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How to fuel on an ultra marathon

A guest blog by Nathan Montague, International Ultra Distance Runner and Coach.

I am certainly not a fan of slogan T shirts. Much more a plain coloured T-shirt and jeans man myself. But I do have a chuckle when I see one particular slogan embossed one large sport conglomerates running attire: “I run so that I can eat cake...”

How to fuel on an ultra marathon

Running at all levels and particularly distance running is almost synonymous with eating. Whether it is as above, an excuse to indulge and enjoy a treat or two as a result of getting through our toils, or rather through nutritional science to fuel for maximum performance and recovery. Ultra-running has almost given a new license on its own not just the face we are putting in more miles so there opening disposing of more calories and therefore that post-race cake is a must rather than just a treat (mine is the biggest slab of homemade fruit variety), we are now given the license to eat on the run.  

What sport actively encourages you to consume your weight in calories and more so the longer you go? Social media conversations and post-race chit chat is all too often pondering the success races based on the performance of their checkpoint buffets. I have heard runners lambast races purely down to their food supply chain being 1* motel rather than a 5* buffet of delights. One of my favourite UK races is the Trail Running Associations Ridgeway 86 where the checkpoints are given ownership to local running clubs along the route. Aside from tea and coffee what is stocked is open to artistic licence with each checkpoint like eating out in a new restaurant. You literally do not know what your going to get. A good distraction from the pain and agony as you anticipate what you are going to get at the next station trying to ignore your screaming legs.  At the opposite end of the spectrum I have completed a 56 mile race where checkpoints consisted of a crate of water bottle dropped along various points of a canal with a box of jelly babies sitting on the top. Not necessarily ideal for those runners who maybe taking a little longer on the route and left with an empty box and if they are lucky the remnants of a few babies hiding in the grass around the now empty water crate.

What to eat on an ultra

How you fuel on an ultra can either aid or destroy your race. With the long list of variables that you have to contest with in ultra-running which you cannot control this is an area you can. With a little thought, pre-planning and preparation, this can go a long way to helping you get to the finish line. Think about fueling rather than just eating as this takes into account whatever you put into your body including liquids, gels, electrolyte tablets and solid foods.

This blog will not give you a definitive answer to what you should eat on an ultra. But rather a platform of knowledge, experiences and information to experiment and build a structure which works for you. One which you can experiment with, tweak and change and develop over time. It is important to know that fueling for an ultra is a transient process. It develops and changes over time. It can differ for race distances, terrain, environment and also the effort and level of fitness you are. I wouldn’t recommend you go out and buy a pair of shoes just because Killian Jornet floated like a Gazelle round the UTMB in them. Considerations of your weight, gait, biomechanics, time on your feet, size and width, your experience and your race level are all factors that need to be considered and this is the same with nutrition within a race.

The science

In laymen’s terms when you eat this increases blood flow to the gut to help you digest the fuel you have put into your body. This also requires water or liquid to help the process. During continuous exercise blood is shifted to your working muscles to deliver oxygen which helps release the glycogen in your muscles to be release and you can run and keep running. Any breakdown in that chain will inhibit or slow down performance. Either lack of oxygen supply to maintain that effort or even diminishing glycogen stores in the muscle. Either way you will slow down. Here entwined we have the paradox. On an ultra we are asking our body to work aerobically. With Oxygen.  This causes a vascular shunt of blood to our working muscles to allow us to keep going. However, in order for us to keep going we need to fuel ourselves and after multiple hours on your feet this is even more vital. When we hit the proverbial wall around 18-22 miles in the marathon and we forced into a stagger this often down to diminished glycogen stores. However, it is our ability to keep those stores topped up, or at least minimally that allows us to keep going in an Ultra or even the marathon. It is also important to train our body to use fat as an energy source but that will be saved for another article. You are now asking your body to strike a balance between this vascular shunt to your muscles but away from your gut to which you need to help you digest and fuel those muscles. The more effort you put in the more complicated it becomes. It is important to note I avoided the term how fast you run as this is individual to each athlete and personal exertion is the note of fuel burning in addition to weight, gender and body composition and training level.

