9 Benefits of Prolonged Water Fasting
1) Improves Biomarkers Associated with Aging
Whether or not prolonged fasting in humans increases life span is not entirely clear. However, fasting has been shown to improve biomarkers associated with aging and significantly extend the lifespan of mice.
A study found that a 5-day fast can activate longevity genes called SIRT1 and SIRT3.
When we fast, a complementary effect occurs where NAD+ levels increase, and hormonal effectors such as insulin, IGF1, and GH decrease, stimulating the binding of SIRT1 and SIRT3 to NAD+. The subsequent increase in sirtuins (SIRT1 and SIRT3) can positively alter longevity pathways such as DNA repair and telomere maintenance.
Interesting Fact
Part of the reason NAD+, NMN, and resveratrol supplements have gained much attention is because of the role of NAD+ on sirtuins. However, NAD+ activation and its downstream effects occur at a catabolic state (negative energy balance), meaning if you take NAD+, NMN, or a resveratrol supplement in a fed state, you might not get the same impactful longevity benefits. That said, NAD+, NMN, and resveratrol can potentially enhance a shorter fast if taken within the fasting window.
2) Improves Brain Function
Over two millenniums ago, Hippocrates wrote that fasting is a therapeutic intervention for epilepsy. Now, we know that ketones (an alternative fuel) that increase during fasting or through a ketogenic diet can reduce seizures by 50% in about half of children afflicted by epilepsy. We also know that fasting increases the expression of BDNF and FGF-2, which are important components for preserving and developing the brain.
Studies have shown fasting for 48 hrs can increase BDNF by 3.5 fold in muscle tissue. BDNF is a potent molecule that modulates neuropeptides and neurotransmitters and plays an essential role in synaptic plasticity (the ability of the brain to change in response to a stimulus), neurogenesis (the formation of new neurons), and neuronal stress resistance. BDNF increases the brain’s capacity to be more fluid by binding to TrkB receptors and altering neuronal excitability.
FGF-2, a molecule in the brain, kidney, and cartilage, promotes endothelial and neural stem cell integrity and angiogenesis and may encourage tissue or stem cell repair or growth. Moreover, stem cells generate new neurons that are important for cognition. However, to what degree and significance FGF-2 plays in cognition during or after prolonged fasting is not well understood.
Interesting Fact
Olive oil, green tea, dark chocolate, and blueberries can also increase BDNF. This is mainly why they are repeatedly advertised as brain foods. An acute bout of exercise can momentarily increase BDNF threefold, almost as much as a 48-hour fast.
3) Protects Against Cancer
Every year there are nearly 10 million cancer deaths, and fasting for five days has been shown to decrease chemotherapy-related toxicity and tumor growth. In advancing quality of life, many initially start fasting for its promising effects on lowering cancer risk. A period of food abstinence prompts these anti-cancer effects through a process known as autophagy and apoptosis.
In our body, there are trillions of cells that, over time, produce unwanted molecules that can cause cancer. Autophagy is the process of breaking down redundant or damaged molecules in the cell and reusing them for building and cellular repair. By definition, when we fast, our cells become starved of external nutrients. In this state, AMPK, an enzyme that plays a role in cellular energy, becomes more expressed and contributes to autophagy activation by inhibiting MTORC1 (a significant regulator of animal growth activated by food).
Additionally, sometimes the cells are weak, damaged, cancerous, or virus infected, and instead of cleaning up the inside of the cell needs a way of eliminating these types of cells. That is when apoptosis steps in. Apoptosis is the process of condensing, disassembling, and fragmenting all the intracellular content with minimal damage to the underlying tissue. During prolonged fasting, the body becomes better at identifying and targeting these cells by activating the perforin/granzyme pathway, which helps create channels around the cell for self-destruction.
Interesting Fact
Autophagy and apoptosis are present all the time but to a minor degree. What initiates these mechanisms further is often a form of physical stress such as fasting. Those who fast mainly to activate autophagy or apoptosis should therefore consider implementing another form of physical stress, exercise. By both fasting and exercising, you could potentially enhance autophagy more and maybe even get the benefits of a four to five-day fast in just 72 hours.
