What does a healthy diet look like for a marathon runner?

Running a marathon is one of the most physically demanding sports as it can take a toll on the body’s physiological and psychological systems (Carveth, 2025). As such, maintaining a healthy and balanced diet before, during and after a marathon is crucial to fuel workouts and recover efficiently.

A healthy diet for marathon training consists of high-calorie foods, including carbohydrates (carbs), fats, protein, vitamins, minerals, and water. The number of calories an athlete intakes is highly dependent on their body weight, composition, goals, and training intensity (Sayer, 2022). 

For a marathon runner, consuming more carbs and protein is most beneficial to optimise performance and recovery. This is because carbohydrates are the body’s main source of energy and fuel, stored as glucose in our liver and muscles (Olik and The Runner’s World Editors, 2025). During exercise, the body breaks down glucose to provide energy. 

It is also important to consume protein after post-training or race to repair damaged muscle cells and tissue, which helps the body recover faster. Healthy dietary fats also act as a secondary fuel, which helps athletes keep their momentum towards the end of a long run (Utah State University, 2023).

A recommended diet for runners on a regular basis (Eidel, 2022)

Carbs (50-60%): rice, bread, sweet potatoes, beans, cereals

Protein (15-20%): lean meat, low-fat dairy, chicken, eggs

Healthy fats (15-20%): fish oils, avocados, salmon, nuts

Veggies and fruits (25%): bananas, spinach, berries

Pre-run fuel (30 mins to 1hr before)

Before the race, runners usually consume simple carbs, which can be quickly digested and absorbed into the bloodstream (Sayer, 2022). Examples include bananas, PB&J, oatmeal, granola bars, and more. These carbs can immediately provide the body with energy and fuel, giving runners a quick boost before their race. It is not recommended to consume fibre or dairy before a run to prevent gastrointestinal discomfort.

Race fuel (during)

During the race, maintaining carb intake is essential to maintaining a steady pace and delaying fatigue. It is recommended to consume 30-60 grams of carbs per hour to support blood glucose and preserve muscle glycogen levels (Sayer, 2022). The most efficient and practical options to consume during the race are simple, fast-absorbing carbs, such as sports drinks, energy gels, bananas, and gummies, since they can provide an immediate supply of glucose to working muscles.

Post-run fuel (30 mins to 1hr after)

After completing a demanding battle, it is pretty common for athletes to experience a temporary loss of appetite. However, consuming a light meal or snack of carbs and protein is needed to replenish glycogen stores and support recovery (Eidel, 2022). Post-run food options can include protein shakes, fruit smoothies, cottage cheese, and Greek yoghurt to support recovery.

Carbo-loading

The majority of marathon runners also engage in a process called carbo-loading in the final days leading up to their big race. This is a strategy to maximise muscle glycogen stores so athletes won’t “hit a wall” during their race. During this phase, marathon runners significantly increase their carb intake, typically aiming to consume 85-95% of their diet as carbs (Olik and The Runner’s World Editors, 2025). 

Conclusion

Lastly, it is important to note that everyone has different cuisine preferences, training status, metabolic rate, and body composition. As such, everyone’s diet is slightly different, and there is no “perfect” diet for every marathon runner. Instead, nutritional intake should be individualised, so find out what works best for you. Remember, race day nutrition and fuelling should be consistently practised during training.

Reference List

Carveth, J. (2025). 13 Things That Happen To Your Body When You Run A Marathon. [online] Marathon Handbook. Available at: https://marathonhandbook.com/13-things-that-happen-to-your-body-when-you-run-a-marathon/ [Accessed 7 Jan. 2026].

Eidel, S. (2022). Runner’s Diet. [online] Johns Hopkins. Available at: https://www.hopkinsmedicine.org/health/wellness-and-prevention/runners-diet  [Accessed 8 Jan. 2026].

Olik, E. and The Runner’s World Editors (2025). When to start carb loading on marathon week. [online] Runner’s World. Available at: https://www.runnersworld.com/uk/nutrition/diet/a27178213/when-to-start-carb-loading-marathon/ [Accessed 8 Jan. 2026].

Sayer, A. (2022). Marathon Training Diet: What To Eat While Training For A Marathon. [online] Marathon Handbook. Available at: https://marathonhandbook.com/marathon-training-diet/ [Accessed 7 Jan. 2026].

Utah State University (2023). Integrating Dietary Fat: a Guide for Endurance Runners. [online] Utah State University. Available at: https://extension.usu.edu/nutrition/research/integrating-dietary-fat-a-guide-for-endurance-runners [Accessed 8 Jan. 2026].