Last Updated on April 12, 2024 by Fasting Planet
While the novel coronavirus or COVID-19 has dominated much of the year, that’s far from the only virus we have to worry about. Each and every day, we may encounter upwards of 60,000 germs. Not all can cause illness, but the ones that do can leave you down and out in a hurry, with some even possibly causing death. Is it possible to fight and even kill viruses through intermittent fasting?
Fasting may kill some viruses outright, but not all. It can also help your health in several ways. By reducing or ceasing food consumption, you don’t feed viruses sugar, which they thrive on. You can also bolster your immune system and produce healthier cells through autophagy when on an intermittent fast, both of which can positively contribute to your health.
In this in-depth article, we’ll take a closer look at viruses and what causes them, which viruses we have to worry about, and whether intermittent fasting can rid our bodies of these. We’ll also discuss whether it’s ever smart and safe to fast when sick.
What Is a Virus?
We know that viruses can make us ill, but it’s so much more complex than that. What exactly is a virus?
These agents of infection need an organism with living cells to replicate. The organisms can include animals and people, yes, but microorganisms and plants as well. As the virus gets into the body, it changes metabolic processes to introduce more viral particles. This can happen through replication of the host cell or even by infecting our DNA.
Viruses on their own are not alive, but they can act as if they are once they reach your body’s cells. Despite that they don’t really live, per se, they do have a purpose, and that’s to keep making more viral cells. Reproduction allows the virus to spread, and not just across your body, but to those you come into contact with.
That’s not the only way a virus can spread, either. If an insect gets infected and bites or stings a person, that person could end up with a virus. The same is true of consuming water or food that’s contaminated with the virus, having sexual contact with someone with the virus (some viruses, not all), touching someone with the virus, and exposing yourself to their phlegm or spittle from sneezing and/or coughing.
Sometimes, spreading a virus is as simple as touching a surface a recently sick person used. Depending on the virus in question, it could live on surfaces for hours and even days.
Viruses are not the same as bacterial infections, although the two can manifest in much the same way. Bacteria have a different biological structure than viruses. They also don’t need a host to reproduce. Although bacteria can cause illness, they’re for the most part good for us. Some give us the nutrients we need for survival, others can combat cancer cells, more help with our digestion, and some can even fight microbes that could cause disease.
Even certain viruses are beneficial for our health. For example, some of our internal virus cells can combat Escherichia coli, more commonly referred to as E.coli, a bacteria that can lead to major health issues and even death.
Which Viruses Can Cause Illness in Humans?
There are countless viruses that affect humans. We can’t possibly cover them all, so we’ll give an overview of some of the bigger ones here.
- Hepatitis A virus: The hepatitis A virus can lead to a case of hepatitis, which causes symptoms like fever, lack of appetite, stomach pain, nausea, and fatigue. If you’re in close contact with someone who has hepatitis A or you consume contaminated water or food, you could develop this viral infection.
- Human immunodeficiency virus: The human immunodeficiency virus or HIV is caused by infected fluids, including sexual fluids and blood. The virus can progress to AIDS, which can be fatal without anti-retroviral therapy.
- Dengue virus: The condition known as dengue fever is spread by the dengue virus. Mosquito transmission is the most common spread, but if a mother has it, she can pass it along to her child. Symptoms include aches, rash, vomiting, and nausea.
- Hepatitis B virus: Like hepatitis A is caused by a virus, the same is true of hepatitis B. This can progress to a liver infection that can cause severe liver damage. Other symptoms include dark-colored urine, stomach pain, and yellowing eyes.
- Influenza virus: Type A through D influenza viruses can lead to that winter bout of sickness you experience every year. You may have symptoms like exhaustion, headaches, a runny nose, congestion, cough, achy muscles, chills, and a fever.
- Ebola virus: Another viral infection that can be caused by blood contact, Ebola leads to body chills, muscle aches, headaches, and fever. In more severe cases, a patient can begin coughing or vomiting blood, which can worsen internal bleeding. Organ failure and death are also possible.
- Epstein-Barr virus: Once referred to as Human gammaherpesvirus 4, Epstein-Barr virus is a herpesvirus, of which there are eight others. Mononucleosis can be caused by the Epstein-Barr virus.
- Coronavirus: COVID-19 is a novel coronavirus, but there are many others. Most have caused outbreaks, such as severe acute respiratory syndrome or SARS.
Does Fasting Kill Viruses?
