Intermittent Fasting for IBS Symptoms and Gut Health
Fasting to improve gut health
Intermittent fasting benefits are becoming widely known in the weight loss world. But did you know that fasting also has a physiological impact on gut health, and can reduce inflammation and improve microbiome?
Hi friends. I’m Hilary Beckwith, ex-dieter and holistic nutrition expert. Clients come to see me with signs of adrenal stress and inflammatory conditions, and my job is to find the root causes so we can address their symptoms more effectively and fill in the gaps between what their doctor is saying and what their body is saying. Click here to read my Medical Disclaimer.
In this article, you’ll learn:
different types of fasting
physiological effects of fasting
why I recommend fasting for clients with PCOS and IBS symptoms
fasting is not a calorie-counting technique
A common misconception among influencers is that fasting is a great way to get your bod into a calorie deficit. But restricting calories is far from the intention (or physiological impact) of fasting and intermittent fasting.
In fact, calorie restriction has been shown to slow metabolism over time, increase hunger hormones, and decrease satiety hormones [1,2].
Whereas water-fasting and intermittent fasting have been shown to increase growth hormone, improve insulin sensitivity, improve metabolic rate, decrease hunger hormones, and improve your body’s ability to burn fat [3,4,5].
To get a bigger picture of how metabolism works, read this article.
types of fasting
As we’ve discussed, fasting is not merely calorie restriction. What you eat before and after fasting, and the timing and quality of your daily meals, are also important factors when it comes to fasting to improve gut health and insulin resistance.
But let’s talk about different fasting terms first, so you can be on the same page as your health practitioners.
INTERMITTENT FASTING: Also known as Alternate-Day Fasting, refers to a water-only fast for 24-72 hours, with careful attention to refeeding after each fast.
TIME-RESTRICTED FEEDING: Often mistaken for Intermittent Fasting, but the two terms are very different. With Time-Restricted Feeding, one would eat daily, consuming all calories within a set window of time. For example, consuming your calories within an 8-hour period, while fasting the for 16 hours, is commonly known as a “16/8” fast.
EXTENDED FASTING: Water-only fasting that lasts longer than 72 hours.
how fasting works
In a nutshell, when fasting is done well, the intention of fasting is to reduce the amount of insulin being released into your bloodstream by eliminating food intake for a period of time.
With time and consistency, this method can help improve insulin sensitivity (more on this) and improve your body’s ability to use fat stores when glucose is not readily available. Put differently, proper fasting increases metabolism and improves your body’s ability to burn fat.
But there is another physiological benefit of fasting that often gets overlooked - intermittent fasting improves gut health and IBS symptoms.
migrating motor complex
The Migrating Motor Complex (MMC) is the key to repairing IBS symptoms and gut issues associated with PCOS. And it is only active in a fasted state.
That does not mean it cannot occur unless you are doing a 24-hour fast, but it does mean that if you are someone who grazes and snacks throughout the day, your MMC may not be activating much at all.
Here’s why that matters.
The MMC is the body’s mechanism for sweeping out unwanted waste and pathogens from the small intestine. It is a cascade of events that increases motility and digestive enzymes during times of fasting, killing unwanted pathogens and moving them through your digestive tract to the point of elimination.
Something to remember is that digestive function, such as the MMC, cannot occur when you are in fight or flight (sympathetic nervous response). Click here to learn more about how digestion works.
The other side of that coin:
Pathogens like bacteria in the small intestine (SIBO) or candida overgrowth LOVE carbohydrates, and they can cause you to crave these foods, or get excessivley hungry more frequently, so they themselves can get their “food” (carbs).
If the MMC helps to sweep out unwanted pathogens, and certain types of pathogens thrive on the nutrients we eat, it makes sense that fasting improves gut health by essentially starving the gut pathogens (depriving them of nutrients), and increasing activity of the Migrating Motor Complex.
why I recommend intermittent fasting for clients with IBS symptoms and PCOS
In conjunction with addressing digestion and adrenal health, eliminating gut pathogens like candida overgrowth, bacterial overgrowth, and parasites reduces systemic inflammation and can make your IBS symptoms disappear altogether, improve pain levels, and reduce PCOS symptoms.
So cool!
It’s important to remember that eradicating gut pathogens requires a more complex strategy than just implementing intermittent fasting into your routine. But it certainly helps (if your body tolerates it well).
If you want to explore fasting for gut health and IBS symptoms, click here to book a free consultation so we can talk about it.
was this helpful?
Has fasting improved your digestive symptoms and gut health?
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BLOG REFERENCES
Zauner, C., Schneeweiss, B., Kranz, A., Madl, C., Ratheiser, K., Kramer, L., Roth, E., Schneider, B., & Lenz, K. (2000). Resting energy expenditure in short-term starvation is increased as a result of an increase in serum norepinephrine. The American journal of clinical nutrition, 71(6), 1511–1515. https://doi.org/10.1093/ajcn/71.6.1511
Most, J., & Redman, L. M. (2020). Impact of calorie restriction on energy metabolism in humans. Experimental gerontology, 133, 110875. https://doi.org/10.1016/j.exger.2020.110875
Kolb, Hubert, et al. “Insulin Translates Unfavourable Lifestyle into Obesity - BMC Medicine.” BioMed Central, BioMed Central, 13 Dec. 2018, bmcmedicine.biomedcentral.com/articles/10.1186/s12916-018-1225-1.
Kahn, B. B., & Flier, J. S. (2000). Obesity and insulin resistance. The Journal of clinical investigation, 106(4), 473–481. https://doi.org/10.1172/JCI10842
Fung, J. (2016). The Obesity Code: Unlocking the Secrets of Weight Loss. Greystone Books.
Bowen, Richard. “The Migrating Motor Complex.” Vivo Pathophysiology, Colorado State University, vivo.colostate.edu/hbooks/pathphys/digestion/stomach/mmcomplex.html. Accessed 30 May 2025.
