Marathon runners are famously committed. They follow structured training plans, log long miles, complete strength sessions, schedule recovery, and nail pacing workouts. Yet despite all this preparation, race day can still unravel. Not because of the legs. Not because of the lungs. But because of the gut.

Your digestive system is a muscle like any other, and it needs training just as much as your heart, lungs, legs, and mind. Nutrition is often the missing piece of marathon preparation. Without a well-practised nutrition strategy, even the strongest physical training can fall apart over 26.2 miles.

Whether you’re training for your first marathon or chasing a personal best, a structured and personalised nutrition plan is essential. It fuels training, supports your recovery, trains the gut, and ultimately allows you to perform at your best on race day. This guide walks you through how to build a nutrition strategy that works for you.

Many runners spend months building endurance and speed while overlooking training their gut. This can be costly.

Your digestive system plays a pivotal role in energy absorption and nutrient delivery, both of which are essential during long-distance running. Gut training involves gradually teaching your body to tolerate and absorb the foods and fluids you’ll rely on during races.

By repeatedly practising your nutrition strategy during long runs, your body becomes more efficient at processing carbohydrates under physical stress. This reduces the risk of nausea, cramping, bloating, or energy crashes on race day and ultimately helps you perform better!

This process also helps you identify whether gels, chews, sports drinks, or solid foods work best for you. A trained gut delivers energy more effectively to working muscles and your brain, exactly when you need it most.

Clemence Cleave, Nutritionist at Pure Sports Medicine explains; “Race-day fuelling gets a lot of attention, but marathon performance is built over months. Focusing on a balanced daily diet is the foundation that supports training load, resilience and recovery.”

During most training weeks, emphasis should be placed on nutrient-dense, complex carbohydrate sources such as wholegrains, fruits, and vegetables to support gut health and overall wellbeing. These sources will provide the energy required to sustain long runs and hard training sessions by maintaining glycogen stores.

However, as race day approaches and training volume tapers, your focus should shift toward familiar, easily digested, carbohydrate-rich foods with lower fibre content, such as pasta, rice, potatoes, and bread.

Similarly, protein intake is most effective when spread evenly across the day, using a mix of animal or plant-based sources to repair your muscle tissue and support your training load, while healthy fats should come primarily from foods such as olive oil, nuts, seeds, and avocados, as these contribute to hormone function, vitamin absorption, and overall energy balance

Lastly, beyond macronutrients, a well-rounded diet should incorporate essential micronutrients and plant compounds to enhance your health and performance. Iron supports oxygen delivery to working muscles, calcium and vitamin D help maintain your bone health under repetitive impact, while magnesium assists with muscle relaxation and recovery. Shortfalls in these nutrients may not be immediately obvious but can gradually impact your training consistency and increase injury risks.

At its core, sports nutrition is about providing the right balance of macronutrients to meet training demands and support your performance.

What you eat, and when, has a direct impact on your energy levels, comfort, performance, and recovery. Marathon training moves through distinct phases, each with different nutritional priorities.

• Building phase: focus on establishing a strong nutritional foundation with a balanced intake of carbohydrates, protein, healthy fats, and micronutrients. Prioritise whole grains, fruit, vegetables, and quality protein sources.
• Peak training phase: caloric needs increase as mileage and intensity of workouts rise. Prioritise carbohydrates to maintain energy levels and adequate protein to support muscle repair.
• Taper phase: slightly reduce calories as training volume falls (which naturally happens as your appetite will decrease) but maintain carbohydrate intake to keep glycogen stores full. This ensures you arrive at race day rested and fuelled.
• Recovery phase: the day after the race, prioritise easy-to-digest carbohydrates, hydration, and sufficient protein to accelerate repair.

In the three days leading up to the marathon, carbohydrate loading becomes important. Choose familiar, easy-to-digest foods, limit fibre, fat, and focus on consistent hydration. Keep alcohol to zero or as low as possible.

Ultimately, a well-planned nutrition strategy supports training by replenishing fuel stores, promoting recovery, and reducing gastrointestinal distress.

“Depending on the phase of your training, what you ask of your body changes – building resilience, adaptability, performance and recovery. Getting the right nutrition at each phase gives your body the support it needs to deliver,” states Clem.

Linia Patel,  Dietitian and Performance Nutritionist at Pure Sports Medicine adds, “Vegetables and fruit which contain antioxidants, polyphenols enhance recovery but also nourish your gut microbiome, a hidden ally to sports performance. A healthy gut supports nutrient absorption, immune defence, controls inflammation, and even has a role with mood and mental wellbeing. Active individuals with diverse gut microbiomes often recover faster and adapt better to training.”

Eat Your Way to The Finish Line

Aim to eat a carbohydrate-rich meal with some protein around 3–4 hours before long runs to ensure that your body has the energy reserves needed for sustained activity.

Suitable options include:

• Porridge made with milk and topped with fruit and nuts
• A turkey sandwich on wholegrain bread
• Rice with eggs and vegetables

For Early-Morning Runs

When a full meal isn’t practical, maximise your meal the night before the race, or opt for a lighter snack 30–60 minutes before running to provide a quick and effective source of fuel:

• Banana
• Toast with jam
• Fruit yoghurt
• Small energy bar

These provide quick fuel while being easy to digest.

