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The Power of Fasting: Healing the Gut and Brain Barrier


In the pursuit of optimal health, we often find ourselves seeking a magic solution, a golden bullet that can address multiple health issues simultaneously. However, the reality is that our well-being is more like a treasure trove of golden pellets, each contributing to our overall health. In this blog post, we'll delve into the intriguing connection between fasting and leaky gut syndrome, exploring how this dietary practice can be a valuable tool in enhancing our health.

Circadian Rhythms and Gut Health

Our bodies operate on an intricate schedule dictated by circadian rhythms. These rhythms govern various physiological functions, including our response to light, sleep, movement and nutrient availability. One crucial element in this system is the suprachiasmatic nucleus (SCN), the central pacemaker of the circadian timing system and regulates most circadian rhythms in the body. When we wake the melanopsin (located in the eye) receives light and signals to the SCN, which synchronises our internal clocks and regulate our bodily functions.

One area where circadian rhythms play a significant role is the gut. Intestinal peristalsis, the movement of the digestive tract, follows a daily rhythm, with reduced contractions at night and increased activity in the early morning. This rhythm contributes to daily excretion patterns.

Another critical factor in gut health is the composition of our gut microbiome. Our large intestine hosts approximately 1.2 kilograms of bacterial cells, most concentrated in a region called the cecum. Remarkably, the composition of these microbes varies throughout the day, influenced by factors such as food intake, sleep, and physical activity. These microbial oscillations are synchronised with the central circadian clock in the hypothalamic suprachiasmatic nucleus.

Fasting: Avoid Eating Three Hours Before Bed.

We have previously mentioned that melatonin slows the signalling of insulin at night, which can lead to a blunted response from your pancreas to late night snacking. The body has pre-programmed jobs to do and digesting food at night is not one of them.

Humans exhibit a daily rhythm in the production of:

  • saliva

  • gastric acids

  • digestive enzymes

  • and bile salts

ALL of which decline late at night.

The circadian rhythm exerts a profound influence on the composition of the gut microbiota. Research has shown that the circadian rhythms are regulated by:

  • timing of food intake

  • sleep

  • sunlight

  • physical activity

All of which are, plays a vital role in shaping the gut microbiome.

These oscillations synchronise the interactions between the brain and the gut, with the central circadian clock in the hypothalamic suprachiasmatic nucleus acting as the conductor of this symphony.

As a result, microbiota's composition and functions fluctuate within hours, aligning with the 24-hour rhythmicity hypothesis of gut microbial function. For instance, the timing of food consumption is crucial in dictating daily oscillations in microbiota composition and function. This interplay between circadian rhythms and the gut microbiota highlights the intricate relationship between our internal clocks and our microbial residents, ultimately impacting our overall health and well-being (source: research on circadian rhythms and gut microbiota composition).

Fasting: A Solution for Leaky Gut

Fasting, specifically time-restricted eating, can play a pivotal role in reducing leaky gut syndrome. Leaky gut occurs when the tight junctions between gut epithelial cells (enterocytes) become disrupted, allowing substances like food antigens and lipopolysaccharide (LPS) to enter our bloodstream. LPS, also known as endotoxin, is a key player in systemic and brain inflammation.

One of the remarkable effects of fasting is its ability to reduce gram-negative bacteria in the gut, subsequently leading to decreased levels of LPS. Gram-negative bacteria can contribute to leaky gut, making fasting a valuable tool in mitigating this condition.

Furthermore, fasting promotes nightly mucus secretion and cellular repair processes in the gut, maintaining its integrity and protecting against LPS infiltration. As much as 70% of our immune response is influenced by the gut microbiome, making it a critical element in our overall health.

FASTING can help to increase bacteria in the gut that produce butyrate that prevents these tight junctions from opening.

The Impact of Gluten Sensitivity on Gut Barrier Function

Gluten sensitivity is a prevalent issue, affecting approximately 6% of the population. Although it's distinct from celiac disease, gluten sensitivity can still lead to significant health concerns. One of the key mechanisms behind this sensitivity lies in the protein called zonulin, which is produced by enterocytes in the intestinal lining.

Zonulin has the remarkable ability to modulate tight junctions in the gut, essentially acting as a gatekeeper for the passage of substances. When individuals who are sensitive to gluten consume it, zonulin production increases, causing these tight junctions to open.

This opening can be temporary, lasting for minutes or hours. Consequently, it allows substances to cross the gut barrier that would otherwise be kept out. This breach in the gut barrier is thought to contribute to various health issues associated with gluten sensitivity, highlighting the importance of understanding one's tolerance to gluten and its potential impact on gut health.

Fasting, Cardiovascular Health and Gut Health

Fasting isn’t just beneficial for the gut; it also has a positive impact on cardiovascular health. One aspect of this connection involves LDL (low-density lipoprotein) cholesterol, which plays a crucial role in transporting triglycerides and cholesterol to various cells in the body. Cells cannot make their own triglycerides but can make their own cholesterol.

During fasting, especially in ketosis, the body produces more fatty acids, which, along with ketones, are used for energy. As a result you may find that your LDL levels will increase.

When the LDL particle donates it's cargo of fatty acids to the cells, the LDL particles becomes smaller. When the LDL particle has nothing left it ends up getting recycled in the liver. The ApoB on the LDL surface signals to the LDL-receptor on the liver to be uptake the LDL molecule for recycling in the liver.

What If LDL Does Not Get Recycled By The Liver?

When LPS binds to the LDL molecule, the ApoB protein becomes miss-shaped and cannot get back into the liver for recycling. The LDL gets smaller it turns into vLDL (very low density lipoprotein). Now we have LPS attached to this vLDL particle floating around our circulatory system that ends up getting stuck into the arterial wall. This vLDL particle then recruits an Immune response to the arterial wall and then you get a soft plaque called a foam cell, which matures into a PLAQUE and eventually ATHEROSCLEROSIS.

Infection can cause an INCREASE IN LDL as a protective mechanism against LPS

Fasting and the Brain: Protecting the Blood-Brain Barrier

Just as fasting benefits the gut barrier, it also has a positive impact on the blood-brain barrier (BBB). LPS can disrupt the BBB, making it more permeable and allowing harmful substances to enter the brain, leading to neuroinflammation. This disruption is often an early biomarker of Alzheimer’s disease.

Moreover, when LPS is injected into healthy individuals, it can lead to depression, social withdrawal, and increased inflammation. Fasting can help mitigate this by reducing inflammation and improving tryptophan metabolism, a precursor to key neurotransmitters like serotonin and melatonin.


Fasting, with its profound effects on circadian rhythms and the gut microbiome, emerges as a valuable tool for improving overall health. By reducing gram-negative bacteria and LPS in the gut, fasting aids in preventing leaky gut and systemic inflammation. Additionally, fasting contributes to cardiovascular health by modulating LDL levels and protects the brain by preserving the blood-brain barrier.

However, it’s crucial to remember that there is no single magic solution for health. Instead, it’s the combination of practices like fasting, proper nutrition, exercise, and lifestyle choices that form the golden pellets leading us toward optimal well-being.

In our journey toward better health, understanding the intricate connections between our body’s systems is a powerful step forward.


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