Last Updated on April 12, 2024 by Fasting Planet
Allergy season, cold and flu season. It seems like every time a new month arrives on the calendar, there’s some illness out there to worry about. You need a healthier immune system more than ever. Is fasting the way to better immune health?
Yes, fasting can improve your immune system. You don’t even need to go on a particularly lengthy fast; one that lasts at least three days can give your whole immune system a much-needed reset according to a California-based 2019 study.
If you’re interested in learning how fasting can have such a big impact on the immune system, you’re not going to want to miss this article. In it, we’ll delve more into what fasting does for the body, which viruses you may ward off through fasting, and how long to fast for a stronger immune system. Keep reading.
How Does Fasting Make Your Immune System Healthier?
We confirmed in the intro that yes, fasting can play a role in the health of your immune system. The question becomes how?
To answer that, let’s quickly go over the basics of fasting.
Your body has a supply of glucose that it gets from the foods you consume. As we’ve written about before, carbohydrates provide a lot of that glucose. When you go about your routine, the glucose gets burned off as energy, fueling everything you do.
The goal of fasting is to burn away all that glucose so your body begins burning fat instead. This can take hours or days depending on how often you fast and the supply of glucose you have.
As you torch body fat through fasting, you become trimmer and lose weight. Another benefit transpires at the same time. Burning all that fat causes your body to make more ketones. These ketone bodies are liver chemicals produced when you lack the insulin to make glucose into energy.
Beta-hydroxybutyrate or BHB is one ketone your body makes during this time. BHB is particularly noteworthy because of how it benefits your immune system.
In a 2015 study in the journal Nature Medicine, when Yale School of Medicine researchers studied immune system cells, those with more BHB caused less inflammation. This study was done on humans.
Another piece of data from 2014 in Cell Stem Cell found that damaged immune cells were recycled through fasting. This happened in both humans and mice.
As a reader of this blog, you should know what’s going on here. This is autophagy, where your body takes damaged and old cell parts (or the whole cell) and eats them so only healthy cells remain.
In your immune system especially, you want nothing but healthy cells. The white blood cells there include macrophages or monocytes, neutrophils, and lymphocytes such as NK cells, B-cells, and T-cells. Any of these white blood cells live for 13 to 20 days before the lymphatic system destroys them.
By continuing to regenerate new blood cells–and strong, healthy ones at that–through autophagy, your immune system can ward off the foreign invaders that make you sick.
Which Illnesses, Conditions, and Diseases Can Fasting Help Prevent?
You’re now aware that fasting triggers the production of healthy white blood cells and can control inflammation for a better immune system. Are there any conditions and diseases that fasting may be able to ward off?
Indeed, there are plenty, so let’s talk about these more now.
Flu
Influenza or the flu is a seasonal illness that can be deadly. It killed 29,000 to 59,000 people in the first half of 2020 according to CDC data as published in a Health.com article. The symptoms are far-ranging, causing nasal congestion and nose runniness, sweating, fever, lack of appetite, coughing, muscle pain, fatigue, and fever. Some people with flu also report lymph node swelling, a sore throat, breathing troubles, nausea, headache, and pressure in their chest.
The flu is viral, so it’s incurable. If you have it, the best thing to do is rest until you feel better, and get plenty of fluids. Stay away from others too so they don’t get sick.
If you remember from our article about fasting’s effect on viruses, we talked about the adage to “feed a cold and starve a fever.” That saying may have come about due to the lack of appetite we tend to feel when we’re sick with a virus like the flu.
In 2006, The Turkish Journal of Pediatrics talked about this very concept, which is likened to a type of anorexia. According to the study, our bodies trigger an acute phase response to a viral infection. This response includes the production of cytokines that make us feel less hungry.
“Locally released cytokines may inhibit feeding by activating peripheral sensory fibers directly or indirectly, and without a concomitant increase in circulating cytokines,” the study says. The signals go to our central nervous system in the brain to interrupt hunger cues and appetite.
The crux of the study is this: our bodies have held onto this evolutionary anorexia because it benefits us somehow. In the days when we had to hunt for our food, if we were sick, hunting would burn up most of our energy. This could inhibit our recovery, making it drag out longer.
