MARATHON NUTRITION PLAN: HOW TO FUEL BEFORE, DURING AND AFTER RACE DAY

Published: 01/04/2026 | By: Priya Gopaldas

Four weeks out from a marathon, every runner knows the feeling: long runs are peaking, legs feel like lead… and suddenly, the fridge becomes your best friend. Dr. Priya Gopaldas has learned the hard way that even the most disciplined training plan can unravel if your fuelling isn’t spot on. Marathon nutrition isn’t just about race day – it’s about the choices you make in the weeks before, how you top up energy mid-run, and how you help your body recover afterwards.

In this guide, our running ambassador shares how to fuel smartly before, during, and after the big day, blending the latest science with what actually works for everyday runners. Get ready to turn your hard work on the roads into a race-day performance you can feel confident about.

Marathon running is essentially a prolonged battle against your body’s energy reserves. Your glycogen stores (stored carbohydrates in muscles and liver) are finite. Once depleted, you risk “hitting the wall”, which is that sudden, heavy fatigue every runner dreads.

A well-planned nutrition plan helps sustain your energy levels, reduces the chances of that heavy fatigue or dizziness creeping in, and supports your muscles as they work (and recover). Most importantly, it improves your overall performance, can help avoid emergency bathroom visits and can help you achieve a PB!

Here are common mistakes that runners make when it comes to nutrition:

• Under-fuelling during training (not eating enough to support your mileage, leading to fatigue and poor recovery)
• Trying new foods on race day (increasing the risk of GI distress or unexpected reactions)
• Ignoring hydration until it’s too late (waiting until you feel thirsty, which is often a sign you’re already dehydrated)

Overcomplicating things (adding too many new products or strategies instead of sticking to what you’ve practised)

In the next part, we’ll discuss nutrition strategies so we can avoid these mistakes! But, let’s start off with breaking down the basic nutritional needs for endurance athletes:

Macronutrients

• Carbohydrates: Primary fuel source
• Protein: For muscle repair
• Fats: Secondary energy (especially in slower efforts)

+ Electrolytes: Sodium, potassium, magnesium – essential for nerve and muscle function (very important to balance if you’re sweating) – check out my previous article for more info on electrolytes

PRE-RACE NUTRITION

During Training

Your energy needs will vary across the week – higher on long run and interval session days where you’re placing more demand on your glycogen stores, and slightly lower on rest or lighter training days. The key is matching your intake to your output (which is highly individualised) so you’re properly fuelled for performance but also recovering well between sessions.

Balancing Macronutrients

Getting the right balance of carbohydrates, protein, and fats is key as each plays a different role in supporting your training and recovery. I’ve never been an advocate of calculating each amount exactly, as it can be time-consuming, and take the fun out of eating. But I focus on the rough proportion of each macronutrient in each meal and focus on adjusting them based on my training day.

As a vegetarian, training 5-6 times a week, my nutrition looks like:

• On a long run day, increasing carbohydrates with meals like porridge with banana to start the day, pasta for lunch, and a tofu curry with rice for dinner.
• On an interval session day (still prioritising carbs but keeping meals lighter and easy to digest) – toast with peanut butter pre-run, falafel wrap post-run
• On an easy run day (maintaining balanced meals with carbs, protein and fats without needing to load up on carbohydrates)
• On strength, HIIT or yoga/pilates days, ensuring adequate protein intake (e.g. Greek yogurt, eggs, lentils, chickpeas) to support muscle repair.
• On top of that, I’m usually working a couple of long A&E shifts each week, constantly on my feet, so I make sure I’ve got easy snacks on hand (fruit, flapjacks, nuts or an energy bar) – just to keep my energy ticking along.
• After a particularly demanding session (or on rest days if I have cravings), I’ll have the occasional chocolate bar, cookie, or cake.

RACE WEEK NUTRITION

Carb-Loading

About 4–5 days before race day, I start to gradually increase the proportion of complex carbohydrates in meals to top up glycogen stores. In practice, that just means adding a bit more of the usual staples – oats, pasta, rice and potatoes – while my training mileage is tapering down.