Now that you understand more about viruses, let’s get back to our main question here. Is it possible to kill viruses with intermittent fasting?
Siim Land, a trusted resource for fasting and dieting, explored this very question in a video on YouTube. Between his video and other studies and data done on the topic, let’s look at how intermittent fasting can benefit your health and whether that may help you avoid viral infections or even kill preexisting ones.
Feeding Viruses
There’s an old saying that you’re supposed to starve a fever and feed a cold. What that means is you should eat less when riding out a fever and eat more to get through a cold. Both the cold and flu are considered incurable, in that you have to rest and wait recover, although medications may lessen their duration.
Okay, so does the old adage work? Do you really starve a fever and feed a cold? A 2016 article in Stat, a news resource, cites a study that tested the premise on mice. All mice were sick, but some had food and others did not.
If the mice were suffering from the flu, most who didn’t eat died. Only 10 percent of the mice lived. Those that were made to eat and even force-fed lived, with over 75 percent of the mice surviving.
As for the mice with a bacterial infection, if they didn’t eat, over 50 percent of them lived. If these mice were fed, within 10 days, they all died.
It seems then that the opposite is true then, that you should feed a flu and starve a cold. That said, what you eat during your illness matters a lot. Both viruses and bacteria love sugar, as it provides energy. If you reach for the sweet comfort foods while sick with a viral or bacterial infection, you could help the illness last even longer, even without meaning to.
On an intermittent fast, you’re either eliminating or reducing what you eat. Water fasts, where you subsist on nothing but water, are one such example of a restrictive intermittent fast. Some fasters follow the 16:8 method, where you fast for 16 hours and eat for eight. The alternate-day fast is appealing to beginners since you go only 24 hours without food and then you can eat the next 24 hours.
If you limited or even eschewed sugary foods from your diet, then both viruses and bacteria have nothing to eat. This could limit their survival, potentially leading to their death. At the very least, you shouldn’t have a large viral spread since the virus theoretically wouldn’t have the energy to reproduce.
Bolstering Your Immune System
In our many posts on intermittent fasting, one of the benefits that’s come up again and again is how fasting can help your immune system. That’s especially important in warding off viruses (and even bacteria).
Think of your immune system like the bouncer to a club. It’s supposed to notice invaders like viruses and kick them out.
That only happens when your immune system is in optimal health. If it’s not performing at its best, then these foreign invaders can sneak by and infect your system, causing mild and even serious illnesses.
One of the most-cited studies done on intermittent fasting for immune system health was published by Cell Stem Cell in 2014. It was proven that fasting for three days lessened the amount of white blood cells in the body.
This may not sound good, but it ultimately is. These white blood cells or lymphocytes strengthen the immune system. Like any cell though, they can weaken and even die with time. White blood cells tend to survive in our body for 13 to 20 days, so a little under three weeks.
When our body makes new lymphocytes through intermittent fasting, our immune system is ready to fight off foreign invaders like viruses even better than before.
There are some caveats to this study. The results were only proven with water fasting, so any other type of intermittent fast may not rejuvenate your immune system in quite the same way. Also, you need to do a prolonged fast lasting three days for best results.
Triggering Autophagy
The reason these new white blood cells could be generated is due to a process called autophagy. If you’ve missed our posts about autophagy, this internal process involves our bodies eating old or damaged cells, paving the way for healthier cells.
Intermittent fasting and a low-carb keto diet are two useful means of kickstarting autophagy. With fewer calories to use as energy, the cells in your body begin working more efficiently. They will then remove anything deemed extraneous, including damaged cells.
Can autophagy rid your body of viral cells? It can, but it may go both ways. This is something we’ve discussed on the blog, how autophagy can sometimes cause cancer cells to replicate. In a 2018 study published in Frontiers in Cell and Developmental Biology, researchers found that “selective autophagy has been reported to control several human viral infections in vitro, leading to the clearance of pathogens or viral antigens and host cell survival.”
The study also mentions that our cells need pathogen-associated molecular patterns or PAMPs for cellular immunity. These PAMPS allow for the creation of antiviral cytokines. Through autophagy, PAMPS reach receptor cells and could make inflammatory cytokines.
Inflammation can be both good and bad. In some instances, like the above, inflammation triggers the immune system into responding. That means it could fight off viruses earlier, possibly before you get too sick.
Activating Hormesis
Besides autophagy and a stronger immune system, it’s also possible that intermittent fasting may keep you healthier through yet another internal process. This is called hormesis.
