A Guide To Intermittent Fasting To Heal Your Gut

Intermittent fasting (IF) is a diet plan in which you eat during a strict eating window — often 4-8 hours each day. Also called time-restricted eating, this flexible diet has many different eating schedules to fit your needs, and its benefits include vast improvements to your gut health.

I often find an unhealthy gut as the underlying cause of my patient’s hard-to-treat health problems through my telehealth functional medicine clinic. Many of my patients have tried almost everything to heal their gut or their overall well-being, including supplements, bone broth fasts, and elimination diets.

It’s not until they come to me that they consider intermittent fasting as an effective tool to heal their unbalanced microbiome.

While IF has a wide variety of well-known health benefits, its gut health benefits are often overlooked. When you fast, you are giving your gut a much-needed rest—a point I cover in depth in my book, Intuitive Fasting: The Flexible Four-Week Intermittent Fasting Plan.

Let’s examine the ways that intermittent fasting can improve gut health, as well as when you should or shouldn’t fast and who may not benefit from IF.

3 Ways Fasting Can Improve Gut Health

When patients ask me how fasting can improve gut health, I have to stop myself from saying, “Everything!” Seriously, though, the evidence is clear — IF benefits your metabolism, microbiome, and inflammation.

One of the mechanisms behind fasting’s incredible benefits is autophagy, the automatic “cleaning” process your cells use to get rid of what they no longer need. This is one reason for many of the effects of intermittent fasting, but have a specific impact on how well the cells of your gut lining get and stay healthy.

LISTEN: Gwyneth Paltrow x Dr. Will Cole: Intuitive Eating, Intermittent Fasting, Inflammation

Benefit #1: Microbiome Diversity

Intermittent fasting is great for human gut microbiome diversity. The microbiome is made of trillions of microorganisms, and microbial diversity is vital for gut health, immune health, and overall health.

A balanced microbiome is important for gut health and overall wellness, and IF positively impacts gut microbe diversity and richness. (1)

Research has repeatedly shown that poor gut bacteria diversity is more common in obese people. (2) Fasting reduces the risk of obesity and may even help with body weight loss.

Benefit #2: Gut Inflammation

I find in my patients that systemic inflammation typically begins in the gastrointestinal system. Fortunately, one of intermittent fasting’s primary benefits is reduced inflammation. (3)

While fasting lowers gut-specific inflammation in inflammatory bowel diseases like Crohn’s and ulcerative colitis, it can also lower inflammatory markers like IL-6 and CRP that contribute to inflammation and immune system dysfunction in other areas of the body. (4)

READ NEXT: Functional Guide To Gut Health

Benefit #3: Gut-Metabolism Connection

Metabolic health problems take root in the gut. Recent studies show that intermittent fasting can improve not only obesity and glucose dysfunction (both metabolic diseases) but also energy metabolism. (5)

Research also shows that fasting can reduce the absorption of bacterial endotoxins linked to insulin resistance and other metabolic problems. (6)

Which Fasting Schedule Is Best?

The most common fasting schedule I recommend to my patients is the 16:8 diet — it isn’t too hard an eating pattern, but it comes with great benefits.

But you should definitely choose the fasting regimen that works for your overall health, family life, work schedule, etc. We should all consider bioindividuality when making health decisions — we all respond positively to different plans.

These are the most common intermittent fasting schedules:

• 16:8 diet — 16-hour prolonged fasting period followed by an 8-hour eating window, usually between 12:00 PM and 8:00 PM.
• 14:10 diet — 14 hours of fasting and 10 hours of food intake, usually between 10:00 AM and 8:00 PM.
• 12:12 diet — also called overnight fasting, 12 hours of fasting and 12 hours of healthy eating, usually between 8:00 AM and 8:00 PM.
• 5:2 method — you eat normally for 5 days out of the week but, on the 2nd and 5th day of the week, restrict your calorie intake to 500-600 calories.
• Alternate-day fasting — you eat normally every other day while fasting or adhering to a severe calorie restriction on the in-between days.
• The Warrior Diet — also called the 20:4 diet, you only eat fruits and vegetables during the partial fasting window until a 4-hour period of time during which you get the remainder of your daily caloric intake. This one isn’t for the faint of heart!

READ NEXT: Causes Of Leaky Gut?

