Fasting And The Immune System | What’s The Connection?

The word “fasting” triggers panic. We all love food – giving it up is NOT a pleasant thought. However, receiving a cancer diagnosis might change your mind when it comes to fasting. Intermittent fasting, a form of fasting that implements time restrictions on when you eat, is a hot topic these days. Water fasting isn’t as popular, because obviously it’s too hard – it also isn’t sustainable. Let’s find out the connection between fasting and the immune system. 

Fasting And The Immune System - Glass Of Water

No one can dispute the benefits of fasting, such as better digestion and detoxification, increased mental clarity, and weight-loss. Not many people associate these benefits in regard to cancer and fortification of the immune system.

Fasting And The Immune System 

Never before in history has our environment been so toxic, with over 85,000 toxic chemicals being spewed into the environment. Our food and water supply is polluted with plastics, GMOs, heavy metals, EMFs, and pesticides. Medications factor into this, as well. From the time we wake up to the time we go to bed, we’re bombarded with a sea of toxins.

Why talk about toxins when it comes to the immune system? Because they are intricately connected – these toxins are damaging to our health, putting us at increased risk for autoimmunity, diabetes, heart disease and stroke.  We breathe in toxins, we eat and drink them, and we slather them on our skin.

Toxicity is causing us to be inflamed, exhausted, and to age at a faster rate than we otherwise would. Fasting promotes the removal of carcinogenic toxins and substances from the body.

Cancer cells, which are accustomed to metabolizing toxic waste from normal metabolic processes, can’t survive without fuel, causing them to eventually die.  In a fasted state, normal cells slow down and go into survival mode, whereas, cancer cells become stressed and die. 

Formation Of Free Radicals

Free radicals are highly reactive molecules produced by normal processes of metabolism. These reactive molecules are also the result of toxicity. Free radicals damage cells, and bind to cytokines, reducing immune function by damaging immune system pathways.

This decrease in immunity is a set-up for cancer and other diseases.  Fasting is a viable therapy due to the fact that normal cells behave differently than malignant cells when in a fasted state,. Fortunately, we can use this to our advantage.

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Inflammation And Immunity 

Fasting reduces inflammation. This reduction, not only aids in the prevention and treatment of cancer, but also prevents other chronic diseases which are epidemic. Inflammation is problematic because it’s a precursor to a myriad of dysfunctions in the body. There’s a direct correlation between inflammation, reduced immune function, and cancer.

Chemicals, as discussed above, promote inflammatory processes. Couple this with inflammation and cancer risk climbs. This connection is clearly seen in certain types of cancers, including esophageal, liver, colon, and pancreatic cancer, the latter being one of the most deadly cancers. For this reason, inflammatory diseases, such as colitis, hepatitis, and pancreatitis, are associated with greater cancer risk.

In chronic inflammatory states, immune cells produce reactive molecules that damage DNA and stimulate cell division, a distinguishing feature of cancer. Inflammation is like a low-grade fire that continually burns. This perfect storm of inflammation, DNA damage, and cell division can initiate the development of cancer.

When cells that have DNA damage divide, mutations are more likely to occur. In modern society, many people are living with chronic inflammation that has been going on for years and even decades. It’s not surprising that cancer rates have increased.  

What Are The Benefits Of Fasting?

Listen to Dr. Jason Fung’s:  “The Complete Guide to Fasting.” He talks about intermittent fasting, same day fasting and extended fasting.

Fasting And The Immune System - Pancakes With Red X On Them

Intermittent Fasting Guide

Intermittent fasting is a pattern of eating that reduces the window of food consumption. There are a variety of ways to implement intermittent fasting. I personally like the 16/8 method, where you confine your eating to an eight-hour window, fasting for 16 hours. Remember, half of that time includes the time you’re sleeping, so it’s not as hard as it sounds.

For me, intermittent fasting is the best of both worlds. I get the benefits of fasting, but still get to enjoy two meals a day, which is of course much more sustainable than regular fasting. Once you get used to it, intermittent fasting isn’t that difficult. Essentially, all you’re doing is not eating after dinner, and skipping breakfast in the morning.

As insulin levels decline, fasting gets easier. Elevated insulin levels cause inflammation, leading to blood-sugar and hormonal imbalances. High insulin can also produce cravings, making it harder to fast. It can take a few weeks to get your insulin levels down, depending on your degree of insulin resistance.

It’s essential to soldier through this time, remembering that it will get easier. Intermittent fasting is highly effective at improving your fat to muscle ratio, leading to a better body composition, better blood-sugar balance, increased insulin sensitivity, and reduced inflammation. This puts your body in a state of health that cancer can’t thrive in.

Insulin Resistance And Cancer

When cells becomes insulin resistant, due to chronically elevated blood sugar, glucose can’t enter the cell. This leads to high glucose levels in the bloodstream. Why is this significant? Because glucose fuels cancer growth and depresses the immune system. When blood-sugar levels are chronically high, a vicious cycle ensues, with the pancreas producing more and more insulin to lower blood sugar.