In a 2008 publication of Ageing Research Reviews, the researchers defined hormesis as “a term used by toxicologists to refer to a biphasic dose response to an environmental agent characterized by a low dose stimulation or beneficial effect and a high dose inhibitory or toxic effect.”
In layman’s terms, hormesis occurs when stressors or even toxins push our organisms and cells into a multi-phased response. Siim Land talks about hormesis in his video, mentioning how hormesis can “make the body stronger in the future” by “strengthening all parameters of the immune response.”
He goes on to say the following: “fasting or not eating are physiological stressors that in the right amounts will strengthen the entire body.” This too could keep you healthy from viral infections.
The Verdict
A 2016 study published in the American Journal of Cancer Research sheds some light on whether fasting can kill viruses. The data found that fasting for 24-hour periods could cause oncolytic herpes simplex viruses to replicate. Again, on the surface, this sounds bad, but it isn’t. These viruses could lead to the death of cancer cells.
To reiterate what we said in the intro then, while it’s possible for intermittent fasting to kill some viruses, this doesn’t work for all.
You may be wondering, what about COVID-19, the novel coronavirus? The disease itself is COVID-19, while the virus that causes it is SARS-COV-2. Like other viruses, a healthy, strong immune system is a great defense. Should you go on an intermittent fast to boost your immune system and avoid getting COVID-19?
Dr. Peter Attia shares his thoughts in a YouTube video you can watch here. He says that while there may be a link between warding off the SARS-COV-2 virus through intermittent fasting, there’s no data proving as much. Attia also mentions that advocating for such a solution would be “irresponsible” on his part.
Besides, a healthy immune system may not be the only predicting factor in who does or doesn’t get COVID-19. The most serious cases involve those with underlying health conditions.
You need to stay as healthy as possible to avoid COVID-19. That means staying indoors, practicing social distancing, and intermittent fasting if you want. However, it’s not a miracle cure by any means, and no one’s quite sure what it’s impact could be on the virus.
How to Fast to Kill Viruses
You’d like to try an intermittent fast to kill a virus. As we said before, there’s no guarantee of that happening, but at the very least, you will bolster your immune system so it can keep you healthier in the future.
Here’s how to get started.
Choose a Type of Intermittent Fast
When fasting for killing viruses, certain types of intermittent fasts are better than others. Remember, you don’t want to feed the virus sugar, so juice fasts are out. Alternate-day fasts and 16:8 fasts can work, but you’d have to eat very nutritiously and low-carb. This will help you enter autophagy faster.
To make your body produce more white blood cells, water fasting seems to work best. We recently wrote a very informative post about water fasting if you want to learn more. Since your system may already be stressed from illness, we recommend a soft water fast over a hard one. This allows you to bathe, wash your hands, brush your teeth, and otherwise use water for non-drinking, hygienic purposes.
The duration of your fast is also important. A two-to-three-day fast may be necessary for an immune system overhaul when water fasting. To enter a state of autophagy, you may have to fast for 24 hours or longer, so plan for a lengthy period of not eating.
Get Your Doctor’s Approval
Before the fasting period begins, you want to run the idea by your doctor. Since you’re feeling under the weather anyway, a doctor’s appointment is a good idea. They may recommend a prescription medication that can lessen how long you’ll be sick or at the very least help with your symptoms.
If they think intermittent fasting can help you feel better, then you can soon begin.
Prepare Your Diet
First-time intermittent fasters really need to ready their bodies for what’s to come. With all intermittent fasts, you want to begin curtailing the quantity of food you eat. You might first shrink portion sizes, then go from three meals a day to two and even one.
If you’ll be on a mostly liquid diet, such as a water fast, then switching to smoothies or fruit and vegetable juices will put your body in the right shape to endure several days of water consumption.
Fast
The day of your fast has come, and you’re ready to get started. If you are indeed ill, then this is one instance in which we’d caution you against exercising. In healthy fasters, a bit of physical activity can trigger more fat burning and preserve muscle mass.
Since you’re not feeling well, don’t push yourself. Intermittent fasting can already cause mental fog and fatigue. Dealing with those side effects when sick can be hard, so rest as much as you can.
Reintroduce a Diet Post-Fast
When your fasting period is up, it’s time to slowly reintegrate your normal diet back into your life. If you’re sick, there’s a good possibility you might not be as hungry as usual. This is due to cytokines. While certain cytokines can cause inflammation in the body, they can also influence your appetite and your energy levels when ill.
