Maybe you have thought about sickness and fasting and wondered if it would help you in that condition. Living in Switzerland, I’m used to colder temperatures that can make me more prone to sickness. I was looking for ways to reduce how much I get sick when I came upon the topic of fasting against sickness and started to research if it would be effective. This is what I found….

Fasting offers benefits like fighting bacterial infection, strengthening your immune system and lowering your inflammatory response. However, don’t force fasting on the body if you feel hungry. Listen to what your body says. If the body says hungry, then eat. 

How Fasting Affects the Immune System

Some believe that fasting can reset the immune system. While a one-day fast won’t have a strong effect, some studies have shown how a three-day fast can reset the body’s immune system. 

The USC conducted a study that found how drinking only water for three days with less than 200 calories per day truly could reset your body’s immune system. 

First, they researched rats, but they kept a level of healthy skepticism knowing how a rat responds may be different from how humans respond to fasting when sick. In both cases, researchers found that fasting lowered your white blood cell count. 

The lower white blood cell count may look like a bad thing, but what happens next suggests otherwise. Once this would happen, it triggers the immune system in the body to generate new white blood cells. 

Valter Longo, one of the researchers behind the study, believes that this may happen because the body is forced to recycle the unneeded immune cells. 

That explains why the body drops in its white blood cells, and once you eat again, the body boosts the immune system to replenish the white blood cells that were recycled.

You should, however, note that the results from the study are preliminary, which means that they take place before a more serious study. We can’t call this conclusive evidence, but it does seem to suggest that it could help. 

What Does Resetting the Immune System Mean?

Let’s put this into perspective on what the resetting of the immune system means. Resetting the body’s immune system strengthens the whole body. 

It will ward off viral and bacterial infections easier. You will see healthier and stronger white blood cells produced as a result. 

Researchers have found how fasting resets the immune system even in the elderly. 

Another Thing That Fasting Does

After a one to two-day fast, the body starts to burn through your glucose and fat stores. You wind up with a byproduct known as ketones as the body breaks down stored fats. 

Some evidence suggests that increased ketone production leads to the following benefits:

• Improved brain health
• Support for endurance training
• Better fat-burning capabilities

Ketones serve as a preferred source of energy for the body and the brain. We must highlight how none of this is conclusive evidence, but research does show a possible link. 

One of the most beneficial ketones that fasting produces is known as the beta-hydroxybutyrate (BHB), which benefits the body’s immune system. 

One study from Yale University found how the BHB levels after two days of fasting would reduce the body’s inflammatory response. 

Inflammation happens as a natural process when the body tries to heal and defend itself from some foreign attacking agent. Reduced inflammatory response means less swelling, pain and heat. 

Fasting Lowers Insulin Levels? 

Diabetics have especially found a problem when they get sick because their insulin levels shoot out of control due to the hormones released during sickness. 

Even minor sickness can raise their blood sugar to dangerously high levels and make it hard to lower. 

Fasting has been shown to reduce insulin levels, according to this article from Healthline. That may prove beneficial to those with diabetes, but people should consult with their doctor ahead of time. 

The research out there shows that fasting reduces insulin resistance, which is one of the things that cause diabetes. 

High levels of insulin in the body can also suppress T cell production, which are meant to prevent inflammation. 

T cells are a type of white blood cell that work with macrophages, but unlike macrophages, they can attack invading cells and viruses, which means that having more T cells from lower insulin levels due to intermittent fasting will help with fighting off illness. 

What Does the Science Say About Fasting for Sickness?

You have hundreds of studies on animals doing intermittent fasting and a few on humans that show how intermittent fasting may help with health conditions like diabetes, obesity, cancers and neurological disorders, but it would be a mistake to take this as conclusive evidence. 

The studies that were done for fasting against the common flu and such things have been scarce. 

We don’t want this article to mislead people, and it would be wise to consult with your doctor before you undertake an intermittent fast against sickness. 

Some evidence suggests that a three-day fast can reset your immune system, which would help with sickness, but more studies must be conducted to prove this theory. 

