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Exercise Affects Your Gut Health?

Gut Health. What even is that? And how do you know if your gut is healthy or not? – it’s not like you can see it, so how can you tell? And why should you care?

Well…Do you get ill quite a lot? Do you feel quite stressed? Do you sleep well?

What Does Our Gut Bacteria Do?

The bacteria in our gut are basically amazing! – just look at the list of their roles in our body(1), which includes:

  • Immunity
  • Contributes to energy metabolism
  • Helps with regulating blood sugar and fats
  • Helps with regulating appetite
  • Makes short chain fatty acids, amino acids and vitamins such as K and B vitamins
  • Makes hormones
  • Metabolises drugs and deactivates toxins
  • Influences gut movement and function

Have you heard of the two-way influence between our gut and our brain (-the gut-brain axis), and because of this our gut is known as our “second brain” (10)!

And gut bacteria may also have a role in brain function and mental disorders(2).

How awesome are all those 100 trillions of bacteria that live in our gut(3)! we need to look after them, so they can look after us!

Factors Influencing Gut Bacteria

  • Diet (5,6)
  • Exercise (4,5,6)
  • Medications, especially antibiotics (5,6)
  • Disease and illness (5,6)
  • Lifestyle (5,6) – like smoking, lack of exercise, stress
  • How we were born – C-section or vaginally, and infant feeding (6)
  • Genetics (6)
  • Age – typically gut flora diversity reduce as we age (7)
  • Geography – where in the world we live (7) – if you live in rural Africa compared to the USA
  • Sleep – if you’re sleep deprivation or if you work night shifts (7)

Impact Of Exercise On The Gut

Exercise stimulates the bowels and can alter how quick food passes through the gut and pops out the other end as poop (4).

The composition of our gut bacteria varies between person to person (11) and also between people that exercise regularly compared to those that don’t  (5).

It’s been shown that exercise can change the composition of the gut bacteria and it appears that the intensity and duration can have an influence too (6).

Exercise can bring on a stress response in our body – the physical and psychological demands of exercise, which in turn can impact on gut bacteria. But our gut bacteria appears to be able to impact on our exercise performance and there’s even research into transplanting bacteria as a performance aid (13) – it’s been done in conditions like Inflammatory Bowel Disease, and the hospital where I used to work has done this with success. So it looks like research is extending into sports nutrition too!

Sports Nutrition & Gut Bacteria

If you’re an athlete or a keen fitness enthusiast, you likely restrict high fibre foods in your diet, as they can bring on gut symptoms during your session. But if you don’t make sure you’re having enough fibre elsewhere in your day, then you could be lacking in an essential nutrient – fibre… And our gut bacteria loooove fibre (6,7)! So a low fibre diet will negatively impact on the diversity of gut flora(3,8).

Depending on your sport or preferred type of exercise, it can influence what your diet looks like (9). For example, if you’re a bodybuilder, you probably tan loads of protein foods and supplements, among other things. And if you’re endurance runner, you’ll likely be avoiding high fibre foods to avoid gut issues (10).

Supplements, high fat diet, high protein diets, low carb diets can all alter bacterial composition and diversity in the gut (8,9).

High protein diets, with low carb and low fibre intake has been shown to negatively influence gut bacteria diversity in endurance athletes (9). And it’s the type of protein as well, that can influence the diversity – animal protein vs. plant protein.

I’ve come across a lot of people that are into their fitness and want to manage their weight, and are following a keto diet. Keto diets have been very popular for several years now. But a keto diet will influence your gut flora, because you’ll be restricting carbs and, if not planned properly, can be very low in fibre. But also, the high fat and high protein in your diet will influence the bacteria (8,9).

I’m not going to focus on individual nutrients, because that would be a massive article by itself! But it’s the type of diet we eat and how varied it is, that will impact on our gut bacteria and our health.

Take-home Points:

  • Gut Health?
    • This includes how effective our gut is at digestion and absorption, if we have any gut issues or diseases, and how healthy we are generally
  • How do you know if your gut is healthy or not?
    • In a basic sense, if you’re not suffering with any illnesses and without any gut problems
  • Why should you care?
    • Gut flora has numerous important roles in our body, and we’ve definitely got more to learn, so given all these roles and the impact on our health, we need to sit up and take note!
  • Gut Bacteria
    • The type of diet you eat influences the diversity of bacteria
    • Your exercise can influence your bacteria and vice versa, so we may be able to improve our performance by manipulating our gut bacteria!