Your body can adequately absorb approximately 200-300 calories per hour while running, in addition, to being able to use up to 90g of carbohydrates. But this can also upset the stomach even before it has been absorbed.  Just because it has gone into the body and even through the system doesn’t mean it has supplied the adequate energy you need. Absorption has to be taken into account. Given all of the above we have to think to ourselves as we stare at the buffet counter of checkpoint 3 in our 100miler and ask: 


“What am I eating, how much and why?”

Calories are important and the more calories that come from fat will have a higher calorific and therefore energy value. But the body may have to work harder to break it down therefore using up vital blood supply and more which you may need to keep you going at that pace you require. Someone who is running through checkpoints grabbing a couple of things and shooting off may well be only taking minimal food as opposed to someone trekking their way through an ultra but we need also need to take into the account the cardiovascular requirements of those individuals and whether their bodies are moving at relative intensities. A runner smashing through may grab half an energy bar and some juice while someone who is trekking at lower aerobic effort level, may stop and eat a couple of mini sausage rolls, a hand full of crisps and move on. The calories are very different but their body’s ability to utilise or absorb differ relative to the intensity they are working at (note not pace!). If you are competing at a high intensity this is a significant factor. How many calories can my body use and absorb and could this lead to gastric issues and an issue later on in the race.

In endurance events carbohydrates are the immediate fuel source. Our bodies need to breakdown carbohydrates into glucose and which is the converted into and stored in the muscle as glycogen in the working muscle. If the energy you are ingesting is in the simplest form, such as sugar or even glucose the quicker the energy will be absorbed and converted for energy use in the muscles. Energy drinks, gels, jelly babies, shot blocs and more, supply energy more quicker than your energy bars, balls, sandwiches and flapjack you pick up at check point. It may seem the obvious answer is to go for the simple sugars for energy then. But there are far too many variables involved for this to work. Often with these fuel sources give energy dips and then troughs. Try fueling on a 100miler with just energy drink or gels and by half way pace and finishing time will be the last thing on your mind as your body battles with the inevitable queasiness and gastric issues. Each gel or 500ml bottle supplies around 150 to 200 calories and therefore that is huge amount you need to put in over the course of a long ultra. This maybe ok on shorter ultras and marathons but the complex mixture of artificial ingredients in many of these products can turn the strongest of stomachs after repeated use and even the next day make a man feel like he has had a night on the razzle, the mere sight of an energy product causing the stomach to whirl and the inevitable retching. A day on artificially constructed, high sugar, and high energy drinks and gels and has a massive impact on the bodies digestive system and balance. Something to take into consideration.

When I speak of shorter ultras, I must emphasise to time on your feet. While an ultra of 50km or even 100km may sound short to some elite runners who may spend up to 7 hours on their feet and the relative amount of calories they ingest is much less. Subsequently, an exceptional few, such as Elite Brit Steve Way, maybe able to rely on just gels and energy liquids. When spending double the time on your feet a plan such as this could be potential highway to gastric issues and the destruction of your race.  

What else should you eat then?

Experience, sound nutritional advice and studies suggest to me a plan which involves fueling as natural as possible in the early stages and in particular the early stages of races. Some of the best ultra and distance specialists around the world feast on dates and other dried fruit, salted nuts and similar particularly in hot environments and multi day stage races to fuel them through their races. The benefit of nuts and also salted varieties is they help replace some of the sodium lost in the battle. But additionally, they are rich in calories and high in protein which studies have suggested can begin to help repair and replenish the muscles even in the middle of racing. When the body depletes its energy stores it starts to breakdown muscle tissue as a source of energy. Keeping protein levels stocked up in a race with a balanced nutrition plan can help but more importantly also help the recovery process for the next day or post-race. This is particularly key in multi-day stage races where you need to be ready to run the next day despite the exertion you have put your body through. A carbohydrate to protein balance of 4:1 in your nutrition is adequate and there are even a number of good sports drinks on the market that offer that kind of balance. But feeding back to the real food issue, nuts however good can leave a grainy, gritty taste in the mouth, and particularly a dry racers gob! Additionally the need to munch these up and digest these can have numerous implications given dehydration and taking fluid away from the system to help. A simple mashed potato, milk, grated cheese and lightly salted mix can work wonders to help offer a good balance of macronutrients (carbohydrates and protein) but also needed sodium too. The neutral and unsickly taste with no requirement to chew (as easy as a gel from a plastic food bag!) but also given a slow energy release to fuel the subsequent hours ahead. Alternatives include home-made rice cakes, sweet potato brownies, rice balls, energy bars, flapjacks and wraps are used by both elite and novice ultra-runners around the world including World 24hour silver medalist Robbie Britton and author and US record holder Scott Jurek. These real alternatives could help anybody and with a little preparation and creativity in your own kitchen you can fuel the longest ultra. A simple search engine flicker and you can find a whole line of recipes to try on your next run.