You may want to simply listen to your body and what it tells you when sick. If it says to fast intermittently, then do it. Otherwise, eat when it says to eat. You don’t have to eat when you don’t feel hungry, however. 

What is the Theory of Why Fasting Works against Sickness?

The main theory that researchers have behind why fasting works is that it concentrates all of the body’s energies on fighting infection. Instead of having to split its attention on turning food into energy, the body can focus entirely on healing. 

Nothing has been proven, but that’s the theory behind it. Even if fasting does have its benefits, don’t force it on the body when sick since this could have a negative effect. 

Many studies are being conducted on the topic and no one knows for sure either way. 

How Could Fasting Help to Cure a Cold or Flu?

Much evidence exists to suggest that fasting could help to fight bacterial infections and food may help to fight viral infections.

Colds and cases of the flu can be caused by either viruses or bacteria. Influenza and rhinovirus are the most common culprits, and when they attack the body, they can lower your immune system so that a bacterial infection can enter. 

Many people when sick don’t feel hungry, and in fact, they may even cringe at the thought of food. The body may be doing this to initiate the immune system’s response and fight off the infection. 

Looking at this from a survival perspective, when not hungry, you don’t have to go out and hunt for food. That reduces heat loss so that your body can concentrate its efforts on healing. 

One of the theories behind this is that the lack of appetite encourages the body to fight off the infected cells using a process called apoptosis. 

Another way that they call it is cell suicide, which also protects the body from intracellular parasites. Restricting your nutrients can begin the process of apoptosis, and the body may try to stop your hunger as a way of promoting apoptosis. 

Animals Fast When Sick 

It may be worth noting how animals fast when they’re sick. They lose the urge to eat. This may come from an instinctive knowledge that it will help to fight off the bacterial infection. 

Whenever an animal suffers an injury or illness, you often find it hard to get them to eat. This may help them to devote all the body’s energies to healing over spending it on digestion. 

As a first instinct, many animals when sick will abstain from eating. Cats and dogs have both been observed doing this behavior.  

What Foods Should You Eat When Sick?

First, we would recommend that you stay hydrated when sick since vomiting and diarrhea can cause dehydration. Drink lots of water. 

The Mayo Clinic recommends that you stay hydrated with plain water, warm lemon water with honey or clear broth. Avoid things like caffeine and alcohol since they can dehydrate you. 

Green tea is another great choice to stay hydrated because it promotes the production of B-cell antibodies. This helps the body to fight off invading pathogens. 

Some foods may prove more beneficial when sick than others, such as:

• Honey—a powerful cough suppressant and has antibacterial and antimicrobial properties. 
• Garlic can lessen infections since it is known as an antibiotic.
• Chicken soup is full of vitamins, minerals, calories and protein. 
• Coconut water to rehydrate and possibly control blood sugar.
• Elderberries have many phytonutrients and antiviral properties.
• Ginger can stop nausea and inflammation.
• Broccoli—known as a superfood and nutrient powerhouse—may fight off the flu.
• Avocados are a rich source of vitamins, minerals, nutrients—they’re also another superfood that tastes great! 

Some of these foods have proven a benefit at least in terms of being healthier for people, and they can help in cases where the body feels sick. 

I would like to end this with a concoction that I drink myself when I feel sick:

• 1 cup of green tea
• Light lemon juice for taste
• 2 tablespoons of liquid artisanal flower honey (beware of buying from the supermarket since it’s liquid sugar)
• 1 cm of ginger cut to bits

You will take the drink and mix it before making it hot. Along with it being healthy, it tastes good and you can drink as much as you would like. 

Related Questions

Why do I feel sick when fasting? Intermittent fasting could make you feel sick, and depending on the length of the fast, people have experienced headaches, lethargy, irritability and constipation. This could be due to what they call a keto flu, which happens when the body switches from food intake to fat stores—the sickness suggests that it’s struggling to do it. 

Does fasting increase immunity? A growing body of evidence suggests that a three-day fast may help to reset the body’s immune system. However, research on this remains inconclusive and further studies will need to be conducted to know for sure.