7 Marathon Nutrition
Tips For Race Week: Improve Your Personal Best

Daniel Murphy // Dietitian // May 24

Running Shoe laced up for a marathon

Table of Contents

Where To Start, Marathon Nutrition

Are you planning on running a marathon this year. At Apex we’ve worked closely with athletes running the Cork marathonDublin marathon and many other marathons across the globe? Marathon week is a crucial time for runners as they gear up for the big race day. Proper nutrition during this period can make a significant difference in performance, energy levels, and recovery. In this articles we’ll explore 7 marathon nutrition tips for race week. These tips will help you get your body in top condition for the race.

Setting the Stage for Marathon Success

Race week is when all the hard work you’ve put into your training starts to culminate. It’s crucial to treat your body right as you approach the big day. Nutrition plays a pivotal role in setting the stage for marathon success. Nerves will always play a part but with an effectively practiced nutrition strategy, food is one last thing to worry about.

Sport nutritionist running a marathon

1. Hydrate, Hydrate, Hydrate

One of the most fundamental aspects of marathon nutrition during race week is hydration. Staying well-hydrated is key to optimal performance and recovery. Dehydration can lead to cramps, fatigue, and poor race-day performance. With dehydration, if you reach around 2% losses, this can significantly impair endurance performance by up to 20%. Going past 2% water losses could possibly mean your race day is over. This is especially important in warmer climates. Runners were met with an extremely warm day in the Cork marathon 2023. It was clear which runners had a hydration strategy and those who didn’t. 


Sweat Testing For A Marathon

You can estimate your hydration needs by doing a sweat test. This is where an Individual weighs themselves before a run in light clothing. They then weigh themselves after an hour of running. Before weighing, the person should wipe the sweat with a towel and wear minimum clothing. The difference in weight will allow you to calculate your sweat losses per hour. 

For Example: If you’re 80kg before the run and are 79kg after a run, this means on average you’re losing 1 litre per hour. 2% Losses from 80kg is 1.6 Litres so you could easily become dehydrated within the 60-90 mins of running depending on temperature. 

Combatting Hot Temperatures While Running

To combat the warm temperatures, an ice slushy can reduce your core body temperature and be the perfect solution to a run on a warm day. Keeping our core body temp down during a race is very important. If our temperature rises too much, it can make it difficult to digest gels and carbs while running the race. As the core temp rises, blood tends to be drawn away from the intestine making it more difficult to digest these carbs. Having a hydration strategy and keeping cool can help prevent this. 

Baseline water requirements start at 35ml per kg of bodyweight. This can vary drastically on training volume and sweat rates. Training and races can see people reach 40-55ml per kg of bodyweight. 

2. How to Carb Load For Race Week

Carbohydrates are the primary source of energy for marathon runners. During race week, you should gradually increase your carbohydrate intake to ensure your glycogen stores are fully topped up. Carb loading is a process of increasing carbs 24-36 hours before the day of the race to provide up 25% increase in energy on the day of the marathon. This can be a difficult process on your own so make sure to get guidance from a sports nutritionist before attempting it. 

During this period, Carbs can increase to 8-12g per kg of bodyweight. For an 80kg person this can mean 800g of carbs over a 36 hour period. If done correctly, carb loading will fuel you for a large portion of the marathon. The main tip is to focus on low fibre carbs such as cereals, juices and syrups. Also lessening high fibre foods such as vegetables and wholegrain products as these can cause stomach cramps when loading. 

3. Carbohydrates and Fuelling

One of the key strategies to prevent hitting the wall is proper pacing and fueling. Start the race at a manageable pace, and consume carbohydrates regularly to ensure a steady supply of energy. Energy gels or chews can be particularly helpful in this regard. Aim for 60-70g of carbohydrate every hour. On average a sports gel will be about 22-25g of Carbs while 500ml of Lucozade Sport is 31g. Take note of gel and sport drink spots on the course and calculate based off your expected finish time how much carbohydrates you’ll need. 

For example: 60g of Carbs x 3 hours = 180g of carbs over the duration of the race. 5 gels x 1 litre of sports drink over the duration. This is in an ideal world but strategy may go differently on the day. 

4. Protein for Recovery

Protein plays a crucial role in muscle repair and recovery. While carbohydrates take the lead in providing energy, proteins help repair and rebuild muscle tissues that inevitably experience some damage during long runs.

Aim to consume about 15-20% of your daily calories from protein sources like lean meat, fish, beans, and dairy products. This can help with muscle recovery and prevent muscle breakdown, especially if you’re doing strenuous training sessions during race week. Many athletes overdo it with protein. 

