nutrition for marathon training diet

Marathon Training Diet: What to Eat and When for Optimal Performance

By Danny Webber
Danny Webber is a SENr registered practitioner, an ISAK certified Anthropometrist and a UK Anti-Doping accredited adviser.
| Updated on May 31, 2023

Are you training for a marathon and looking for ways to optimise your diet? Your diet plays a critical role in performance and endurance during long-distance running. This article will guide you to enhance your optimal performance leading to athlete status.

Training for a marathon requires a lot of commitment and determination. It is one of the most challenging events you can put your body through, so getting your nutrition right in your marathon training diet is a massive bonus to support your training and keep you fit and healthy. As you edge closer to the competition, practising your race-day nutrition is important to maximise your performance when it matters most. Get the most out of your training plan and arrive at the start line with these healthy marathon training diet strategies.

Marathon Diet: The Science of Fueling Your Run

What you eat should reflect your energy requirements to fuel your daily training volumes. Consistently under fuelling your body during intense training can negatively impact your performance and lead to illness and injury. Many years of research have consistently shown that muscle glycogen is the primary energy source during endurance exercise, and depletion of these stores is directly linked to fatigue (Bergstrom et al., 1967). Carbohydrates supply the muscles with glycogen, the primary energy source for marathon runners. Carbohydrates are therefore considered to be the best energy foods to fuel as nutrition for marathon training.

For 10k runners, consider reading what to eat before a 10k run.

Diet Before Marathon Training

You should include carbohydrates in your meal plans in the hours before training to fuel your run. The timing of your pre-race meal and what you eat will be down to your preference. However, allow sufficient time (2-4 hours) for the food to be digested to prevent gastrointestinal issues during the race.
Here are a few examples to get marathon runners started:

  • Porridge with dried fruit and honey
  • Bagels with peanut butter
  • Eggs on toast & fruit juice
  • Smoothie

Start thinking about what foods work best for you to plan how to structure your marathon training diet plan.

Nutrition During Marathon Training

As the duration of your training plan increases beyond 90 minutes, you should also practice consuming carbohydrates during training as part of your marathon training diet to maintain energy levels during the all-important long runs. This can be done through carbohydrate-electrolyte drinks, gels, or solid foods. For a marathon, you should consume approx—60 g of carbohydrates per hour (Jeukendrup et al., 2014). Two Energels provide 50g of carbohydrates. Staying hydrated is also essential during prolonged training to replace fluids and electrolytes lost through sweat.

As previously mentioned, monitoring your strategies is important as gastrointestinal issues may occur. Minimising this risk is vital to improving performance.

Nutrition Required After Marathon Training

Recovery is just as important as the training session. If your body doesn’t recover properly, you increase the risk of illness and injury, and training performances may be hindered. High-quality proteins help to repair damaged tissue and promote training adaptations, and 25-30g leucine-rich foods with each meal and after training are an important part of your marathon training diet to maximise this response. It’s also important to replenish your muscle glycogen stores and rehydrate after training.

Milk is the best thing to have after intense training as it is more effective for stimulating protein synthesis and rehydration, improving subsequent exercise performance, and attenuating exercise-induced muscle damage than any commercially available sports supplement (Karp et al., 2006; Shirreffs et al., 2007; Cockburn et al., 2010). Milk is also rich in calcium to promote bone health. You can also make a smoothie with antioxidant-rich fruits if you require additional carbohydrates in your training diet.

Check out my previous article on what to eat after a workout.

Diet for Low-Intensity Marathon Training and Rest Days

If you’re doing a short 30-minute run, does that mean you need a huge bowl of porridge before it? No, it doesn’t. So what do you eat on easy training days and rest days?

Remember that carbohydrates are energy foods, so you don’t need as much nowadays. Reduce carbohydrate intake, increase protein, and include high-quality unsaturated fats (e.g. omega-3).
Easy/low-intensity runs can be done before breakfast to increase training adaptations (Van Proeyen et al., 2011).

This helps the muscles to become more efficient at using fat and carbohydrates as an energy source, reducing the reliance on carbohydrates for fuel, thus preserving glycogen stores for periods of increased intensity, e.g. hill climbs and sprint finishes.

How to Balance Macronutrients in a Marathon Training Diet

A marathon training diet must include adequate amounts of carbohydrates, protein, and healthy fat to balance macronutrients. Carbohydrates are the primary fuel for marathon runners. Highly active individuals and athletes typically have higher needs for carbohydrates and fats than inactive people. Good sources of carbohydrates for marathoners include fruit and veg, rice, pasta, potatoes and cereals.

Protein is crucial after training to aid recovery and helps rebuild and repair damaged muscles, cells and tissues. Good protein sources for marathon training include lean meats, poultry, low-fat dairy, eggs, legumes and soy alternatives. Good sources of dietary fat for marathon runners include nuts and nut butter, seeds, coconut, avocado, fatty fish and fish oils, and healthy oils like olive oil. It is also important to choose nutrient-dense foods and eat three meals and multiple snacks daily to meet high caloric needs.

Marathon Week Meal Plan

In the days before the competition, it’s important to ensure your primary energy stores (muscle glycogen) are full and you’re well hydrated, so you arrive at the start line ready to race.

Carbohydrate loading diet involves increasing the number of carbohydrates you eat the day(s) before a competition. Consuming 8-10g of carbohydrates per kg of body mass is generally recommended. Therefore if you weigh 70kg, you should aim for 560-700g of carbohydrates. This is the equivalent of 9 large potatoes, 750g raw pasta, or 17½ 500ml bottles of Lucozade sport. In other words, a lot of carbohydrates!

