taz Bhatia, the founder of CentreSpring MD, says, “I think many people don’t realize there is work involved when we are constantly eating food, or grazing, or snacking or drinking.”(6)
Fasting is a simple, yet effective method of adjusting your weight loss journey on the right path.
Decreasing glucose intake from highly processed carbohydrates and periodic fasting allow for increased insulin sensitivity, which has beneficial effects for the body as a whole. In addition to improved insulin sensitivity and metabolic profile, lower insulin levels allow for decreased water retention.
A win-win situation for weight loss: fat as an energy source, reduced water retention, and a reduction in chronic disease.
FASTING FOR BETTER MENTAL FUNCTIONS
According to Doctor Mark Mattson, a professor of Neurology at John Hopkins University, “fasting has been shown to increase rates of neurogenesis in the brain.” A study involving neurogenesis (the formation of new neurons) after ischemic stroke demonstrated a 30% increase in neuronal cell growth when fasting occurred compared to mice allowed to eat freely(7). While this model is an animal model, it is highly plausible that similar mechanisms are likely at work amongst our species.
Another study shows that fasting boosts production of BDNF by 50-400%. BDNF, which stands for brain-derived neurotrophic factor, is a protein that has a huge role in allowing the brain to change and adapt and makes it more stress-resilient(8).
According to Genetics Home Reference, “The BDNF gene provides instructions for making a protein found in the brain and spinal cord called brain-derived neurotrophic factor. This protein promotes the survival of nerve cells (neurons) by playing a role in the growth, maturation (differentiation), and maintenance of these cells. In the brain, the BDNF protein is active at the connections between nerve cells (synapses), where cell-to-cell communication occurs. The synapses can change and adapt over time in response to experience, a characteristic called synaptic plasticity. The BDNF protein helps regulate synaptic plasticity, which is important for learning and memory.”(9)
FASTING FOR PHYSICAL FITNESS
Fasting can significantly improve your overall fitness.
With intuitive eating, fasting is a central part. Once in tune with true hunger cues, as opposed to those resulting from boredom, stress, or habit, food consumption occurs with true hunger. This allows a natural period of gut rest to occur.
Even though many people believe that fasting negatively affects your metabolism, those beliefs are not supported.
If done correctly, fasting improves metabolism, promotes the utilization of stored fat, and allows efficiency in metabolic processes. It can also increase the endurance of people who are physically active.
In fitness, there is a term known as VO2 max, the maximum amount of oxygen per kilogram of the body, per minute, that your body uses during exercise. The higher your VO2 levels, the better you perform.
A study conducted on two groups, one who fasted overnight, and one who had breakfast an hour before. Their VO2 was then measured during a training session.
The group who fasted overnight had significantly better results, with a 9.7% increase in VO2 max levels, while the group who had breakfast had only 2.5% increase(10).
FASTING FOR MEDICINAL PURPOSES
Fasting is increasingly recognized for many benefits beyond weight loss.
IMPROVED CARDIOVASCULAR HEALTH
It also improves your overall cardiovascular health by lowering your cholesterol and triglycerides. A study conducted on 16 obese subjects has shown that 8 weeks of alternate fasting reduced LDL cholesterol by 25% and triglycerides by 32%(11).
Another study conducted on more than 4,000 people connected routine periodic fasting with a lower risk of coronary artery disease, as well as a considerably lower risk of diabetes(11).
INCREASES HGH
HGH (Human growth hormone) is a hormone vital for many health aspects, such as growth, metabolism, muscle strength and weight loss. Several studies have shown a significant increase in HGH levels after fasting for only 1-2 days.
In medicine, we tend to frown on “Ns of 1”, meaning using a single case as proof of an overall effect, whether it be positive or negative…. However, think Terry Crews. He stays “ripped” with intermittent fasting and lots of baby oil. (12)
PREVENTS CANCER AND INCREASES CHEMOTHERAPY
A study involving rodents demonstrated alternate-day fasting has helped in blocking the formation of tumors(13). A similar study found that cancer cells when exposed to several fasting cycles behave the same way as with chemotherapy. It delayed the tumor growth and increased chemotherapy effectiveness.