If you don’t feel hungry, there’s no need to spend this precious energy looking for food. A classic study in Neuroscience & Biobehavioral Reviews also found that when our bodies are purposefully deprived of zinc, iron, and other nutrients, we can’t feed the virus further. This prevents it from spreading.
Cold
Most adults get the cold at least twice every year, says the CDC, with about three million annual cases in the US alone. The cold is much less serious than the flu, but it shares some of the same symptoms. These include congestion, sneezing, nose runniness, and even fever in some instances.
Like the flu, the best thing to do when you have a cold is ride it out until it’s over. It too is a viral infection, so while medication can lessen symptoms, it won’t treat the virus itself.
Given that adage to starve a fever and feed a cold, should you fast if you have a cold? Actually, with any viral condition, it’s better to eat, unless you’re in the acute phase of your illness. Then, it’s believed fasting can have a positive effect. Once you’re past that window, only bacterial infections benefit from being starved.
Cancer
Cancer includes a broad range of diseases, among them lymphoma, leukemia, lung cancer, colon cancer, melanoma, basal cell cancer, prostate cancer, breast cancer, and many more. Lots of studies, among them this 2011 report in Oncogene, have found that fasting reduces inflammation, lessens chemotherapy damage, and decreases one’s insulin resistance.
High Blood Pressure
If your blood pressure exceeds 140/90, then you have hypertension or high blood pressure. One’s diet, age, stress, and weight can play a role in their blood pressure. If yours is high, it’s important to bring it back down, as hypertension could cause stroke and/or heart disease.
A 2009 study from The American Journal of Clinical Nutrition reports that intermittent fasts can lessen triglycerides, total cholesterol, and body weight. By eliminating or reducing these risk factors, your blood pressure should come down so you’re less likely to have heart disease or stroke.
Type 2 Diabetes
Insulin resistance and lack of insulin production are two trademarks of type 2 diabetes. The condition leads to symptoms like blurry vision, exhaustion, hunger, feeling thirstier than usual, and urinating more. Some type 2 diabetics are asymptomatic.
This form of diabetes is incurable, but treatments like insulin therapy, medication, and a diet and exercise plan can help. Some diabetics have also found that intermittent fasting can improve insulin resistance.
Alzheimer’s
Alzheimer causes the degradation of brain cells and their connections, so the person’s memory begins to decrease. In the US, three million new cases of Alzheimer’s are diagnosed every year.
Lots of data, including this report from Ageing Research Reviews, have found that fasting may help the brain age better. It’s believed this can prevent the onset of Alzheimer’s. Not only that, but fasting can protect from Huntington’s and Parkinson’s diseases as well.
Is It Better to Do a Shorter or Longer Fast for Better Immunity?
You’d definitely like to go on a fast to toughen up your immune system, but how long should you abstain from food? Should you stick to a shorter, multiday intermittent fast or spend longer periods fasting?
Most data support that an intermittent fast is best here. A 2019 article from fitness resource FLOWIN cites a University of Southern California study that talks about how fasting can kickstart the production of new white blood cells. This can happen in two to four days according to the research.
Professor Valter Longo, the University of California Professor of Gerontology and the Biological Sciences likens these intermittent fasts to turning on “a regenerative switch.”
“It gives the ‘OK’ for stem cells to go ahead and begin proliferating and rebuild the entire system,” Longo says.
To come to this conclusion, a group of human participants fasted for six months in two-day or four-day increments. Therefore, it’s not enough to go on a single intermittent fast for a day or two and expect that your immune system is healthier for it.
The FLOWIN article mentions that your body makes less of the PKA enzyme through long-term intermittent fasting. Also known as protein kinase A, PKA may trigger the growth of tumors, leading to higher cancer risk. It also contributes to aging.
Knowing that, it makes sense to think then that a longer fast would be even more beneficial to your immune system, right? Not necessarily. A 2019 article from news site New Atlas talks about this very topic.
A study was done on fasting mice. The researchers divided the mice into two groups. One group fasted for under 24 hours while the second group fasted for at least 48 hours. Both groups of mice could ward off infection well enough after fasting. Their wound-healing abilities also weren’t inhibited.