4) Protects the Heart
There is much conflict between heart health and cardiovascular disease. It was first presumed in this sort of a, b, c fashion that saturated fat leads to high LDL, elevated plasma cholesterol, and eventually cardiovascular disease. However, this concept brought up by Ancel Keys has largely been refuted. Now, meta-analysis suggests little to no association between high saturated fat and heart disease. New theories have sprung into existence (Dr. Rhonda Patrick) that instead, it's endotoxin released from the gut that binds to the cholesterol, which doesn’t allow cholesterol to go back into the liver that causes cardiovascular disease. This signals the immune cells to release proinflammatory cytokines to kill the endotoxin but can’t. So, instead, more are recruited and bound to this particle creating small dense LDL, eventually leading to a plaque.
A study published in the European Journal of Nutrition found that prolonged fasting reduces VLDL, VLDL cholesterol, LDL, and LDL subclasses. Not only does fasting reduce these markers, but by depriving your gut of sugar, you may restore healthy gut microbiome function and repair damaged mucin caused by insulin resistance at the gut level.
Moreover, fasting was found to increase nitric oxide, a powerful molecule “that helps blood vessels relax and also improve circulation” (Debra Fulghum Bruce), while also decreasing blood pressure and ADMA, a naturally occurring chemical that increases the risk factor for heart disease.
Interesting Fact
Organic meat such as beef and fish contains the highest concentration of Coq10, an antioxidant that can increase nitric oxide and even prevent migraines.
5) Decreases Chronic Inflammation
While acute inflammation is an immediate and temporary immune response to inflammation, chronic inflammation can lead to chronic inflammatory diseases, including diabetes, heart disease, and cancer. Earlier it was mentioned how fasting inhibits oxidative stress or a reactive chemical called ROS that could cause damage and lead to inflammation. But fasting could also decrease chronic inflammation through another pathway.
B-hydroxybutyrate (BHB), the most abundant ketone in the body, may directly inhibit NLRP3, a set of proteins called the inflammasome. The inflammasome drives proinflammatory cytokines IL-1B and IL-18 in response to infection or cellular damage. An over-activation of NLRP3 inflammasome and the subsequent chronic pro-inflammatory response has been linked to many diseases such as diabetes, Alzheimer’s, and atherosclerosis.
Not only does fasting directly decrease inflammation through B-hydroxybutyrate, but in this way, it may more appropriately have an opportunity to repair the body and improve the immune system. A study found that on surface injuries such as a burn, fasting before the injury can accelerate the healing of the injury more than not fasting. This finding may highlight why those who fast or calorically restrict reduce acne and tend to have cleaner-looking skin.
Interesting Fact
B-hydroxybutyrate could also be elevated with a ketogenic diet. People try this diet to lose weight, feel in control, and enhance mental clarity. Many of these effects could be from changes in gene expression, reduced inflammation, and BHB.
A ketogenic diet outside a clinical setting is generally followed by consuming around 70% fat, 20% protein, and 10% carbs. However, these numbers may vary depending on experience and exercise. And often, there is an unpleasant adaptive period resulting from a shift from high carb to high fat.
6) Reduces Anxiety and Stress
In the initial 48 hrs of fasting, anxiety, and stress could be increased for multiple reasons, such as increased cortisol, hunger, and a decrease in blood glucose. Which makes me wonder, how does fasting reduce anxiety and stress if it could cause it? The difference is that fasting increases stress momentarily.
However, fasting could reduce day-to-day stress and anxiety by decreasing oxidative stress and a pro-inflammatory cytokine (IL-lB) associated with anxiety and stress.
But what is oxidative stress? Oxidative stress is an imbalance between reactive chemicals called ROS and antioxidants. An overabundance of ROS can cause broken-down cell tissue and DNA damage leading to inflammation. Early signs of this phenomenon can manifest as fatigue, brain fog, decreased eyesight, and even memory loss. Fasting inhibits oxidative stress by increasing antioxidant protection and preserving mitochondrial function.
Now that we know more about oxidative stress, what is IL-LB? IL-IB is a pro-inflammatory cytokine involved in pain, inflammation, autoimmune conditions, and anxiety. A single dose of IL-1B in the brain caused anxiety in mice by controlling GABA synapses in the striatum. GABA is a neurotransmitter that decreases activity in the nervous system and has been associated with calming effects.
Interesting Fact
Taking endogenous antioxidants such as vitamins C and E is often looked down upon when taking fasting seriously. This is because these vitamins are presumed to work more as an aid and decrease the hormetic effects of the fast. In other words, vitamin C might relieve your body by allowing it to do a little less work or deprive your body of the opportunity to do a little more work. Whichever way you want to look at it.
