Why Your Gut Is Affecting Your Sleep, Mood, and Performance (The Microbiome Explained)

2025-12-10

In the first of a 2 part series, I’m joined by Harvey Fortis, a performance nutritionist and researcher completing his PhD at Liverpool John Moores University, where he studies gut and metabolic responses in endurance athletes. Harvey also works with INEOS Cycling and Total Endurance Nutrition, so he sees first-hand how gut health can make or break performance. We start by laying the foundations of what the gut microbiome actually is, but quickly move into why it matters in everyday life. We explore how gut health influences sleep, stress, immunity, inflammation, mood, and even how well you tolerate training a...

We start by laying the foundations of what the gut microbiome actually is, but quickly move into why it matters in everyday life. We explore how gut health influences sleep, stress, immunity, inflammation, mood, and even how well you tolerate training and racing.

If you’ve ever struggled with poor sleep, anxiety, IBS, repeated illness, or unexplained fatigue, this episode will help you understand why the gut is often the missing piece.

What We Cover

What the microbiome is and why it behaves like a “city within”
Why gut health starts before birth and stabilises early in life
How gut imbalance can disrupt sleep and keep the nervous system switched on
The gut–brain axis and why 80% of signals travel from gut to brain
How chronic low-grade inflammation starts in the gut
Why frequent illness and poor recovery often point to gut health issues
The link between gut health and skin conditions like eczema and psoriasis
Why many performance problems aren’t training issues at all, but gut issues

Key Quote ( 00:09:59 )

“We host around 30 to 40 trillion bacterial cells – roughly as many as your own human cells – and they all work together like a thriving city inside you.” – Harvey Fortis

Key Message

Your gut is more than a digestive system – it’s a living ecosystem that drives energy, recovery, mood, and resilience. When the good bacteria thrive, everything else follows.

How to Connect with Harvey:Instagram – @fortis.sportsci
Website – www.totalendurancenutrition.com

Recommended resources for listeners:

A couple mod highly recommended books

Gut by Giulia Enders
The Athlete’s Gut: The Inside Science of Digestion, Nutrition, and Stomach Distress – Patrick Wilson

2 interesting research documents
The Athlete Gut Microbiome and its Relevance to Health and Performance: A Review
GSSI Sports Science Exchange: Gut Microbiome Function, Stability, and Profiling and Relevance to Athletes

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