Simple carbohydrates like fruit or the occasional sugary snack can also have a place during this phase, but it’s easy to overdo it. Too much can leave you feeling sluggish and low on energy – the exact opposite of how you want to feel heading into race day.

A common mistake runners make is dramatically loading up on carbohydrates on the night before your race (rather than slowly increasing your intake in the week before). This helps to minimise GI distress (such as bloating and diarrhoea) and allows for effective glycogen storage without overwhelming the system

As a vegetarian, four days before my race, a typical day of eating would look like:

• Breakfast: Overnight oats with blueberries
• Lunch: Falafel wrap with roasted veg
• Dinner: Tofu curry with rice
• Snack: cereal bar/ cookie

Foods you would avoid in the lead up to race day

I’d recommend reducing the proportion of fibre, fats, fried and spicy foods in your meal (especially on the day before your race). Too much fibre can lead to unwanted loo breaks during your race.

I’d also advise runners to avoid trying anything new (what works for some may not work for you and the day before your big race isn’t a good time to experiment)

RACE MORNING MEAL

Timing Your Breakfast

Most runners benefit from eating breakfast around 2–3 hours before the marathon start, giving your body enough time to digest and absorb the carbohydrates without feeling too full on the start line. That said, the exact timing can vary depending on what you’re eating (larger meals need more time), how sensitive your gut is, and even the race start time. Nerves can also affect digestion, so it’s worth practising your race morning routine during training to find what timing feels best for you.

Race Day Breakfast Ideas

A few ideas of high carbohydrate meals that you could try before your marathon – the key is to keep things familiar, low in fibre and fat and easy to digest.

• Toast with peanut butter and banana
• Porridge/ rice with honey
• Bagel with jam

Caffeine

Research shows that using caffeine before and during endurance events can reduce perceived exertion and improve your overall performance.

BEFORE RACE:

• How much coffee you should drink before a run depends on genetics, how long you’ve been drinking coffee and how much you have daily
• The International Society of Sports Nutrition suggest the optimal caffeine intake to help performance is about 3-6mg per kg of your body weight taken one hour before race start
• For someone who weighs 50kg that would be 150-300mg, which is about 2-3 cups of coffee

DURING RACE:

• To delay fatigue, runners can benefit from topping up their caffeine during the race (around 50-100mg) by consuming caffeinated gels/gum
• Caffeine in gels takes about 45-60 minutes to have a peak effect (gum takes approx. 15 minutes) so ensure to time this well
• For example, I tend to take a gel every 3 miles. I’d take my caffeinated gels (with 100mg of caffeine in each) at mile 6 and 15

Important Considerations:

• If you’re sensitive to caffeine (like me!) then adjust intake appropriately
• Caffeine can cause raised heart rate, digestive issues and affect sleep so use it with caution
• Never try caffeine for the first time on race day

Hydration Checklist

Making sure you’re well hydrated on race morning can make a huge difference to how you feel in those later miles.

• Start the day with 400–600ml of water (with electrolytes) on waking
• Sip fluids steadily in the 2–3 hours before the start (rather than chugging last minute
• Consider an electrolyte drink if it’s warm or you’re a salty sweater
• Check your urine colour (pale straw = well hydrated)

Avoid over drinking right before the race, as this can leave you feeling bloated and searching for a toilet at the start of the race.

HOW TO FUEL DURING THE MARATHON

Energy Sources While Running

Once you’re running, your body is burning through glycogen stores quickly, so topping up carbohydrates becomes essential.

Most runners rely on:

• Gels (quick, convenient, easy to carry; but can be sickly and may cause GI discomfort if not taken with water)
• Chews (easier to pace and often taste better than gels; but can be harder to eat while running and stick to teeth)
• Carbohydrate drinks (combine fuel and hydration in one; but not easy to carry)
• Real food (e.g. bananas or dates) (easier on the stomach for some; but bulkier to carry and less practical mid-race)

Timing and Frequency

A general guideline is to aim for 30–60g of carbohydrates per hour, though this can increase up to 90g/hour for more experienced runners who have trained their gut.

