Quick heads-up: this is a general guide, not a substitute for medical advice. Everyone’s nutrition needs are different. If you’ve got a medical condition or specific concerns, it’s best to check in with a doctor or sports dietitian. What follows is grounded in current best practices (and science-backed examples from Maurten) to help you train your gut, fuel smarter, and perform your best on race day.
You train your legs, lungs, and mind for race day, but your stomach needs training too. Gut training is all about teaching your body to handle fuel on the run so you can avoid GI issues and keep your energy steady when it matters most.
Why Gut Training Matters
We’ve all seen it happen — maybe even lived it: you’ve nailed the training, you’re running your goal pace, and then… your stomach turns on you. Cramping, bloating, or a sudden dash to the bathroom can derail even the most well-prepared runner.
The truth is, your gut needs training too. Just like your legs adapt to mileage and your lungs adapt to intensity, your digestive system can adapt to fuel. And on race day, that’s the difference between coasting through the last miles or hitting the dreaded wall.
The good news? You can train your gut, and it works.
What Is Gut Training?
Gut training is essentially teaching your stomach and intestines how to handle more carbs while you’re running, so you can deliver energy without discomfort. Think of it like strength training for your digestive system.
Ways to practise include:
Gradually building up towards 60–90g of carbs per hour during runs
Practising your fueling strategy during long runs and workouts (not just saving it for race day)
Sticking to the same products you’ll race with
Running soon after a snack or meal to get used to a fuller stomach
Eating more carbs day-to-day so your body becomes better at absorbing them (your gut actually builds more “transporters” for carbs the more often you use them)
The more familiar your stomach is with race conditions, the less likely it is to revolt when it matters.
How Your Body Uses Energy
Here’s the quick science bit. Your body has limited carbohydrate stores, and at race intensity, you burn through them fast. Once they run low, you’ll slow down; pace, RPE, and even focus will suffer.
That’s why carbs are so important during anything over an hour: they’re your top-up fuel. The catch? When you’re running, blood flow goes to your muscles, not your stomach. Your gut isn’t naturally great at processing large amounts of carbs mid-run. That’s where gut training comes in.
How Much Should You Be Fueling?
The amount of carbs you need depends on both how long you’re running and how hard.
For a marathon, here’s a useful framework:
Beginner: <60g/hr
Intermediate: ~60g/hr
Advanced: 75–90g/hr
Elite: 90+ g/hr
What does that look like in practice? Per hour, it could be:
2 gels (~50g)
1 drink mix + 1 gel (~65g)
3 gels (~75g)
1 drink mix (~80g)
1 drink mix + 2 gels (~90g)
We’ve used Maurten gels and mixes here as examples (since they’re popular with elites and easier on the stomach thanks to dual-source carbs), but any product you’ve practised with works. The golden rule: nothing new on race day.
How to Train Your Gut
Just like you wouldn’t go from zero to marathon overnight, gut training takes time. Aim to build up over at least 8 weeks before race day.
Here’s a sample progression for beginners to intermediates:
Weeks 1–2: 30–40g/hr on easy runs over an hour
Weeks 2–3: Same amount, but practise it in long runs and speed sessions
Weeks 3–4: 40–50g/hr on long easy runs (using gels or drink mix)
Weeks 4–5: 40–50g/hr during harder sessions
Weeks 5–6: 50–60g/hr on long easy runs
Weeks 6–7: 50–60g/hr during harder sessions
Weeks 7–8: 60–70g/hr in a race-day style run
If you’re more advanced, increase by 10–15g/hr every 2–3 weeks.
The aim isn’t to feel perfect every time, a little discomfort in training is completely normal. The key is consistency so your gut adapts.
Common Fueling Pitfalls
Even experienced runners fall into these traps:
Not practising in training
Your stomach needs as much rehearsal as your legs. Don’t wait until race day.
Switching products last minute
Stick with what you’ve trained with. That exciting new gel at the expo? Save it for later.
Skipping hydration
Water helps your body absorb carbs. Don’t just fuel, sip.
Overdoing caffeine
It can boost performance, but tolerance is personal. If you’re new to caffeine, start small in training and see how you feel.
FAQs
When should I fuel during a run?
It’s personal, but a good rule of thumb is every 5–6km, or every 30–45 minutes.
Can I use real food instead of gels?
For long runs at an easy pace, maybe. But on race day, most foods are harder to digest. Stick to simple, low-fibre carbs (like gels or sports drinks).
What if I get GI symptoms?
Slow down, ease back on carbs a little, and keep practising. Your gut adapts over time — training discomfort is okay, race-day meltdowns are not.
Final Thoughts
Gut training isn’t glamorous, but it’s one of the biggest levers you can pull for performance. By practising your fueling in training, you’ll show up on race day with a gut that’s as prepared as your legs and lungs.
Whether you’re taking in 40g per hour or pushing towards 90g, the key is to start early, build gradually, and make your race-day fueling feel second nature.