Intermittent Fasting And The Gut Microbiome

In recent years, intermittent fasting has gained popularity in the health and wellness world. It’s been praised for its ability to help you lose weight, increase energy, improve mental clarity, and even help you live longer. These are some big claims – so, what does the science say?

What exactly is intermittent fasting?

The idea is simply to alternate between periods of eating and fasting, and there are several ways to do this. One popular method is the 16/8 protocol, where you eat all your meals within an 8-hour window (for example, 11am to 7pm) and fast the rest of the day. Another approach is the 5:2 method, where you restrict your caloric intake for 2 days of the week and eat a regular, healthy diet for the other 5 days. Then there’s alternate-day fasting, where you fast (or consume a restricted number of calories) every other day.

Does timing really matter?

Most of the studies we have for the effect of intermittent fasting on the gut microbiome come from mice. These studies show several potential benefits, including increased microbial diversity, reduced inflammation, and increased production of beneficial short chain fatty acids (SCFAs). Intermittent fasting also improved cognitive function and increased levels of tryptophan (a precursor for important hormones and neurotransmitters) in the blood, suggesting the gut-brain axis may be involved in mediating the effects of fasting (1).

What we know in humans

Despite convincing evidence in animal studies, we still have a way to go to know how intermittent fasting affects the human microbiome, and in turn, our overall health. Some of the best insights we currently have come from studies of individuals participating in Ramadan in the Muslim community, where individuals fast from dawn to sunset (2).

Some studies have found that after Ramadan, individuals had increased levels of beneficial gut bacteria such as Akkermansia, Faecalibacterium and Roseburia. Fasting also increased microbial richness (number of different species in the microbiome) and diversity (how diverse and evenly spread out species are), and increased levels of the beneficial SCFA, butyrate which are all generally associated with a healthy gut microbiome.

Before you try it

We do know that what we eat, rather than when, has a major influence on the microbes living in our gut. A diet high in fibre provides fuel for these beneficial microorganisms, and in turn, they provide us with substances that benefit our metabolism, immune system, and even mental health. When considering how a fasting diet might impact your microbiome you might like to consider how it would fit into your lifestyle and impact the types of foods you consume.

Limiting late-night snacks for example can be a positive choice because generally, these aren’t the types of foods known for their health benefits. Skipping breakfast, on the other hand, could naturally cut out gut-healthy foods like whole grain oats, yoghurt, or fruit. No matter what time of the day, incorporating more varieties of whole foods into your diet can help improve the health of your gut microbiome.

It is important to remember that intermittent fasting is not for everyone and can be associated with some risks. It is not recommended for certain people, such as children, pregnant or lactating women or those at risk of an eating disorder.

If you are interested, contact us to see if intermittent fasting is right for you and your gut health.

In Health and Love

Deena