46. Your Gut, Your Brain & Your Performance: The Science Behind the Connection (Part 2)

In this episode, the Emily and AJ dig into the gut-brain connection, busting the myth that gut-produced serotonin directly controls your mood, and explaining how exercise redirects blood flow away from the GI tract, causing the nausea, cramping, and bathroom emergencies endurance athletes know all too well. They close out with practical guidance on tuning nutrition, hydration, and training around your body's individual GI responses rather than chasing a one-size-fits-all "perfect plan."

5 Key Takeaways:

1. Your gut produces ~90% of your body's serotonin, but that serotonin can't cross the blood-brain barrier — so gut health doesn't directly "fix" your mood or depression the way people assume.
2. Feeling better after improving gut health is likely an associative effect (better digestion, sleep, and energy), not a causative boost in brain serotonin.
3. During intense or prolonged exercise, blood flow is diverted from the gut to the muscles, heart, and lungs — a process that can trigger nausea, cramping, bloating, and diarrhea in endurance athletes.
4. GI distress during endurance sports is a "perfect storm" of heat, dehydration, physical bouncing, and hard-to-digest high-glycemic fuel (like gel packets) hitting a gut with minimal blood flow.
5. There's no universal "perfect" nutrition plan — timing, food quality, and individual GI tolerance all matter, and the only way to dial it in is by testing how your own body responds.

"Remember that your body is a very intricate system, and you can't always isolate nutrition from stress. They truly go hand-in-hand, and you also can't isolate digestion from your nervous system. So if you're looking at it that way, you basically can't isolate performance from recovery either." - Emily

Connect with Emily and AJ

Website: https://www.emilylevercoaching.com/

Instagram: https://www.instagram.com/bedellever/

References

https://link.springer.com/article/10.1186/s44410-025-00011-9

https://pubmed.ncbi.nlm.nih.gov/31377851/

Enjoyed the Episode?

If this conversation resonated with you, make sure to subscribe, leave a review, and share this episode with a friend who's stuck in the start-over cycle. Your support helps more people find the podcast and build healthier habits that last.

Until next time—keep showing up, stay consistent, and remember: small steps add up to big change.