This is a dangerous situation because there is now more sugar in the bloodstream, which stimulates cancer and tumor growth. It gets worse. Cancer cells metabolize energy differently than normal cells do.

Malignant cells have been shown to have increased glycolysis, enabling them to use glucose as their primary fuel source. Glycolysis occurs in the cytoplasm of cancer cells, as opposed to the mitochondria in normal cells. This is why cancer is often viewed as a disease of the mitochondria.

Glycolysis And Lactic Acid

During glycolysis, cancer cells produce lactic acid, which shifts the blood to a lower pH, while increasing cell-multiplication. This acidic environment enables cancer cells to survive and thrive. Acidity also causes the cells to store more toxins, and toxins by nature, are acidic. Adding insult to injury, cells can’t dump toxins in an acidic environment, leading to further toxin build-up and acidity.

Oxygen levels are also reduced, providing the perfect environment for cancer to grow. When cells proliferate, they produce even more acid, leading to a cycle of cancer growth, acidity, and more growth. Cancer cells have up to ten times more insulin receptors than do normal cells, making them more receptive to insulin signaling, which can promote cancer growth.

Recently, studies have found that cancer cells may even produce and secrete their own insulin. The fact that cancer cells contain more insulin receptors is one reason Insulin Potentiation Therapy, a form of low-dose chemotherapy, is so effective, making it possible to differentiate cancer cells from normal ones.   Fasting And The Immune System -  Hydrogen Generator

Intermittent Fasting And Detoxification

Intermittent fasting is a great way to detoxify the body. When you eat, your body is in a building mode, which is not conducive to detoxification. Fasting, however, promotes detoxification and cleansing.

By extending this detoxification period, more toxins are able to be eliminated. Many people operate on a 14/10, or 12/12/ hour eating window, leaving little time for detoxification, causing a cascade of negative repercussions.

On the other hand, reducing your eating window, increasing the hours you fast, promotes healing, boosts immune function, and mitigates cancer risk. It’s critical to stay sufficiently hydrated when you’re fasting so toxins can be moved and excreted.

When fat cells are broken down in a fasted state, they release toxins. These toxins then need to be mobilized and eliminated.  If you don’t drink enough water, this doesn’t happen, and the toxins will be recirculated.

Intermittent fasting will also save you time and money. The time-saving factor is actually more significant than you’d think. Imagine how much time you could save every day by not having to buy, prepare, eat, and clean up one less meal. Every aspect of your health can be improved by intermittent fasting. 

Intermittent Fasting And Autophagy

The overarching reason intermittent fasting is so amazing for preventing cancer has to do with a process called autophagy. Autophagy is essentially cellular clean-up, where damaged cell parts are recycled and reused, toxins are disposed of, and repair mechanisms initiated.

 Autophagy is what allows the body to sustain metabolism during periods of fasting or starvation. Intermittent fasting stimulates autophagy by stressing the cells of the body. Autophagy prevents cancer by recognizing and removing rogue cells.

All cancers stem from cells that have become defective. Autophagy declines with age, leading to more cells that are diseased, dysfunctional or cancerous. Intermittent fasting, because of its ability to stimulate autophagy, can prevent cancer cells from potentially developing. It also frees up vital energy so the immune system can do its job more effectively.

Autophagy And Apoptosis

Is there a relationship between autophagy and apoptosis, a mechanism where unhealthy cells are programmed to die? While there is no clear evidence the two are related, it’s surmised that autophagy may be a mechanism behind this programmed-cell death. Eating, absorbing, digesting, and eliminating food requires a lot of metabolic energy.

This energy is no longer needed in a fasted state, enabling the immune system to better do its job of eliminating cells that could potentially become cancerous. Intermittent fasting is a profound way to heal your body. When used in conjunction with a Ketogenic diet, it’s alchemy. Most people can do at least some form of intermittent fasting, excluding cases of extreme exhaustion.

[Read More: “Keto For Dummies”]

Wet and Dry Fasting 

What Is Dry Fasting?

When most people think of fasting, they associate it with dry fasting, which is abstaining from both food and water. Wet fasting excludes food, but allows water. I’m not a proponent of dry fasting, particularly for cancer, because water is necessary to excrete toxins from the body. Dry fasting, also called absolute or black fasting, is used to enhance spirituality and enlightenment. 

Hard dry fasting, is taken to an extreme level, where absolutely no contact with water is allowed. This means no water when brushing your teeth and no showering. There are even retreats that foster this type of fasting.

Incidentally, when Jesus fasted for forty days in the wilderness, He did a wet fast. The longest documented dry fast, recorded in The Guinness Book of Records, is 18 days. However, keep in mind, dry fasting is not advised for longer than 24-36 hours.