Personally on long ultras of above 100km, for ¾ of the race I will use a combination of normal or sweet potato mash to help fuel me through alternating with part of an energy bar every hour. Eating real food and bringing in a balanced amount of protein into my race nutrition has improved my recovery rate and the delayed onset of muscle soreness (DOMS) post-race. This is particularly important in injury prevention but also recovering in multi-days. It is about being as creative as possible with foods that contain the right macronutrient balance, which are palatable and digestible but also something that can be transported, accessed and eaten on the move. Alongside the mash mix and energy bars I take on an electroltye drink and water in between and is topped up with 1-2 electrolyte tablets each hour (such as S-Caps) if the conditions are very hot. In more tempered conditions the electrolytes I get from my energy drinks and food is enough. If you are someone who has an excessive sweat rate or maybe suffers from cramps in the hamstrings or calf muscles there is a possibility you might be losing a lot of electrolytes. For more thorough investigation companies are now offering sweat tests to help give you specific information but you perform a simple test yourself. Under specific race conditions weigh yourself before and after a run of approximately an hour without consuming any fluid or food and this will tell you exactly how much fluid you have lost and what you may need to replace.

It is more beneficial to eat real food early on in the race, when exertion is lower, and there is less demand on the working muscles. This will release energy slower and keep you topped up until later. Ideally it maybe more beneficial to switch to simple sugars later on in the race in the form of gels, sweets or the nutritional brands sweet alternatives such as shot blocs which have the added benefit of electrolytes. This could also be of benefit with you have a significant energy dip at any point in the race too.  This will provide a good energy boost and quickly as they will be broken down much quicker and released to the working muscles. This method is used by many runners and understanding the difference between what your body needs and psychologically what you craving is also important.

What you eat on a race as I have said before depends on many factors. Effort, exertion, environment and length are important. For me eating on the run is purposeful - to get to the finish line. I go for simple and palatable foods and save the treats for the finish line excluding my sugar treat of Percy pigs, my present from M&S in the latter stages of the race. Robbie Britton has his Jelly Meerkats, Damian Hall M&Ms and you will have your own. It is important to understand fueling is a psychological factor as well as I have already mentioned. As you are digging through the miles sometimes the only thing that is willing you to get to the next checkpoint without throwing your shoes in the bush and waving the white flag is the thought of feasting at the next buffet table. There are many reasons and strategies we use to keep going in an ultra and a strategies such as this work at all levels. Even the faster runners who zoom through checkpoints grabbing their specifically prepared nutrition backs and home-made energy balls deviate from their plan either for a psychological boost, a craving, climate, gastric issues or their plan is just not working. I have grabbed handfuls of crisps, cheese, salami and cake in ultras. While it is important to plan, it is just as important to be flexible. I have B and C plans too and this doesn’t have to mean carrying a truck load of food in your race pack but just being flexible and thinking on your feet. If it gets you to the end it is great. If it gets you to the end faster and helps you recover quicker even better.

