Endurance

How to Fuel for an Ultramarathon: The Ultimate Guide

01 Feb 2026 | Greg Potter

Whether for the thrill of challenge, the chance to explore the great outdoors, or the prospect of temporarily breaking free from feeling cooped up at home, many people have taken to ultra running of late. However, lots of runners, from novices to elite, are unsure about how to fuel for an ultramarathon, and as there hasn’t been much research on ultra running, many runners rely on anecdote and intuition when choosing what to eat and drink during events.

There is a better way.

The purpose of this article is to provide a helpful guide on how to fuel for an ultramarathon, whether you’re a newbie or a pro. It contains everything from the fundamentals of how to fuel for an ultramarathon to innovative supplementation strategies to enhance your performance and support your resilience. This blog gets a bit scientific in places, so if you don’t care about that nerdy stuff and just want the key points, I’ve used bold font to highlight the practical points. If you’re only interested in specific topics, skip to relevant sections. And if you just want a very high-level overview, here’s a summary of the key points:

Fundamentals of how to fuel for an ultramarathon

  • Some runners do well on high-carb diets, some thrive on low-carb diets. Whatever your carbohydrate intake though, optimal protein intake is probably 1.6 – 2.0 g protein per kg bodyweight per day, evenly divided between meals and snacks.
  • To fill your muscle carbohydrate (glycogen) stores before the race, take in 8 – 12 g carbohydrate per kg bodyweight per 24 h for the 24 – 48 h before the start. Distribute your carbohydrate intake relatively evenly across meals and snacks at this time, and favour high glycaemic index (GI) carbs, such as white rice, white potatoes, and dried fruit.
  • On race day, have a meal containing 1 - 4 g carbohydrate per kg bodyweight 1 - 4 h before exercise. Runners on ketogenic diets might prefer less carbohydrate than this, instead focusing on getting 0.4 to 1.7 g fat per kg at this time.
  • During ultramarathons, the number of calories runners burn each day seems to vary hugely, from less than 4,000 to well over 10,000 calories per day. Runners generally burn calories faster during single-stage marathons than during multi-stage ones, for single-stage ultramarathons are run at faster paces.
  • While running, it’s hard to take in as many calories as you’re burning, so you should consume as many calories as you can comfortably digest (likely 150 – 400 calories per h).
  • Digestion is compromised while running, so it’s important to choose items that are familiar and relatively easy to digest on race day.
  • Most people have fewer digestive troubles and more of an appetite early in a day of running, so you might want to slightly increase your calorie intake at this time to capitalise on this.
  • If you’re experiencing digestive distress while running, merely rinsing your mouth (not swallowing) with a carbohydrate solution (e.g., a sports drink) might actually boost your performance.
  • Your goal should be to begin each day in a state of hydration, not over-hydration or under-hydration. To achieve this, drinking to thirst is generally sufficient, as is consuming sodium (salt) based on your cravings. 
  • When available, go for cold drinks, for these can boost performance when you’re prone to overheating.
  • It’s normal to lose a bit of weight over the course of a day of running. If you stay adequately hydrated on race day, expect to have lost at least 2 % of your bodyweight by the end of the day of running.
  • Practice your race-day nutrition (both eating and drinking) for at least a couple of weeks before the event, and you’ll benefit from mimicking race conditions (pacing, terrain, temperature, etc) as closely as possible in these sessions.
  • Certain supplements can help support your performance and resilience. Caffeine is probably the most consistently performance-enhancing supplement for endurance athletes, particularly when short on sleep. Multiple smaller doses of 1 - 2 mg caffeine per kg bodyweight might be best for ultra running.
  • If applicable, ask your race organisers in advance about aid stations, and carefully prepare and space any drop bags you’ll be taking.
  • You don’t have to overhaul your entire nutrition strategy at once. Instead, choose one thing from this article to try, give it a fair go, and let us know how you get on!

Let’s now take a deeper dive.

Different nutrition strategies are best for different ultramarathons 

I’ll start by stating the obvious: As ultramarathons are simply any runs longer than marathon distance, they can come in a near-infinite number of forms. So, every ultramarathon requires a different nutritional strategy. Most ultras are on trails, but lots are on roads or tracks. Some are single-stage events, others have multiple stages. Another variable is degree of support. At one end of the spectrum, runners are fully supported, with event organisers transporting necessities between stages, including food. At the other end, runners are self-sufficient, with competitors carrying all necessities, including food and water. And then there’s the environment. Several ultramarathons take place in exceptionally inclement conditions, from the heat of Marathon des Sables in the Sahara Desert to the cold of the Montane Yukon Arctic Ultra to the altitude of Khardung La Challenge.