In practice, that often looks like:

• 1 gel every 20–30 minutes
• Starting early (around 20–30 minutes into the race), not waiting until you feel fatigued

Electrolytes and Hydration

Electrolytes (particularly sodium) help maintain fluid balance and prevent cramping. If you’re sweating heavily or it’s a warm day, these become even more important.

You can get these from:

• Electrolyte tablets or drinks
• Some gels that include sodium

Signs You’re Running Low

It’s worth knowing the warning signs:

• Dehydration: dizziness, dry mouth, headache, dark urine
• “Hitting the wall”: sudden fatigue, heavy legs, cramping, irritability

If you feel this coming on, slow the pace slightly and get some quick carbohydrates in to help you recover.

PRACTICAL TIPS FOR ON-THE-GO NUTRITION

Practice Your Fuelling Strategy In Training

This is probably the most important rule: never try anything new on race day.

Your long runs are your opportunity to:

• Test different gels or fuel sources
• Practice timing of nutrition
• See what your GI system tolerates

Carrying Your Fuel

There are plenty of ways to carry nutrition comfortably:

• Running belts
• Shorts or leggings with pockets (my favourite marathon shorts are the Nike trail ones because of the pocket space!)
• Hydration vests

It’s worth experimenting to find what feels the most comfortable, especially over longer distances.

Avoiding GI Distress

Gut issues are one of the most common race-day problems. To minimise the risk:

• Avoid high-fibre, fatty, or unfamiliar foods before running
• Don’t overload on gels all at once – space them out
• Take gels with water where possible to help absorption

POST MARATHON NUTRITION

Immediate Post-Finish Line: First 30 Minutes

This is your prime recovery window. Your muscles are most receptive to replenishing glycogen and repairing damage.

• Aim for a 4:1 ratio of carbohydrates to protein.

Simple options include:

• Chocolate milk
• A banana with a protein shake
• Yogurt with fruit and granola

Even if you don’t feel hungry straight away (which is very normal), try to get something small in.

THE HOURS AFTER THE RACE

Rehydration

You’ll likely be in a fluid deficit, so:

• Sip water regularly
• Include electrolytes to replace what’s lost in sweat

Meals to Support Recovery

Once your appetite returns, focus on balanced meals:

• Carbohydrates to replenish glycogen (rice, pasta, potatoes)
• Protein for muscle repair (eggs, tofu, lentils, yoghurt)
• Healthy fats to support overall recovery

Foods to Avoid

Right after the race, it’s best to avoid:

• Alcohol (can worsen dehydration and delay recovery)
• Very heavy or greasy meals (harder to digest initially)

CONSIDERATION FOR SUPPLEMENTS

Most runners can meet their nutritional needs through food, but some supplements can be useful depending on the individual:

• Electrolyte tablets: helpful for hydration, especially in longer or hotter races
• Caffeine (as discussed): performance benefits when used correctly
• Protein powders: convenient for post-run recovery
• Vitamin B12 or iron: particularly relevant for vegetarian or vegan runners (if deficient)

As always, supplements should complement (not replace) a solid nutrition foundation.

RISKS OF UNDER-FUELLING / BENEFITS OF FUELLING WELL

Under-fuelling isn’t just about feeling a bit tired – it can have real consequences:

• Increased risk of injury (stress fractures, muscle strains)
• Poor recovery between sessions
• Hormonal disruption and fatigue
• Reduced performance on race day

On the flip side, fuelling well allows you to:

• Train consistently and recover properly
• Feel stronger during long runs
• Maintain energy levels throughout the race
• Actually enjoy the experience (which is often overlooked!)

A FINAL NOTE

There’s no one-size-fits-all approach to marathon nutrition. What works for one runner might not suit another, and that’s completely normal.

The key is to practice, refine, and listen to your body in the weeks leading up to race day.

And when the day finally comes – trust your training, trust your fuelling plan, and most importantly, enjoy it.