However, the mice that fasted longer had altered immune responses. Your body’s immune response is the reaction to foreign invaders via fluids and cells. If this response is interrupted or weakened, then so too is your body’s ability to fight off foreign invaders. This will surely lead to increased rates of illnesses.
Yet another study cited in the New Atlas article is also worth discussing. It also used mice. The researchers wanted to see how the animal’s immune system reacted to fasting and whether a longer fast impacted immune response. All the mice used for the study were healthy and young.
When the mice had to fast for 36 hours or longer, their immune responses were indeed disrupted. Further, the mice had a stronger allergic response and more metabolic dysfunction.
Does this mean longer fasts can’t help your immune system? Not necessarily. First, the studies above were all done on mice, not people. While we humans may have similar reactions if put in the same conditions, until more testing and data proves as much, it’s all just conjecture for now.
The New Atlas article even says “what all this research means is that fasting diets may not be beneficial for everyone, and different kinds of fasting can result in drastically different kinds of immune system responses.”
Dr. Valter Longo and a colleague of his, Roberta Buono, Ph.D. were both requested for comment by the New Atlas team. They had this to say: “the…studies demonstrate the ability of different forms of fasting, as well as different lengths of fasting, to cause potent but distinct and at times opposite effects on the levels and function of various immune cell types, thus underlining the need to replace terms like fasting, or intermittent fasting, with those that describe the…length of the fasting method.”
Until there’s more concrete evidence, you may want to stick to shorter fasts for now, just because those are proven to be more effective for most study subjects. You can also consult with your doctor about which fasting length may be best for your health, age, and level of physical activity.
More Tips for Immune Health
Besides fasting for stronger immunity, what else can you do to help your immune system be at its healthiest? Here are some good habits to incorporate into your life.
Lessen Stress
There’s a lack of research on the effects of stress and your immune system. That’s because it’s difficult to quantify stress, as everyone reacts to stressors differently. Still, some data exists, and it’s enough for scientists and medical professionals to confirm that when you’re in a stressed state, your immune system may not be able to prevent antigens from causing infection and illness.
Whatever creates stress in your life, actively work to reduce it. Perhaps you meditate or get lost in a hobby to control stress. In doing so, your immune system will be better off.
Prevent Infections
Fasting may be effective in preventing the onset of illnesses and infections, but this doesn’t mean you shouldn’t actively care for your health. When cooking foods that could contain illness-causing bacteria, such as chicken, always wash your hands thoroughly. Make sure you cook the food through.
Wash your hands at other times as well, such as before eating, after going to the bathroom, and when coming home from being out.
Get Enough Sleep
An average adult should sleep for at least seven hours a night, with nine hours preferable. If you’re only skating by on five or six hours of sleep, it’s not enough. Your weaker immune system cannot fight off infections as effectively, which tends to get you sick more often.
Keep Your Weight Down
According to an article in Live Science, having extra abdominal fat affects our immune system’s abilities. The article also mentions that if an obese person drops at least 10 pounds, their immune health may improve.
Fasting is a great way to get your weight down and burn that excess stomach fat. In the periods you’re not fasting, make sure you’re eating a low-carb, nutritious diet. This will help you keep the weight off.
Get Exercise
Besides diet, physical activity is another benchmark of good health. If you can exercise when fasting, we recommend it, as it’s a good way to preserve muscle mass (fasting can sometimes burn muscle proteins with fat). Otherwise, get in some sweat sessions in between fasting windows.
Your enhanced circulation from exercise lets immune substances and cells travel through the body with more ease. Now they can get to foreign invaders immediately, cutting off threats before you ever feel a symptom.
Avoid Alcohol and Smoking
A 2015 study in Alcohol Research found that alcohol lessens your host defenses, which can in turn increase inflammation, infection rate, and the risk of developing illnesses and diseases. Smoking has a similar effect on your immune health.
You don’t have to cut out all alcohol from your life, but certainly drink in moderation. Also, although smoking is a hard habit to quit, it’s worth it for your immunity.
Conclusion
Fasting benefits your immune system by triggering the production of healthy new white blood cells. These can keep you safe from bacterial and viral illnesses as well as diseases like cancer, type 2 diabetes, and Alzheimer’s.
The next time you go on a fast, know that besides your waistline, you’re also helping your immune system!