7) May help with Depression
It is estimated that over 280 million people worldwide have depression, and many more people will experience a form of depression at some point in their lives. “Clinicians have found that fasting was frequently accompanied by an increased level of vigilance and a mood improvement, a subjective feeling of well-being, and sometimes of euphoria” (Guillaume Fond). Why this is the case is uncertain. However, many who fast claim to notice positive mood changes; for that, I will offer one explanation.
Have you ever decided to avoid all forms of unproductive stimulations for one week (YouTube, Tv, Social Media) while at the same time having a bout of minor depression?
Often, after the week is over, the depression seems to subside. Perhaps fasting works by momentarily depriving yourself of a positive stimulus (food) that sets you in a state that forces your body to rebalance itself. This rebalancing can occur on dopamine and inflammatory level. Research also shows that Inflammation and dopamine imbalance can be culprits in depression.
Interesting Fact
In 2022 Johns Hopkins Medicine Researchers found that two doses of psilocybin spaced two weeks apart under carefully controlled conditions can reduce major depressive disorder symptoms for up to a month after administration. Many studies also show similar findings, yet psilocybin and other forms of psychedelics are illegal in many places and are perhaps the most misunderstood drug.
8) Promotes Weight Loss
Not much needs to be said. If you completely abstain from food, your body will burn its energy stores. In the initial phases of the fast, the body will preferentially burn glycogen stores in your liver and muscle. Once the glycogen is depleted, the brain will signal to the body to burn fat through lipolysis while supporting glucose levels through gluconeogenesis, a process whereby glucose is made by other means, such as fat. Eventually, the longer you fast, the more stored fat you burn, but if you fast too long, the body may also start to use lean muscle tissue as a source of energy.
This effect of prolonged fasting on reduced muscle tissue may also be more pronounced in those who are lean and fit than obese. However, ketones that are elevated during prolonged fasting seem to help the muscles from not being excessively used as energy. I wouldn’t be too concerned about muscle loss for a 5-7 day fast unless you’re a competitive bodybuilder.
Interesting Fact
Taking 3 grams of an omega-3 supplement can increase resting metabolic rate by 5.3% in healthy adults. The resting metabolic rate accounts for how many calories you burn at rest: for men, that's about 1800 kcal, and for women, 1400 kcal. That means omega-3 intake could increase RMR by 70-100 kcal daily or 500-700 kcal weekly.
9) Improves Psychological Resilience
Resilience is managing and coping effectively with difficult or taxing situations. How well do you endure physical pain? How well do you tolerate emotional pain? I cover many ways to improve resilience in much greater detail in the article The Science and Psychology of Acquiring Resilience. I talk about stress in modifying and broadening our breadth for resilience. But in the continuation of this section, we will briefly touch on the brain since our capacity for coping with resilience is largely found in the complex architecture of this organ.
To test the relationship between emotional experience and resilience, 36 firefighters were recruited for a study. Then, the researchers provided trauma or relaxing scripts and tested their brain activity in an fMRI throughout the study. They found two things:
1) The orbitofrontal cortex was activated, an area of the brain important in the cognitive process of decision-making.
2) The area of the brain called the amygdala, essential for processing fearful and threatening stimuli, was also activated.
What’s even more fascinating is that the amygdala and the hippocampus, a complex brain structure for storing long-term information, can communicate with one another. This communication can bridge short-term interpretation to long-term memory and perception. When fasting, we activate and may even strengthen the communication between the amygdala, orbitofrontal cortex, and hippocampus. To put it differently, fasting may induce brain resilience.
Interesting Fact
The diet and psychological resilience can be intertwined. Often what is causing inflammation, gut distress, and lethargy is what we put into our mouth. What may appear to be a genetic lack of resilience is instead the result of the current state of our food choices.
Bottom Line
Prolonged fasting could be arduous on the body. The drastic change in chemicals, macromolecule utilization, and hormones could cause feelings of fatigue, lightheadedness, and irritability. If prone to these symptoms or have an underlying disease consult your doctor about fasting and do your research. Even if you don’t have an underlying condition or disease, starting with a shorter fast and working your way upwards might be best.
As of writing this, I am nearly five days into a 7-day water fast. I don’t feel bad. I'm not crawling to get from point a to b. Instead, I feel very much like my normal day-to-day self but without the usual stamina. Sure, there are cravings, and sometimes it isn’t pleasant. But the cravings that come and go are worth the tremendous benefits of a prolonged fast.
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