Start with very small quantities of food. You’re supposed to eat at least every two hours, but you may stretch it to four hours. It’s fine to start with mostly liquids and work your way back to solid foods, even if you didn’t just complete a water fast. Just make sure you’re putting something in your system every few hours.
Can You Fast if You’re Already Sick?
Is fasting when ill even a good idea, or should you wait until you’re better? Let’s explore this question in more depth now.
A 2016 article in YaleNews talked about data discovered by a Yale research team with Ruslan Medzhitov, an immunologist, at the helm. Medzhitov stated: “when animals are infected they stop eating and they switch to a fasting metabolic mode…The question was whether fasting metabolism is protective or detrimental.”
You may recall that study done on the mice that we discussed earlier. To refresh your memory, by feeding the mice when they had a bacterial infection, they died. However, feeding mice with a flu may have helped their survival rate.
The Yale research team did something similar. Their mice didn’t only eat sugar, but protein and fat as well. The same thing happened to the mice, where the ones with the bacterial infections died but the virus-infected mice lived. The researchers also noted that fat and protein had no role on survival, but glucose or sugar did.
The team then got new mice and repeated the experiment, but with one critical change. Now, mice were fed a chemical that inhibited glucose metabolism. Interestingly, the mice with the viral infections did not survive in this instance while those with the bacterial infection did.
Medzhitov summarized: “During a viral infection, eating provides glucose, which may be necessary for survival.”
The fasting metabolic mode that animals go into exists for a reason. In people, it’s called infection-induced anorexia. A classic study in the journal Appetite calls this form of anorexia “a behavior systematically organized for pathogen elimination.”
The Dangers of Fasting While Sick
If you are sick and you’re permitted to go on an intermittent fast, make sure you watch out for some dangerous side effects. We recommend ceasing the fast and contacting your doctor immediately if you experience these symptoms.
Dizziness
Your illness may already make you feel woozy. Restricting your body of glucose, its prime energy source, can prolong and worsen that feeling. Do make sure your dizziness is not accompanied by blurry vision, concentration issues, fainting, and/or nausea. You could have hypoglycemia, which is a very low drop in blood pressure.
Dehydration
Every type of intermittent fast except hard dry water fasts allow you to consume fluids. Water is the most acceptable beverage, but black coffee and even some teas are your other options.
When you’re sick, it’s especially important you maintain your fluid levels, keeping these high. Each time you cough or blow your nose, releasing mucus, you lose some electrolytes. You can restore these through sports drinks, juice, or water…well, unless you’re fasting. Then you have fewer options.
In some instances, dehydration has been known to play a role on blood pressure, inducing hypoglycemia. That’s a great reason to stay hydrated. Another is that in the most serious cases, dehydration can be fatal.
Nausea
It doesn’t happen often, but some intermittent fasters have had nausea. If intense hunger can make you feel a little ill, then there’s a possibility you could have this fasting nausea as well. Should your illness cause nausea on top of that, you could be doubled-over near the toilet about to be sick.
We’d recommend eating something to reduce some of the nausea, thus breaking your fast.
Headaches
Depleting your body of glucose through an intermittent fast can sometimes leave you with a sore head. So too can all that coughing and sneezing when you’re sick. If your headache is really persistent, or if it evolves into a migraine, it’s a good idea to put the brakes on your fast until a later date.
Can You Take Medication on a Fast?
Another way to combat your illness besides intermittent fasting is to take the prescription medication your doctor gave you. Does that interfere with an intermittent fast or break the rules in any way?
According to Marie Curie.org, the type of medication you take plays a big role in whether it’s allowed. The site lists the rules for Ramadan, a Muslim observance that calls for strict fasting. Under Ramadan rules, eyedrops, eardrops, patches, and injections do not count as breaking the fast.
However, medication ingested orally would effectively stop the fast. This could interrupt your body’s autophagy. You have to think about your health in these situations and make a decision that’s best for you. Ask your doctor what your options are when fasting for illness and trying to take medication.
Conclusion
Intermittent fasting could kill some viruses, but not every single one by far. Even still, fasting to prevent illness can help in many ways. Your body eats damaged cells during a fast through autophagy, and water fasting could strengthen your immune system.
If you do decide to go on a fast when ill, you have to take extra precautions since you’re already not feeling well. Be aware of side effects and know when to stop the fast. Best of luck and stay healthy!