Protein is a poor energy source. Aim for 1.7g per Kg of bodyweight. This is enough to promote recovery and allows more room for added carbs.

5. Supplements for Marathons

While a well-balanced diet should provide most of the essential nutrients you need, some marathon runners may benefit from vitamin and mineral supplements. Iron, calcium, and vitamin D are often of concern for endurance athletes, as deficiencies can affect performance and overall health.

Gels: An excellent way of fuelling while running. Find a brand that suits you and stick with it. Be sure to check what gels are available on race day so that new foods are not introduced on the big day. Common race day gels are SISEnervit, High 5KineticaMaurten

Beetroot Juice: Taking 1 shot of beetroot juice a day on the 2-3 weeks lead up to the marathon has a vasodilation effect. What does this mean? Beet juice contains concentrations of nitrates which expand blood vessels. In turn, more oxygen is delivered to our muscle allowing us to go for longer. 

Beta Alanine: This supplement works as a lactate buffer. As lactic acid builds up in our muscles, causing pain and soreness. Beta Alanine works by increasing carnosine levels in the body. Reduced lactic acid build up allows us to run for longer distances.

Supplements are a great addition but cannot correct poor fuelling and an incorrect diet. Always look to start with a food first approach and get advice on supplements that will help you hit a marathon personal best on the day. 


"Hitting the wall" is a term often used to describe the point during a marathon when a runner's energy levels suddenly plummet, and fatigue sets in. This phenomenon occurs when glycogen stores become depleted, and the body switches to burning fat for fuel. While hitting the wall can be a real challenge for marathon runners, proper nutrition strategies can help you avoid it.

6. Creating a Race Week Meal Plan

The Last Supper

The night before the marathon is often referred to as “The Last Supper.” This meal is crucial, as it provides your body with the necessary fuel to start the race strong. Aim for a balanced meal that includes complex carbohydrateslean proteins, and healthy fats. Some options could include grilled chicken with quinoa and steamed vegetables or a hearty bowl of pasta with tomato sauce and a side salad.

Avoid heavy, fatty, or overly spicy foods such as fast food that could lead to discomfort during the race. Stick to foods that are familiar and well-tolerated by your digestive system.

Breakfast Of Champions

Race-day breakfast should provide you with a blend of fast-acting and slow-releasing carbohydrates. A good choice could be oats with sliced bananas and a drizzle of honey. Add a source of protein, such as Greek yogurt, to keep you feeling full and satisfied.

Ensure that you eat your pre-race breakfast at least 2-3 hours before the race starts to allow for digestion and prevent any stomach discomfort. It’s also essential to practice your race-day breakfast during your training to ensure it works well for you.

7. Fuelling During the Marathon

Staying hydrated during the marathon is critical to maintain your performance. Dehydration can lead to decreased energy levels and even impair cognitive function. Use a hydration beltvest or use hydration stations along the course to sip on water at regular intervals.

For longer races, consider using sports drinks that provide both fluids and electrolytes to replenish what you lose through sweat. Check out the hydration section of this article to find out exactly how much water you’ll need.

People running a marathon

Success Stories from Apex Nutrition’s Marathon Runners

Marathons are a test of physical endurance, mental resilience, and, of course, the right nutrition strategy. At Apex Nutrition, we’ve been privileged to witness the incredible journeys of our clients who’ve harnessed the power of proper marathon nutrition. We see up to a 20% improvement in running times with our members. Here, we share some inspiring success stories that highlight the significance of tailored nutrition plans and the positive impact they’ve had on marathon performance.

Sub 3 Hour Marathon Success: Sarah

One of the most remarkable success stories comes from Sarah O’Connell, an avid runner and Apex Nutrition client. Prior to seeking our services, Sarah had always struggled with hitting the wall during marathons. Despite dedicated training, she often found herself fatigued and unable to maintain her pace in the latter stages of the race. Sugar cravings were a massive part of Sarah’s week.

After consulting with Apex Nutrition, Sarah received a personalised nutrition plan that included a careful balance of carbohydrates, proteins, and fats. Our expert guidance allowed her to fine-tune her marathon-week nutrition, optimising her hydration strategy, and providing the ideal race-day meal plan.


The results were astounding. In her most recent marathon, Sarah not only avoided hitting the wall but also achieved a personal best time and her goal of a sub 3 hour marathon. With improved energy levels, she maintained a steady pace throughout the race and even had a strong sprint to the finish line. Sarah’s story demonstrates the transformative power of tailored nutrition strategies, and her success serves as a testament to the effectiveness of our approach.