Is exercise good or bad for your gut health? – overall, I’d say it’s good! And exercise has shed loads of other benefits (which I’m not going to list here!).

If you plan your diet well, like considering your health needs, gut needs, sports supplements, exercise and any exercise-induced gut symptoms – you’ll be sorted!

Hope you found this helpful and please let me know your thoughts below.

P.S. You can join my free Facebook Group (IBS & Exercise Nutrition Insiders) here,



It is crucial to get your food and fluid intake right if you want to control your IBS symptoms and if you want train harder, go faster and recover quicker from training sessions and competitions. Dietary requirements are highly individualised and there’s no ‘one size fits all’ approach. Working with an Accredited Sports Dietitian to develop a bespoke plan based on your unique requirements will help to ensure the most appropriate strategy and best results are achieved.

The information, including but not limited to, text, graphics, images and other material contained on this website are for informational purposes only. No material on this site is intended to be a substitute for professional medical advice, examination, diagnosis, or treatment. Always seek the advice of your physician or other qualified health care provider with any questions you may have regarding a medical condition or treatment and before undertaking a new treatment or health care regimen, or before making any changes to your existing treatment, and never disregard professional medical advice or delay in seeking it because of something you have read on this website.

References & Other Reading

  1. Cani, P. D. (2019). Human gut microbiome: Hopes, threats and promises. Gut; 67:1716-1725.
  2. BMJ. (2019)
  3. BMJ. (2018)
  4. Bermon, S., Petriz, B., Kajeniene, A., Prestes, J., Castell, L., & Franco, O. L. (2015). The microbiota: an exercise immunology perspective. Exerc Immunol Rev, 21(21), 70-79.
  5. O’Sullivan, O., Cronin, O., Clarke, S. F., Murphy, E. F., Molloy, M. G., Shanahan, F., & Cotter, P. D. (2015). Exercise and the microbiota. Gut microbes, 6(2), 131-136.
  6. Monda, V., Villano, I., Messina, A., Valenzano, A., Esposito, T., Moscatelli, F., … Messina, G. (2017). Exercise Modifies the Gut Microbiota with Positive Health Effects. Oxidative medicine and cellular longevity, 2017, 3831972. doi:10.1155/2017/3831972
  7. Wen, L., & Duffy, A. (2017). Factors Influencing the Gut Microbiota, Inflammation, and Type 2 Diabetes. The Journal of nutrition, 147(7), 1468S–1475S. doi:10.3945/jn.116.240754
  8. Conlon, M., & Bird, A. (2015). The impact of diet and lifestyle on gut microbiota and human health. Nutrients, 7(1), 17-44.
  9. Jang, L. G., Choi, G., Kim, S. W., Kim, B. Y., Lee, S., & Park, H. (2019). The combination of sport and sport-specific diet is associated with characteristics of gut microbiota: An observational study. Journal of the International Society of Sports Nutrition, 16(1), 21.
  10. Clark, A., & Mach, N. (2016). Exercise-induced stress behavior, gut-microbiota-brain axis and diet: A systematic review for athletes. Journal of the International Society of Sports Nutrition, 13, 43. doi:10.1186/s12970-016-0155-6
  11. Campbell, S. C., & Wisniewski, P. J. (2017). Exercise is a novel promoter of intestinal health and microbial diversity. Exercise and sport sciences reviews, 45(1), 41-47.
  12. Huang, W. C., Wei, C. C., Huang, C. C., Chen, W. L., & Huang, H. Y. (2019). The Beneficial Effects of Lactobacillus plantarum PS128 on High-Intensity, Exercise-Induced Oxidative Stress, Inflammation, and Performance in Triathletes. Nutrients, 11(2), 353. doi:10.3390/nu11020353
  13. Turpin-Nolan, S. M., Joyner, M. J. & Febbraio, M. A. (2019). Can microbes increase exercise performance in athletes? Nat Rev Endocrinol., 15(11):629-630.
  14. Singh, R. K., Chang, H. W., Yan, D., Lee, K. M., Ucmak, D., Wong, K., … Liao, W. (2017). Influence of diet on the gut microbiome and implications for human health. Journal of translational medicine, 15(1), 73. doi:10.1186/s12967-017-1175-y
  15. Chen, J., Guo, Y., Gui, Y., & Xu, D. (2018). Physical exercise, gut, gut microbiota, and atherosclerotic cardiovascular diseases. Lipids in health and disease, 17(1), 17.

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