Reducing total fibre intake and avoiding large quantities of dairy, fat and protein-rich foods are recommended to prevent gastrointestinal discomfort.
Instead, focus on energy-dense carbohydrate foods with adequate protein and unsaturated fats sources, and hydrate well to support muscle glycogen synthesis.

Check out our Performance Nutrition services for extensive nutrition coaching and support.

Best Foods for Marathon Training Diet

Food IntakeCarbohydrate (g)
100g porridge oats70
300ml skimmed milk15
Tbsp. honey17
2 tbsp. raisins25
2 slices wholemeal toast with jam60
400ml apple juice40
Mid-morning Snack
1 Energy gel25
1 banana25
100g chicken breast0
100g white basmati rice, raw weight85
250g passata15
250g low-fat rice pudding40
1 banana25
500ml Hydration formula11
Afternoon Snack
80g cornflakes (or similar)73
250ml skimmed milk12
500ml Lucozade sport32
100g grilled cod/haddock fillet0
400g mashed white potato, raw weight80
2 grilled tomatoes10
400ml apple juice40

Pre-Marathon Meal Plan

The main preparation is done the days before race day, so the aim of the nutrition before a marathon is to ‘top up the already loaded muscle glycogen stores and replenish liver glycogen stores, which can be reduced to maintain blood sugar levels whilst you sleep.

By this point, you should have extensively practised your pre-race meal in training to be comfortable with it and not cause any digestive discomfort. Based on personal preference, a typical pre-race meal will be a combination of the options listed above, depending on when you should contain 1-4g/kg carbohydrate (1g/kg/hour).

For example, a 70kg athlete eating 3 hours before the race (3g/kg/hour) will aim to have approx—210 g carbohydrates.

You need to focus on hydration in the hours leading up to the race. Water and Nutrition X’s Hydra+ are recommended to ensure you start the race well-hydrated.

Also, Learn about carbohydrates intake recommendations for athletes

**Get 20% off all Nutrition X products using code 20NX.


A well-planned marathon training diet with the right balance of carbs, protein, healthy fats, vitamins, and minerals is crucial for optimal performance and endurance. It reduces inflammation, aids muscle recovery, and boosts your overall performance to achieve your marathon goals. Remember, every runner’s needs are different, and it’s essential to consult a nutritionist or sports dietician to create a personalised diet that works best for you.


Bergstrom, J., et al. (1967). Diet, muscle glycogen, and physical performance. Acta Physiologica Scandinavica, 71, 140-150.

Cockburn, E., Stevenson, E., Hayes, P., Robson-Ansley, P., & Howatson, G. (2010). Effect of milk-based carbohydrate-protein supplement timing on the attenuation of exercise-induced muscle damage. Appl. Physiol. Nutr. Metab. 35: 270–277.

Jeukendrup, A. (2014). A step towards personalized sports nutrition: carbohydrate intake during exercise. Sports Med, 44, S25–S33.

Karp, J., Johnston, J., Tecklenburg, S., Mickleborough, T., Fly, A., & Stager, J. (2006). Chocolate milk as a post-exercise recovery aid. Int J Sport Nutr Exerc Metab. 16: 78-91.

Van Proeyen, K., Szlufcik, K., Nielens, H., Ramaekers, M., & Hespel, P. (2011). Beneficial metabolic adaptations due to endurance exercise training in the fasted state. J Appl Physiol 110: 236–245.

Shirreffs, S., Watson, P., & Maughan, R. (2007). Milk is an effective post-exercise rehydration drink. Br J Nutr. 98: 173-180.


What are the best fruits for a marathon training diet?

All fruits effectively support marathon training, so having a wide variety of 3-5 portions a day is the best approach.

What supplements should I take for marathon training?

Supplements are not a necessity for marathon training, and any recommended supplements will be advised based on the individual athlete’s diet and fueling needs. Contact me to discuss your needs. The main considerations might be: 1) Carbohydrate gels, 2) Electrolyte tablets, 3) Whey protein, 4) Vitamin D3 during the winter, 5) Omega 3.

Why am I gaining weight while training for a marathon?

You are overeating for the training you are doing. A common reason for this is that you are underfilling before and during training and therefore overeating when you get home because you’re starving. Get in touch as I can help you with this.

What are the best drinks for hydration during marathon training?

Water is always the best choice throughout the day, but including an electrolyte tablet can help you replace salts lost through sweat during and after training. Cow’s milk is the best option after your long runs to promote recovery.

What is the best last meal before a marathon?

A marathon typically starts in the morning, so a combination of (well-practised) breakfast options such as porridge with banana and honey, bread with jam/honey/peanut butter and fruit juices are all good pre-race breakfast options.

When should you eat after training for a marathon?

Recovery should start soon after you finish training, especially for long weekend runs. A pint of milk or a smoothie is a great option, especially for runners who do not have an appetite after training, but a well-balanced recovery meal should follow this.

When should I start carb-loading for a marathon?

1-2 days before a marathon is ample time to carb load to maximise muscle glycogen stores.

Can you lose weight while training for a marathon?

Yes, very easily, so long as you have a well-planned nutrition strategy to maintain sufficient energy levels to train and you don’t sacrifice performance for weight loss.

How to avoid marathon training weight gain?

A common reason for gaining weight during marathon training is because you are underfilling before and during training and overeating when you get home because you’re starving. Get in touch if you need help with this.

What do marathon runners eat for breakfast during training?

Marathon runners should eat what they plan to eat on race day before training, so it is tried and tested, known to work well when performance matters most, and won’t cause any upsets!!

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