However, there are many still unanswered regarding the behavior of malignant cells, fasting, and autophagy. Some studies indicated that certain types of cancer cells can activate internal autophagy, thus protecting them from the therapeutic effects of chemotherapy(14). Further research is required to determine the applications of the ketogenic diet, autophagy, and the use of fasting as a therapeutic agent.
CONCLUSION
While the above references and topics are not an all-encompassing, perhaps our ancestors knew best. There are many reasons to fast!
REFERENCES
- Gill S, Panda S. A Smartphone App Reveals Erratic Diurnal Eating Patterns in Humans that Can Be Modulated for Health Benefits. Cell Metab. 2015;22(5):789-98.
- Li G, Xie C, Lu S, Nichols RG, Tian Y, Li L, et al. Intermittent Fasting Promotes White Adipose Browning and Decreases Obesity by Shaping the Gut Microbiota. Cell Metab. 2017;26(5):801.
- Asprey D. Why You Shouldn’t Fear Fasting with Dr. Jason Fung and Jimmy Moore – #367 [Available
from: https://blog.bulletproof.com/why-you-shouldnt-fear-fasting-with-dr-jason-fung-and-jimmy-moore/. - Halberg N, Henriksen M, Soderhamn N, Stallknecht B, Ploug T, Schjerling P, et al. Effect of intermittent fasting and refeeding on insulin action in healthy men. J Appl Physiol (1985). 2005;99(6):2128-36.
- Mattson MP, Wan R. Beneficial effects of intermittent fasting and caloric restriction on the cardiovascular and cerebrovascular systems. J Nutr Biochem. 2005;16(3):129-37.
- Galvin B. Can fasting help you lose weight? One doctor weighs in 2018 [Available from: http://www.fox5atlanta.com/health/fox-medical-team/can-fasting-help-you-lose-weight-one-doctor-weighs-in].
- Manzanero S, Erion JR, Santro T, Steyn FJ, Chen C, Arumugam TV, et al. Intermittent fasting attenuates increases in neurogenesis after ischemia and reperfusion and improves recovery. J Cereb Blood Flow Metab. 2014;34(5):897-905.
- Mattson MP, Duan W, Guo Z. Meal size and frequency affect neuronal plasticity and vulnerability to disease: cellular and molecular mechanisms. J Neurochem. 2003;84(3):417-31.
- Reference GH. BDNF gene.
- Stannard SR, Buckley AJ, Edge JA, Thompson MW. Adaptations to skeletal muscle with endurance exercise training in the acutely fed versus overnight-fasted state. J Sci Med Sport. 2010;13(4):465-9.
- Bhutani S, Klempel MC, Berger RA, Varady KA. Improvements in coronary heart disease risk indicators by alternate-day fasting involve adipose tissue modulations. Obesity (Silver Spring). 2010;18(11):2152-9.
- Williams B. Terry Crews’ Secret to Looking Ripped: Intermittent Fasting and Lots of Body Oil: Men’s Health; 2018 [Available
from: https://www.menshealth.com/fitness/a20771387/terry-crews-intermittent-fasting-workouts/]. - Rocha NS, Barbisan LF, de Oliveira ML, de Camargo JL. Effects of fasting and intermittent fasting on rat hepatocarcinogenesis induced by diethylnitrosamine. Teratog Carcinog Mutagen. 2002;22(2):129-38.
- Antunes F, Erustes AG, Costa AJ, Nascimento AC, Bincoletto C, Ureshino RP, et al. Autophagy and intermittent fasting: the connection for cancer therapy? Clinics (Sao Paulo). 2018;73(suppl 1):e814s.
DISCLAIMER: The advice on this page is not meant to replace or represent medical advice. This is nutritional advice, which is NOT the same as medical advice. Before any weight loss endeavor, the consultation of an experienced health care provider is a must. As a general rule, the following individuals should not participate in fasting:
- Diabetics-particularly those on insulin
- Lactating women
- Pregnant women
- Individuals with a history of eating disorders
- Children under the age of 18
This list is not
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