Fasting for gut repair may seem like an odd idea, but research supports that fasting has widespread benefits for the whole body. The gut is included!
For example, people sometimes feel their best when they were fasting in preparation for a procedure. They aren’t eating during this time period at all.
Is it the fasting itself or the break from eating typical American foods?
After dabbling in fasting myself for quite a while, I feel it’s time to start talking about fasting for gut repair.
By the way, fasting truly helps people feel better too. I’ll get into why this is true.
There are many kinds of fasting. But the most common type of fasting these days is intermittent fasting.
By the way, you intermittently fast every day, whether you know it or not.
That is if you sleep (let’s hope you do!)
When you eat after this rest, it is called breaking the fast. Did you know that this is where the term breakfast came from?
Intermittent fasting is the easiest type of fast to follow. With intermittent fasting, you can simply eat dinner at a reasonable time. Then you eat a late breakfast the next day.
Research shows that intermittent fasting is safe for most everyone. After all, you really shouldn’t be eating a bunch at bedtime anyways.
The goal for most people is to have a 16-hour fast followed by an 8-hour eating window.
Prolonged fasts are more narrow eating windows or water fasts. In fact, some people go several days without eating during their fasts.
It’s important to take baby steps, though. And make sure to check with your doctor if you plan to do any type of prolonged fasting.
Related post: The Power of Fasting for Health + Side Effects
Fasting for gut repair-early research
Way back in the 1980s exciting research traction began to show that fasting helps to repair the gut.
For example, a small group of people with rheumatoid arthritis had tests on their gut permeability before and after fasting.
Not surprisingly, fasting reduced intestinal permeability according to this study.
In essence, this means that fasting helps heal their leaky guts. They also have fewer rheumatoid arthritis symptoms when fasting [R].
After eating a normal diet, rheumatoid arthritis symptoms returned.
Interestingly, another small study found the same results in the 1990s [R].
Fasting for microbiome benefits
Fast forward to the year 2021: new research shows that fasting definitely changes the microbiome by increasing beneficial bacteria.
Ramadan fasting results in increases in types of bacteria that are generally considered protective. This includes an increase in Akkermansia muciniphila and Bacteroides fragilis [R].
Intermittent fasting also enriches the microbiome diversity in the gut [R].
And, there are countless animal studies that show the benefits of fasting for improving the microbiome diversity and numbers.
Prolonged fasting helps with irritable bowel syndrome symptoms too [R].
One additional benefit that fasting may have on gut health is that it may increase bile production. Specifically, a type of bile is increased that is neuroprotective called tauroursodeoxycholate (TUDCA) [R].
Fasting may also improve gut muscle movements of the migratory motor complex. This is a cyclic pattern in the body that is disrupted by eating [R].
In this way, fasting may help improve normal bowel movement patterns and improve the microbiome too.
Heal the gut with fasting
Benefits of fasting for gut health are becoming more clear because fasting helps with cellular cleanup in the gut.
This cleansing process is called autophagy. By helping to improve cellular autophagy and function, fasting may help to improve the interaction of the immune system with intestinal pathogens.
In other words, the process of fasting, resulting in autophagy, likely helps to regulate immunity by helping to balance the gut microbiome [R].
While fasting, the body also increases the production of gut-healing fats called short-chain fatty acids too [R].
Ketones used to be a bit of a mystery, but new research shows that they have wide benefits for health. They promote nerve regeneration and improved cellular energy.
The type of body fuel, known as ketones, is usually produced on a ketogenic diet or during starvation.
However, you don’t have to follow a ketogenic diet or starve in order for the body to make ketones.
Time-restricted eating helps to increase ketones in the body. Why is this important for gut health?
Types of ketones like beta-hydroxybutyrate, while fasting, are increased in the morning. This ketone helps to reduce free radicals and oxidative stress in the body [R].
These helpful compounds also are used as a fuel source for colon and gut cells too [R].