Write Your Story & Reach New Heights

Are you ready to script your own success story in marathon running? Apex Nutrition is here to guide you on your journey to excellence. Our tailored nutrition plans have already transformed the lives of numerous clients, helping them reach new heights in their marathon endeavors. Don’t leave your marathon performance to chance. Take the first step towards realising your potential by reaching out to us today. Click below and schedule a free consultation today. Join the ranks of our successful clients and unleash your full marathon potential with the power of proper nutrition. Your marathon success story begins here.

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Frequently Asked Questions

During the week before a marathon, focus on a balanced diet rich in carbohydrates, lean proteins, and healthy fats. Aim to consume:

  • Carbohydrates: Aim for 8-12g per Kg of Bodyweight. Whole grains, fruits, vegetables, pasta, and rice to ensure glycogen stores are maximised.
  • Proteins: Aim for 1.7g per Kg of Bodyweight. Lean meats, fish, eggs, legumes, and dairy for muscle repair and recovery.
  • Fats: Avocado, nuts, seeds, and olive oil for sustained energy.
  • Hydration: Drink plenty of water and consider electrolyte-rich beverages to stay hydrated.

Carb loading typically begins 24-36 hours before the race. Increase your carbohydrate intake to about 10-12g per Kg of bodyweight. Prioritise simple carbs like orange juice, white breads, white pastas, syrups, honey and more carbs like this. 

Avoid overly fatty and high-fibre foods to reduce gastrointestinal discomfort.

The night before a marathon, have a dinner that is high in carbohydrates and moderate in protein and low in fats. Examples include:

  • Pasta with marinara sauce and a side of grilled chicken
  • Rice with steamed vegetables and a lean meat like fish or chicken
  • Sweet potatoes with a small portion of lean protein Avoid trying new foods and stick to what your body is used to.

On marathon morning, eat a carb-rich breakfast about 2-3 hours before the race. Good options include:

  • Oats with a banana and a drizzle of honey
  • Toast with peanut butter and a piece of fruit
  • A bagel with a small amount of cream cheese or jam and honey.
  • A sports drink or smoothie if you prefer liquids

During the marathon, aim to consume 60-90 grams of carbohydrates per hour. Options include:

  • Energy gels or chews
  • Sports drinks
  • Bananas
  • Energy bars
  • Small pieces of fruit

Drink water or sport drinks at regular intervals.

  • Before: Drink plenty of water in the days leading up to the race. On race morning, aim for 500-600 ml of fluids 2-3 hours before the start of the marathon. 
  • During: Sip water at every hydration station. Aim for 200-300ml every 20 mins. If it’s hot, increase your intake.
  • After: Make sure to rehydrate after with a sports drink, or an iced water slushy to cool down. 

Electrolytes can be found in many isotonic sport drinks so taking additional electrolytes may not be necessary. If taking them on the day make sure to have practiced this previously on your long run and don’t exceed the recommended dose. Too much sodium could actually promote dehydration rather than help your race. 

Avoid foods that are high in fat, fibre, and those that are unfamiliar to you to prevent gastrointestinal distress. Specifically:

  • Spicy foods
  • Heavy, creamy sauces
  • High-fibre vegetables (like broccoli, beans, and cabbage)
  • Wholegrain foods like brown rice/pasta.
  • Alcohol and caffeine in excess

Post-race recovery should focus on replenishing glycogen stores, repairing muscles, and rehydration. Consume:

  • Carbohydrates: Fruits, smoothies, granola bars
  • Proteins: Protein shakes, grilled chicken, turkey, tofu
  • Fats: Nuts, seeds, avocados
  • Fluids: Water, sports drink, chocolate milk.

To avoid gastrointestinal issues:

  • Stick to familiar foods before and during the race.
  • Eat small, frequent meals rather than large ones.
  • Stay hydrated but avoid overdrinking.
  • Limit high-fiber and high-fat foods in the days leading up to the race.

If you regularly use supplements, you can continue to use them as part of your routine. Common supplements include:

  • Electrolyte tablets: These may not necessary as electrolytes are already available in sports. If using these practice beforehand and don’t exceed the recommended dose.
  • Energy gels and chews: For quick carbohydrate intake. Practice and find one that suits during your training.
  • Caffeine: For a performance boost, but test it in training first to ensure it doesn’t upset your stomach.

Avoid trying new supplements on race day to prevent unexpected reactions.

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