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Ask the expert: Marathon Nutrition

Ben Samuels MSc, Performance Nutritionist at Science in Sport, answers the questions you always wanted to ask about fueling your marathon – from training, to the big race and recovery.


If you want to master the marathon, you have to put in some serious training time. And serious training requires serious fueling. Then there’s the race itself, where the wrong fueling choices could send you straight into the dreaded “wall” – or, even worse, into the porta potty.  


Keen to put this huge piece of the marathon performance puzzle firmly in place, some of the marathoners here at On listed the big questions we have about marathon nutrition. Then, Ben Samuels, Performance Nutritionist at Science in Sport, was kind enough to answer them. 



Pre-marathon nutrition


Ben, what are the main considerations for optimal nutrition during marathon training?  

“Your main goals for nutrition during marathon training are fueling and recovery, supporting athlete health and promoting any desired changes in body composition. 


“With this in mind, nutrition for each day of the training week should vary according to the demands of the day. In short, the higher volume or intensity days would see higher carbohydrate intakes, where lower volume, easy or rest days mean reduced carbohydrate intake. 


“At the same time, protein intake should be maintained throughout the training cycle to support muscle recovery and rebuild and encourage the adaptations you are triggering with your training.”


We heard running in the morning on an empty stomach can be beneficial – what’s your take on that? 

“Fasted sessions, or low carbohydrate sessions as they’re probably better termed, have become a staple in a training week, and for good reason. 


“Designed to be at a steady state or easier, these sessions promote fat oxidation and can facilitate desired changes in body composition as a result. In addition, training in this restricted carbohydrate state can enhance the adaptations in the muscle that support endurance performance.”



What supplements could be considered during the training phase?

“It’s important to say that supplementation is highly individual and where possible food first should be the approach to nutrition.


“That said, supplements can help you meet the performance demands of your training. In particular, it’s worth considering the products that are going to be used as fuelling options on race day, then practicing using those during long runs in training. Also, a combined carbohydrate and protein recovery shake can support full recovery around sessions.”


Ok, so we’re getting close to the main event – What’s your recommendation for the tapering phase and the days immediately before the race? 

“The days leading into a marathon are a key time to promote performance. Foods should be primarily easily digestible carbohydrate, with moderate protein and minimal fats. Carbohydrate intake will likely be in the range of 10-12 grams per kilo of bodyweight per day, for 1-2 days before the marathon. So for a 60 kg runner, that’s 600-720 g of carbohydrate during each day of their carb-load 1–2 days before the race.


“Carbohydrate can be split between main meals (pasta, rice, potatoes, bread), snacks (jelly sweets, energy bars) and fluids (sports drinks). The food choices here are higher GI (glycemic index) to promote muscle glycogen storage. They are also low fiber to reduce the chances of an impromptu bathroom break during the race.


“The early research in sport nutrition indicated that a depletion phase was needed ahead of carbohydrate loading, but more recently it’s become accepted that carb depletion is perhaps not required before you carb load.” 


What should we be drinking ahead of the marathon?

“Fluid volumes vary for individuals in in the lead up to a marathon, but the aim is always to maintain hydration as opposed to over-hydrating. Drink options can include water, juices, electrolytes and carbohydrate-electrolyte type sports drinks – they all meet hydration and energy demands in different ways. 



Is there anything it’s best to avoid in the pre-marathon week?

“Avoid anything new in the week leading in to race-day, try to eat foods that your body is used to. Then in the 1-2 days before the marathon, minimise fats and fiber in the diet to promote storage of carbohydrate in the muscle without feeling overfull or bloated. Oh, and spicy foods in the days before tends to be a no-go as well!”


Race day


How can we ensure we get to the line fully fueled and ready to run strong? 

“Carbohydrate is key in marathon performance, and your nutrition strategy both pre- and in-race should be focused on maximizing carbohydrate intake.


“Pre-race meals should be predominantly carbohydrate. Here, you’re aiming for 1–4 grams of carbohydrate per kilo of body weight – so 60–240 g carbohydrate for a 60 kg runner. And keeping fats and fibers to a minimum in your pre-race breakfast can reduce the risk of gastrointestinal issues during the marathon.


“Food options should be high GI to increase muscle glycogen storage, so white breads, cereals, jams or preserves, white bagels etc. Fruit juices and other sports drinks such as Science in Sport Beta Fuel can be included to increase carbohydrate intake without having to consume excessive amounts of food.”



Ok, so that’s pre-race fueling covered – what about pre-race hydration?