Yet another way that fasting may help heal the gut is that it increases a beneficial compound called brain-derived neurotrophic factor (BDNF) [R].
This compound is known to do many beneficial things in the body. One role it plays is that it reduces intestinal permeability by decreasing a protein called zonulin occludin. Zonulin occludin is a protein that contributes to a leaky gut [R].
BDNF, by the way, also helps to promote neuronal growth, which is part of why healing the gut is critical for brain health.
May reduce cortisol
While research is a little bit all over the map related to the stress response and fasting, what we do know is that when people eat after fasting, their cortisol levels tend to drop.
Dropping cortisol is a good thing because it is the stress hormone. Having a lot of cortisol can cause harmful effects in the body if it is high for long periods of time.
Here is what the research shows:
- If you skip breakfast, odds are, your cortisol will drop in the morning. And, as you might expect, if you fast in the evening, your cortisol levels may drop in the evening [R].
- During a fast, cortisol levels can actually increase temporarily [R].
- Cortisol levels are lower after eating when morning-time fasting [R].
- In contrast, other research shows that Ramadan fasting doesn’t change cortisol levels [R].
Obviously, more research is needed to fine-tune the effects of fasting on cortisol.
For example, does the duration of fasting change cortisol?
Does the food you eat after a fast change how the body responds to fasting?
No doubt it does.
Improves circadian rhythm
Intermittent fasting and gut health are also connected because of the positive effects that fasting may have on your sleep cycle.
By improving your circadian rhythm, your sleep patterns also often improve, which is restorative to the whole body including the gut.
Increases anti-aging genes
A gene called SIRT1 is increased by fasting, which helps to protect the body from oxidative stress and protects your DNA from damage. SIRT1 gene is also is linked to increased lifespan.
Genes like SIRT1 help reduce aging and are increased by fasting.
SIRT1 genes play a major role in protecting against aging diseases like diabetes, heart disease, bowel diseases, cancer, and neurodegenerative diseases. This is because they turn on proteins that help to recycle damaged cells [R].
Not surprisingly, fasting may also help people with inflammatory bowel diseases such as Crohn’s and ulcerative colitis.
As you may recall, fasting helps people feel better with rheumatoid arthritis, an autoimmune condition. Other autoimmune conditions like celiac disease and inflammatory bowel disease may also be greatly helped by fasting.
People with celiac disease often only partially recover from a gluten-free diet. Adding intermittent fasting into the mix may help.
Celiac disease and other inflammatory gut diseases may benefit from fasting because it helps lower inflammation.
The inflammatory compounds that it reduces include, tumor necrosis factor-a, interleukin 6, and interleukin 1b [R].
By increasing anti-inflammatory compounds too, like adiponectin, fasting is likely helpful for inflammation everywhere in the body [R].
Helps cellular function
When people fast, they have an increase in proteins in their bodies called sirtuins. These proteins help to improve the function of our cells’ energy processes [R].
The gut is no exception.
Sirtuins (SIRT) proteins are linked to reduced rates of cancer, diabetes, and premature aging [R].
May reduce bloating and gas
Although no research has been conducted to confirm that fasting reduces bloating and gas, many people who fast find that this is true.
It could be that belly bloating is reduced because inflammation is reduced. Additionally, improvements in bile acids are happening due to fasting.
Or perhaps the body makes more digestive enzymes due to decreased inflammation and improved microbiome.
After all, the microbiome is critical for making digestive enzymes too [R].
May help fight infections
Do you know that most people’s appetite sharply declines when they have an infection? There may be a biological explanation for this.
Early research shows that fasting may help fight gut infections such as Salmonella. This is because fasting reduces the growth of Salmonella in the gut. It also helps prevent invasion of this harmful bacteria into the gut lining according to research in mice [R].
While it is still too soon to know if this works in people, fasting likely helps reduce bad bacteria.
Other fasting benefits
Not only do people use fasting to heal digestive problems, but there are also many research-backed benefits.