During long runs, maintaining steady energy levels is crucial to avoid hitting the infamous “wall.” Your body can typically store enough glycogen for around 90 minutes of running. Beyond that, additional carbohydrate intake becomes essential.

For runs longer than 90 minutes, aim to consume carbohydrates every 30–45 minutes using options such as:

• Energy gels or chews
• Sports drinks
• Easily digestible real foods (e.g. jelly babies, fig rolls, banana, flapjack)

Always take gels and chews with water to aid digestion and absorption. As with pre-run nutrition, in-run fuelling must be practised repeatedly in training to refine timing, quantities, and product choice to prevent any surprises on race day.

“On race day, the last thing you want is to experiment. Pack your own snacks and stick to what you’ve practised in training, adjusting for the weather if needed,” notes Clem.

Recovery is just as important as preparation. The right post-run nutrition restores glycogen, accelerates muscle repair, and reduces soreness.

“Post-run, your body is ready for both carbs and protein, so aim to include both in your recovery drink or meal. And don’t forget steady rehydration alongside it”, notes Clem. Effective options include a glass of chocolate milk, smoothies with fruit and yoghurt, a banana and some protein powder, a chicken and quinoa salad, or a peanut butter and banana sandwich.

In general, incorporate anti-inflammatory and nutrient dense foods like berries, leafy greens and tart cherry juice, which may help reduce muscle soreness and support your recovery.

How to Recover After Running a Marathon

Proper hydration is a cornerstone of marathon success and achieving your personal best. Dehydration can impair your performance, lead to cramps, and increase the risk of heat-related illnesses, while overhydration can lead to hyponatremia—a potentially dangerous drop in blood sodium levels.

Key hydration principles:

• Hydrate consistently throughout training, not just on long-run days
• Use water for most sessions
• Add electrolytes for runs longer than an hour or when sweat losses are high
• Drink to thirst, with a structured plan for long runs and race day
• Keep alcohol intake low or at zero.

Additionally, understand your sweat rate, which varies from person to person. This can be determined by weighing yourself before and after a training run to see how much fluid you lose to help refine your strategy.

Despite best efforts, runners can encounter common nutritional pitfalls that hinder performance.

Some of the most common pitfalls include:

• Failing to practise race-day nutrition during training
• Testing new foods or supplements on race day could lead to gastrointestinal issues
• Over-relying on gels and processed products without a solid everyday diet
• Neglecting recovery nutrition can slow recovery and increase injury risk
• Ignoring hunger cues or under-fuelling during high-volume weeks

Having a wide range of options makes eating usually more tolerable and easier on the gut. So, try to practice eating a variety of options. In the long run, your body will thank you.

“Running a marathon is about building adaptability. Planning and fine-tuning your nutrition is an essential tool to support that adaptation,” Clem states.

If you’re not sure where to start or need additional guidance, speaking to a dietitian or  registered nutritionist can help you navigate this tricky part of your training.

Supplements in Marathon Training

Supplements can play a supportive role in marathon training, but they should never replace a balanced diet. “I often see runners taking supplements without being clear on what they’re for or whether they actually work for them. More isn’t always better – supplements work best when used strategically,” adds Clem.

Common supplements for runners include protein powders, electrolyte tablets, and caffeine. Caffeine, for instance, is known to enhance endurance and reduce perceived exertion when taken in moderation before and during a run. However, responses vary widely, so trial it carefully during training or consult a healthcare professional or nutritionist before adding new supplements to your regimen, especially if you have underlying health conditions or are taking medications.

Remember, supplements are just that – a supplement to a nutritious diet and should be used wisely.

Fuel the Training You’ve Worked So Hard For

A strong understanding of sports nutrition, tailored to your individual needs and training demands can have a profound impact on your marathon performance and overall training quality. Nutrition is not an optional addition to marathon preparation; it is a vital component that underpins consistency, and successful marathon preparation.

By fuelling with an appropriate balance of macronutrients, planning hydration carefully, training the gut, and avoiding common nutritional mistakes, you can equip your body to perform at its best.  When applied consistently and personalised to your needs, nutrition becomes a decisive performance advantage rather than a limiting factor. Fuel with confidence, trust your strategy, and support your body every step of the way to the finish line.

Personalise Your Nutrition Strategy with Expert Support

An effective nutrition plan begins with understanding your energy requirements in relation to your training load. Estimating daily caloric needs using your basal metabolic rate (BMR) and activity level provides a useful starting point, but individual needs mean a more precise and individualised approach is often more effective. Our expert team can help refine this framework to better support your performance and recovery.

Emphasising whole, minimally processed foods supports nutrient intake, while adjusting portion sizes in response to hunger, body weight trends, and training intensity helps maintain balance. Just as importantly, your nutrition strategy should remain flexible. Training phases, environmental conditions, and personal preferences all influence your nutritional needs over time.

Regularly reviewing your plan and reflecting on training and race feedback, such as energy levels, fatigue, cramping, or digestive comfort, all allow for ongoing refinement. With a proactive and adaptable approach, supported when needed by our knowledgeable sports dietitian and nutritionists, your strategy can transform alongside your training and continue to support your long-term progress.

Speak to our expert team to discover how personalised nutrition planning can improve your marathon training and racing outcomes today.