Foods To Eat When Breaking A Fast

When I’m breaking a fast, I prefer to go easy on my gut. Avoiding common dietary irritants like gluten, dairy, and inflammatory carbohydrates while opting for healthful fats and veggies ensures you best support your gut health.

Here are the best foods to eat when you’re breaking your fast:

• Creamless soups or bone broth
• Healthy fats, like eggs or salmon
• Probiotic-rich foods, like kefir or sauerkraut
• High-fiber foods, like broccoli or almonds (take it easy here; too many healthy prebiotics after a long fast might lead to digestive discomfort)
• Blended drinks, like low-sugar smoothies

Who Shouldn’t Fast?

There are some groups of people who shouldn’t try intermittent fasting, such as:

• People with disordered eating
• People with type 1 diabetes
• People trying to build muscle mass quickly
• Children under 18 years old
• People who are pregnant or breastfeeding

Talk to your healthcare provider about starting a new dietary intervention. Everyone is unique, and there may be better options for your specific situation.

READ MORE: Pros & Cons Of Intermittent Fasting

Intermittent fasting has a lot of benefits — a boost to your mental health, blood pressure and heart disease reduction, blood glucose control, circadian rhythm regulation — but most of all, IF helps your gut health. (7)

If you’re ready to dive into time-restricted feeding but need a little help getting started, check out my book, Intuitive Fasting, for the complete guide on how to heal your digestive system by establishing a fasting practice that works for you.

FAQs

Is the impact of fasting on gut microbiota specific to certain conditions or more general?

The impact of intermittent fasting on the beneficial bacteria in your gut helps improve many conditions, including metabolic disorders, heart diseases, chronic diseases, age-related diseases, and more. However, many of its benefits are generalized, such as the potential for more energy, less brain fog, and healthy weight management.

How long should you fast to improve gut health?

To improve gut health, you should fast for at least 12 hours. My patients typically see the best gut improvements when they fast for 14 or 16 hours a day. There are also fasting plans where you fast for 1 day and then eat normally for 1-3 days. Check out what an 18-hour fast really looks like if you’re considering this option. You can also take a look at my Almost-OMAD plan if you’re interested in a more full-day fasting option. 

As one of the first functional telehealth clinics in the world, we provide webcam health consultations for people around the globe.

READ NEXT: Your Gut Health May Be Standing In The Way Of Weight Loss: Here’s What To Do

Sources

• Paukkonen, I., Törrönen, E. N., Lok, J., Schwab, U., & El-Nezami, H. (2024). The impact of intermittent fasting on gut microbiota: a systematic review of human studies. Frontiers in Nutrition, 11, 1342787.
• Liu, B. N., Liu, X. T., Liang, Z. H., & Wang, J. H. (2021). Gut microbiota in obesity. World journal of gastroenterology, 27(25), 3837.
• Popa, A. D., Niță, O., Gherasim, A., Enache, A. I., Caba, L., Mihalache, L., & Arhire, L. I. (2023). A Scoping Review of the Relationship between Intermittent Fasting and the Human Gut Microbiota: Current Knowledge and Future Directions. Nutrients, 15(9), 2095.
• Roco-Videla, Á., Villota-Arcos, C., Pino-Astorga, C., Mendoza-Puga, D., Bittner-Ortega, M., & Corbeaux-Ascui, T. (2023). Intermittent Fasting and Reduction of Inflammatory Response in a Patient with Ulcerative Colitis. Medicina, 59(8), 1453.
• Hu, X., Xia, K., Dai, M., Han, X., Yuan, P., Liu, J., … & Duan, S. (2023). Intermittent fasting modulates the intestinal microbiota and improves obesity and host energy metabolism. npj Biofilms and Microbiomes, 9(1), 19.
• Cani, P. D., Amar, J., Iglesias, M. A., Poggi, M., Knauf, C., Bastelica, D., … & Burcelin, R. (2007). Metabolic endotoxemia initiates obesity and insulin resistance. Diabetes, 56(7), 1761-1772.
• Madkour, M., Giddey, A. D., Soares, N. C., Semreen, M. H., Bustanji, Y., Zeb, F., … & Faris, M. E. (2023). Ramadan diurnal intermittent fasting is associated with significant plasma metabolomics changes in subjects with overweight and obesity: A prospective cohort study. Frontiers in Nutr, 9, 1008730.