The majority of research finds positive benefits of fasting. Additional benefits people are often rewarded with are [R]:
- Weight loss
- Improved blood sugar
- Reduced insulin levels
- Reduced inflammation
- Reduced abdominal fat
- Reduced blood pressure
A fast is much easier than a complicated meal plan for fat burning too. Most people can easily fit it into their lives without much issue.
Improved mind-body connection also takes place for many people who fast.
This is because you eat when your body is truly hungry and needs fuel.
Let’s face it: most people eat because it’s time to eat, not necessarily because their bodies are truly hungry. By promoting eating when you are truly hungry, fasting helps people tune in to their bodies better.
At least this is true from my experience and the people I know who fast.
Fasting helps foods taste better too. After all, if you haven’t eaten in a while, you will appreciate your food more.
Tools for success
Many people experience that white-knuckle hunger, fatigue, or headaches when they first try to fast.
Don’t worry: over time, this gets better and there are things you can do to make fasting surprisingly pleasant and reap many digestive system benefits.
Sip on tea: herbal tea is a great way to hydrate and stay calm during a fast.
It’s ok to have just a little bit of calories
During a fast, you can have up to 50 calories without disrupting the benefits, so you can even put a little bit of cream in your tea and coffee and still maintain a fast.
Adding in a good electrolyte drink can really help reduce these negative symptoms of fasting and help you be successful during a fast.
After all, you lose electrolytes during a fast and may truly need to keep them in your routine.
Another tip to help is that you shouldn’t fast on a day where you have a family gathering, a party, or where fitting a fast into your day doesn’t make sense.
This could be when you are feeling sick or having premenstrual syndrome. It’s important to listen to your body and not push it too far.
The point of fasting is that it should work into your life, not the other way around.
When you do eat, make nourishing foods the ones you turn to. In this way, you will get healthy compounds for your gut that will further benefit you.
Research shows that breakfast eaters are healthier overall. However, this may be an artifact of social norms. Still, it’s probably best to eat breakfast and fast later in the day.
Regardless of the timing of fasting, what you eat during the eating time is probably still extremely important. A gut healing diet is recommended.
Try bone broth
Some people are more successful with fasting if they sip on bone broth a few times a day.
No research has been conducted about this method, but since bone broth is rich in amino acids and gut-healing minerals, it couldn’t hurt to try it.
Fasting for gut repair verdict
Long used for healing, fasting to heal digestive problems is experiencing a renaissance. After all, people have fasted since the dawn of time for religious and health reasons.
Part of the reason that fasting helps with gut health is that it may give the body a rest from processed foods and junk food. But, there is more to the story, as you can see.
Intermittent fasting increases antioxidants, healthy bacteria, and sirtuin proteins that may help with almost every aspect of health.
By reducing inflammation, promoting gut healing, and improving cellular function, fasting for gut repair is a simple tool that almost anyone can try for improving their health.
Who should avoid fasting?
It’s important to recognize that while fasting is helpful for many people, there are limitations to this approach.
If you are malnourished or very underweight, you should avoid fasting.
Also, pregnant women or breastfeeding women shouldn’t fast because the babies need a constant supply of nutrients.
When you have trouble with hypoglycemia or have type 1 diabetes, fasting isn’t recommended unless under the direct supervision of your doctor.
Always seek out the advice of your healthcare provider before embarking on any type of fast.
Heidi Moretti, MS, RD is The Healthy RD. A registered dietitian for 20 years, has a passion for functional nutrition and natural medicine. Has researched supplements and plants as medicine throughout her career. Loves helping people gain function and vitality by tackling the root causes of illness.
The information on this website has not been evaluated by the Food & Drug Administration or any other medical body and is shared for educational purposes only. While The Healthy RD’s posts are backed by research, you are unique, so you must seek care from your own dietitian or healthcare provider. This post is not meant to diagnose or treat any conditions. Consult your doctor or healthcare provider before making changes to your supplement regimen or lifestyle.