“Fluid intake guidelines in the pre-event window are equivalent to 5–10 ml fluid per kilo body weight, in the 2-4 hours before the marathon. It’s about staying hydrated without drinking to excess. A good indicator you’re well hydrated is if your urine is pale yellow in color. Adding a bit of salt to these drinks is a good way to increase fluid retention."


How much fuel is needed during the race to keep performance high?  

“Fuelling performance in a marathon would see carbohydrate intake targets of 60-90 grams per hour. This can come from a range of options – it depends on your personal preference while you’re racing. Gels and liquids are probably going to be better choices to minimize stomach discomfort, especially when they are truly isotonic, such as the Science in Sport GO Isotonic Energy Gels. 


“Additional electrolytes can also prevent excess dehydration negatively affecting your performance, but the amounts needed there depend on the individual and potentially also the conditions.”


Can caffeine boost marathon performance? What are the considerations for incorporating caffeine into the race day plan?  

“In longer endurance events caffeine in the latter stages can benefit performance. We would advise that you keep caffeine until the back half of a marathon, with doses of at least 2-3 mg/kg (120-180 mg caffeine for a 60 kg runner, taken in one dose) taken 60-90 minutes before your predicted finish time.”




Ok, fast forward to the finish line, we did it! – What’s the best way to fuel the post-marathon recovery process? 

“There are two key nutrients in recovery nutrition: carbohydrate and protein. Carbohydrate is required to replenish muscle and liver glycogen stores that have likely become depleted during the marathon. Protein is required to support the repair and rebuild of muscle tissue. 


“Recovery starts as soon as you cross the finish line, with specific products such as Science in Sport REGO Rapid Recovery combining both of these nutrients to kick-start the recovery process. This should then be followed in the coming hours by a carbohydrate-based meal (pasta, rice, potato etc), with protein (chicken, fish, tofu) and salads or vegetables.”



"What is the impact on the body of a post-race reward beer or two? (Asking for a friend)"

“A post-race beer is a common sight at the finish areas of endurance events but unfortunately this could negatively impacting the recovery process. Alcohol consumption can reduce muscle glycogen synthesis and protein synthesis - two key components of recovery following marathon running. As such, having a beer or two wouldn’t be the first thing I’d suggest after completing a marathon, there are better options at this specific time… A beer can then be enjoyed later in the evening to celebrate your achievements!”


The Expert: Ben Samuels MSc
Ben Samuels MSc is the performance nutritionist at Science in Sport, a leading sports nutrition company that develops, manufactures and markets sports nutrition products for professional athletes and sports enthusiasts. A keen runner over half marathon and marathon distance, when Ben’s not working on his own performance goals, he’s helping elite athletes in cycling, athletics and team sports achieve theirs.


Pro Tips


Coach tip: Andrew Kastor, Head Coach, Mammoth Track Club
“Stay hydrated while training and before a race by carrying a water around from place to place and drinking from it frequently through the day.”
Athlete tip: Joe Stilin, Elite Marathoner, On Zap Endurance
“I eat often throughout the day, never going two–three hours without a small meal. Before a tough session or race my go-to is peanut butter and honey on toast 90 minutes before.”
Athlete tip: Joanna Thompson, Elite Marathoner, On Zap Endurance
“During a marathon, I alternate between taking energy gels with water and water mixed with electrolytes. That way I get fuel to my muscles, while also preventing cramps and dehydration.”
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Relevant References

Burke, L. M., Hawley, J. A., Wong, S. H., & Jeukendrup, A. E. (2011). Carbohydrates for training and competition. Journal of sports sciences, 29(sup1), S17-S27.

Burke, L. M., Hawley, J. A., Jeukendrup, A., Morton, J. P., Stellingwerff, T., & Maughan, R. J. (2018). Toward a common understanding of diet–exercise strategies to manipulate fuel availability for training and competition preparation in endurance sport. International journal of sport nutrition and exercise metabolism, 28(5), 451-463.

Wee, S. L., Williams, C., Tsintzas, K., & Boobis, L. (2005). Ingestion of a high-glycemic index meal increases muscle glycogen storage at rest but augments its utilization during subsequent exercise. Journal of Applied Physiology, 99(2), 707-714.

Thomas, D. T., Erdman, K. A., & Burke, L. M. (2016). Position of the Academy of Nutrition and Dietetics, Dietitians of Canada, and the American College of Sports Medicine: nutrition and athletic performance. Journal of the Academy of Nutrition and Dietetics, 116(3), 501-528.

Talanian, J. L., & Spriet, L. L. (2016). Low and moderate doses of caffeine late in exercise improve performance in trained cyclists. Applied Physiology, Nutrition, and Metabolism, 41(8), 850-855.