Hello Runner,
Welcome back to your weekly moment of endurance nutrition!
Happy Weekend!
How was your week?
This week was busy for me in terms of work, but it was calmer than last week!
I'm following my training schedule to the letter, and I feel really good during my runs this week. You know when everything just clicks?
Last Sunday I had a gentle 10K to do, and despite the heat, it was so good... and at the end I had a P-E-R-F-E-C-T cortado! I highly recommend the place, by the way. If you live in Barcelona or are coming here one day, you have to go to Funky Bakers! Everything they make is good, from the croissants baked fresh every day to the matcha latte. Oh, and they have three locations in Barcelona.
By the way, they make the best chocolate hazelnut babka (not Nutella) I've ever tasted in my life.
This weekend is going to be a little crazy for me, but the kind of crazy I love. Today I'm spending the day at a health conference here in Barcelona, and tonight I'm going to Lisbon, where I'll spend all day Sunday at a nutrition conference in Estoril. I'm super happy and excited.
So, stay tuned for more updates and news coming soon!
Some time ago, I talked about stress and inflammation here in the newsletter, but I didn't make the connection with the gut.
Today, I want to talk about how intense workouts can disrupt your gut and what to do if that happens.
Nowadays, with social media, many running influencers give the impression that training for a half-marathon or marathon is very easy and that anyone can do it and balance it with work, family, routine, etc.
The reality is not quite like that—of course, it will depend on each person's circumstances—but the truth is that the training cycle for long races is not easy and can be unpleasant for many, especially at the end of that cycle (when training becomes more intense).
When your body is under heavy stress — especially during those final intense weeks before long races — your digestive system is one of the first to feel the burden.
Moderate vs. Intense Training
Moderate training is a sweet spot — your body adapts, your energy improves, and your digestion stays mostly calm.
But once training gets intense — longer sessions, double workouts, high kms, fewer rest days — things shift.
Your body moves into what we call a stress response. Cortisol, adrenaline... all those hormones that help you go harder also start pulling resources away from “non-essential” systems — like digestion.
And that's when you think, “After all this effort to get here, I can't stop now, my gut has to hold out.”
And that’s where the trouble begins.
The Gut Under Stress
When stress builds up (physical or emotional), blood flow to your intestines drops.
Less oxygen, less repair, more inflammation.
Add to that:
Dehydration from long runs*
High intake of energy gels, caffeine, and other supplements
Intake of fiber close to training
Shaking of the intestines during impact
…and your gut barrier can literally leak.
This is what we (dietitians/nutritionists) call increased intestinal permeability — or what runners call, well, “GI distress.”
Symptoms? Bloating, cramps, diarrhea, nausea, or that urgent need for a toilet right now.
*Most runners become dehydrated during long runs and do not replace the fluids they lose.
The Critical Phase: One to Two Weeks Before the Race
This period — often the most stressful — it's a combination of everything:
Training load peaks
Nerves and anxiety rise
Sleep often drops
Nutrition sometimes gets sloppy (because you’re tired of everything). But that’s when the gut is most vulnerable.
→ The mucosal barrier thins out, your microbiota shifts, and your digestive tolerance decreases.
You might notice: food that used to sit fine now might feel heavy, or a gel that was your “go-to”? Suddenly makes you nauseous.
If this is unfortunately your current situation, here are some recommendations and tips to follow to protect your gut from excessive stress.
TIPS
How to Protect Your Gut (Nutrition + Habits)
Just like your muscles, you can adapt and recover your gut!
Here’s how:
Hydration first
Even slight dehydration reduces gut blood flow.
→ Sip regularly — water, electrolytes, or diluted juice if you prefer something with flavor.
Avoid sparkling liquids
Train your gut early
During your training weeks, practice fueling. Find out what works best for you and stick with it. Your gut is a muscle — it learns tolerance through repetition.
→ Same gels, same timing, same hydration plan.
FREE DOWNLOAD
Nutrition Planner
A step-by-step nutritional planner built specifically to help you identify dietary triggers, refine your fueling strategy, and optimize your performance without gut distress.
Feed your gut bacteria
Add prebiotic and probiotic foods to your diet if needed. They help restore balance when stress throws it off.
→ Think about kefir, yogurt (sugar-free), sauerkraut, kimchi, kombucha, tempeh, bananas, oats.
If you cannot tolerate fermented foods, probiotics in capsule form may be a good option.
Gif by TrueMose on Giphy
Keep meals simple near race day
Avoid high-fiber or high-fat meals 24–48h before racing.
→ Stick to white rice, pasta, white bread, eggs, bananas — easy on the gut, easy to digest.
Manage stress (for real)
Managing stress here is key, especially because you won't be able to skip the intense training.
→ Short breathing sessions, 15 minutes of stretching or reading before bed, gentle yoga, a quiet walk without your phone, and spending time in a park or garden — all help lower cortisol.
Gif by bombaysoftwares on Giphy
As I mentioned in the newsletter previously, a healthy gut refers to the well-being of your digestive system and is crucial for proper digestion, nutrient absorption, immune function, and even mental health.
Often, we will not have control over intense workouts, but we can protect and relieve our gut from the stress of these training sessions.
The more you do to protect your gut, the better you will perform in competitions and the more chances you will have to improve your performance.
Track of the week 🎧️
This week's Track of the Week is an older EDM track (it's already 10 years old), but with the perfect beat to match your running pace.
I Love It When You Cry (Moxoki) Radio Edit by Steve Aoki, Moxie Raia
Wishing you a great weekend and week ahead!
Here’s to health and good runs⚡️
Ana Paula Alonso