Another important factor in your fueling strategy is a notable source of discourse in the ultra world. Caffeine.  Caffeine is now found in some energy gels, sweets and some of the drinks we consume throughout our runs. Early in my ultra- racing I would never have imagined myself touching the stuff on the run. I do not drink the stuff normally. Not because I am on part of the health police but I would sooner have a coffee! However, flat coke is a significant aspect of my nutritional plan for ultras. In the final third of a race I will replace energy drinks with flat coke. However, I will still continue to drink water to ensure hydration. The sugar and caffeine in the flat coke give such a great energy boost and can really perk up a tired mind and body on those latter stages. On another level when you are 8-10 hours or more into an ultra it can really help neutralise the stomach which can be unsettled after the food and drinks you’ve been consuming.

There is an important factor which needs to be taken into consideration. When you take on caffeine there is obviously a spike where you peak as your body and mind is lifted. However, this needs to be paid back and inevitably there will be a huge drop out as your body begins to pay for that sudden energy surge.  To avoid this wave a key nutritionist at National team meeting suggests continuing with some small form of caffeine every 30 – 60 mins For me this is between 100-250mls of coke. This ensures the do not get the spike and dip but you must be aware you will inevitably suffer post-race in the energy pay back stakes! A drink of tea or small or coffee at a check point is used by lots of runners.  In a race in china over the last 4 checkpoints I downed cups of hot coffee before dashing into the darkness (they didn’t have tea) and during my record run on the ridgeway in 2014 I was having a really bad stage nearly two thirds of the way through the race. A hot sugary tea at a check point literally changed my race. It was an enlightening moment for me in running. Maybe it was the tea, maybe something else but my race changed from falling down the pan to the best run I had ever done in the space of ten minutes and a cup of tea. On one ultra on an exceptionally hot British day I was suffering with significant gastric issues. I couldn’t keep water, coke or any food in my body. The only thing that got me to the finish line was sheer stubbornness and cups of black sugary tea, much to the check point staffs wonder as the temperature rising in the afternoon sun.

What to eat on an ultra

With this information it is important to think about when you take on caffeine if you decide to use this as part of your nutrition plan. It has always made me wonder why some ultras serve coke on checkpoints one and two of an ultra because of the spike and dip issues. Certainly the advice is to take this on later on in the race particularly the last third or quarter of your race to give you that lift to take you to the finish. 

Race nutrition and plans are transient. They will need to change and adapt over timeyou’re your palate, fitness, knowledge and experience changes so will your plans and nutritional needs will need to adapt. Your reaction to certain foods and drink will change as much as your physical fitness training and again these will need to be tested both in training and under race conditions. It is much easier to eat on the move when relative effort is easier but this is much harder when your body and mind is tired when working under race conditions. B races or those which you use as preparation for your main targets are great opportunities to really test your plans. 

This article is by no means a bible to what to eat on an ultra but offers some snippets of advice and guidance to help you make more informed choices. A plan is a great way important but flexibility is key both in the moment and over time. There are some great sports nutritionists working with ultra distance athletes such as Renee Macgregor who has credited with helping international athletes such as Damian Hall, Robbie Britton and amongst others. Good nutrition is vital in racing not only to compete but also to complete ultras but even more importantly to prepare you for your next target. Many injuries can be linked back to poor nutrition in daily life, training and also within races. Think holistically and be creative. Eat what you enjoy but eat to get you to the finish line. Think about your fitness, effort, environment and conditions and what you are fueling with. In the heat your body responds much more significantly to more refined sugar based products where other foods may cause gastric issues as the blood requirements to cool your skin and to your muscles becomes even more important. In the extreme cold or wet cold certain foods you may need to consume more calories as your body attempts to keep itself warm too. Eating little and often is also important to balance the stomach in these conditions. Chocolate and gloopy products don’t go well with heat and extreme cold food can freeze and become impossible to eat.

Eating before, on the run and after is a unique treat and extra dimension and experiment we have in this fantastic sport. Instead of seeing at as a minefield enjoy the road of discovery and treating yourself at the ultra-buffet works for you. Plan, be flexible and test your fueling strategy. Enjoy your food. Enjoy your fuel. What you eat on an ultra can make help or destroy your race. Eat to achieve your goals.

Nathan Montague

International Ultra Distance Runner and Coach


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