Benefits Of Dry Fasting

Proponents of dry fasting use it for both acute and chronic degenerative diseases. It stimulates the immune system, purifies the blood, heals the mucosal lining in the GI tract, while activating anti-inflammatory mechanisms. Dry fasting also clears blockages in the blood vessels, eliminates pathogens, and regenerates healthy tissue. It’s similar to “survival of the fittest,” meaning only the healthiest cells survive when they’re deprived of food and water.

Compare this to unhealthy and diseased cells, which aren’t so fortunate. They are unable to survive extreme conditions, culminating in a process called autolysis. Autolysis, or self-digestion, happens when diseased tissues are destroyed through the action of their own enzymes. Interestingly, autolysis is seen postmortem.

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Key Points

Fasting is a critical aspect of cancer-prevention and therapy. Intermittent fasting, as opposed to wet fasting, can be engaged in long-term – it does involve a lifestyle change, but offers all the benefits of water fasting. Both are powerful techniques to detoxify the body, reduce insulin levels, balance hormones, prevent chronic disease, and strengthen immunity.

A robust immune system is what will ultimately enable your body to heal from cancer. If you or someone you love has cancer, please learn more about the benefits of fasting, and incorporate it into your cancer-healing protocol.

Would you consider fasting if you had cancer? Let me know in the comments:)



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(1) US National Library of Medicine National Institutes of Health: Fasting and cancer: molecular mechanisms and clinical application

(2) US National Library of Medicine National Institutes of Health: Fasting to enhance Cancer treatment in models: the next steps

(3) US National Library of Medicine National Institutes of Health: Effects of short-term fasting on cancer treatment

(4) US National Library of Medicine National Institutes of Health: Autophagy and intermittent fasting: the connection for cancer therapy?

(5) nature communications: Fasting inhibits aerobic glycolysis and proliferation in colorectal cancer via the Fdft1-mediated AKT/mTOR/HIF1α pathway suppression

(6) frontiers in Immunology: Targeting Glucose Metabolism to Enhance Immunotherapy: Emerging Evidence on Intermittent Fasting and Calorie Restriction Mimetics

(7) US National Library of Medicine National Institutes of Health: Fasting induces anti-Warburg effect that increases respiration but reduces ATP-synthesis to promote apoptosis in colon cancer models

(8) ANNUAL REVIEWS: Metabolic Effects of Intermittent Fasting

(9) ScienceDirect: Fasting-induced apoptosis in rat liver is blocked by cycloheximide

(10) healthline: Autophagy: What You Need to Know


  Disclaimer: “I am not a medical doctor, and therefore, cannot diagnose or treat any medical condition, nor do I claim in any way to cure disease. Please be diligent and always do your own research in regard to any material I present on this site. I claim no responsibility for any distress, whether it be physical or emotional, that may occur as a result of the information you obtain from my blog.”

8 thoughts on “Fasting And The Immune System | What’s The Connection?”

  1. Cancer is a very ugly condition and I hope the world finds a lasting solution to it. I actually lost two close relatives to cancer. I hope fasting does help reduce cancer in the body. But, I’m really looking at your fasting model and looking to implement it in my life. 16/8 is really not a big deal if it helps my body detoxify.

    Should I begin doing this everyday or once in a while?

    Expecting your feedback

    • Hi Louis,

      Cancer is on the rise and is a heartbreaking disease. I’m sorry for your loss.

      The 16/8 method is great to do just to feel and look better. I do it everyday, but you could do it every other day or just a couple times a week. Do what feels right for you!

      Thanks for reading and commenting!

  2. Hi!

    I have been doing intermittent fasting for about a month now and I definitely notice the benefits already! I feel the difference and it’s great to know this will help prevent cancer, since this tends to run in my family. I want to do everything I can to prevent getting it, even though it may not always be in our hands.

    I did not know about these benefits, but it makes me even more happy that I have decided to start doing IF.

    Thanks for the interesting read!


    • Hi Melanie,

      Good for you for implementing intermittent fasting into your lifestyle. I do it also and I really like how it makes me feel. I have more energy, my clothes fit better, and mentally I’m sharper. Plus, I know I’m preventing disease and reducing inflammation. 

      Intermittent fasting scares people but in reality it’s not that hard, especially once you get used to it. Thanks so much for reading and commenting!

  3. Hi there, So I was diagnosed with cancer and I would definitely consider fasting to help myself heal. I’m considering doing a longer fast then the daily intermediate fasting. How long of a fast would you recommend to begin with? A 24, 48 or 72 hour fast? Thoughts you can please share…

    Very Joyfully,

    • Hi Carmen,

      I’m sorry to hear about your diagnosis. If you haven’t already, I would start by intermittent fasting for two to four weeks before doing longer fasts. That way you can get your body used to going without food. After that, I would start with a 24-hour fast, and gradually increase from there. Best of luck to you!


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