Such large variation between ultramarathons means that the determinants of success in ultra running differ between races. However, there are certain performance predictors that are surely important to performance in all ultras. Some factors that underlie performance are arguably less affected by nutrition, such as cognitive skills (e.g., psychological resilience, decision making), running skills (e.g., pacing, running economy, agility across different terrain), aerobic capacity, and musculoskeletal function. Other factors, however, are quite strongly affected by nutrition, including:

  • Ability to use different fuel sources for energy
  • Bodily fuel stores
  • Other fuel sources (i.e., what you eat and drink during the race)
  • Digestive system function
  • Ability to regulate body temperature

Let’s begin by focusing on your ability to use different fuel sources for energy, which is modified by your habitual carb and fat intakes.

Are high-carb or low-carb diets best for ultra runners?

There is a lot of debate about whether high- or low-carb diets are best for ultramarathon performance. The high-carb diet enthusiasts note that there are plenty of instances of phenomenal ultra runners thriving on high-carb diets. Foremost among these athletes is Yiannis Kouros, the greatest over-24-h-ultra runner of all time. And the research clearly shows that consuming carbs during endurance exercise improves performance compared to drinking water alone.

But then there are contemporary ultra runners who are thriving on relatively low-carb diets. Zach Bitter holds the World Records in the 100-mile run and 12-h run and is arguably the most impressive of these athletes.

There are good theoretical reasons to favour a low-carb approach to ultra running. When athletes spend time in a state of low carbohydrate availability – which they can do by consuming a low-carb diet – they increase how quickly they can use fat for energy, and athletes on very low-carb diets can burn fat at rates of up to 1.5 – 1.8 g per min. This rate should be high enough to sustain performance in some ultramarathons, and the longer the event, the more useful this adaptation should be. 

Next, many people find that consuming a low-carb diet helps with weight loss and preventing weight gain. This is important, for body composition – how much of your body is made of fat mass and fat-free mass – substantially affects running economy (the amount of oxygen needed to sustain a given exercise intensity). Another relevant consideration is that fat contains more calories per gram than carbohydrate and protein, meaning that if you're on a low-carb diet then the weight of food you carry can be lighter. This could be especially advantageous in self-sufficient races.

And then there are those of us whose health suffers on high-carb diets. Some athletes find that typical high-carb sports nutrition products leave them gassy and bloated, and let's just say that I’m not sure that the copious amounts of maltodextrin and sugar in these products are healthy in the long term. Lots of people with poor metabolic health (e.g., blood sugar that fluctuates wildly) also find low-carb diets meaningfully improve their metabolic regulation.

The problem is that at a given bodyweight, low-carb diets may worsen economy. And while low-carb diets were once thought to spare carbohydrate metabolism, they actually seem to impair carbohydrate metabolism, thereby negatively affecting the ability to perform at higher intensities (as needed when running uphill, for example).

And then you should remember that the more restrictive your diet is, the more likely you are to consume too much of some nutrients and not enough of others.

So, should you choose a low-carb diet?

Personally, I’m macronutrient impartial – it seems that people can thrive on a range of carb intakes, and some self-experimentation is both fun and necessary if you want to do your best.

My guess is that your genes are relevant here. Consider the following:

  • Latitude strongly affects how well plants grow - plants grow better near the equator.
  • From generation to generation there is variation in people’s genetics, and genes that confer advantages are more likely to be passed on.
  • It’s therefore likely that among our ancestors, genes that helped them thrive on their local diets were likely to continue to the next generation. This means that you may have inherited genes suited to the diets your ancestors consumed.
  • So, it seems reasonable that if your ancestors lived at high latitudes (close to the North or South Pole), you might have genetic adaptations that make you more likely to do well on a low-carb diet, whereas if your ancestors were from near the equator, you might do best on a high-carb diet.

If you’re happy with how you’re progressing, you should probably just crack on with what you’re doing.

But if you think your diet might be contributing to your poor health or lack of improvement in training, maybe it’s time to try something new? 

If you decide to switch up your diet, you should trial the new strategy extensively in training first and give it plenty of time to discover if it works for you. Certain diets - very low-carb, "ketogenic" ones, especially - take time to get used to and refine... although it does seem that on switching to a ketogenic diet it only takes elite endurance athletes 5 to 6 days to maximise how quickly they can burn fat.) When people first switch to a ketogenic diet, for example, they may experience lethargy and flu-like symptoms as they switch from relying on glucose for energy to relying on ketones, energy-rich substrates formed from the breakdown of fatty acids. (Even if you aren't on a ketogenic diet, you may have experience some of these symptoms, for a recent study found that in a multi-stage self-sufficient race, all ultra runners - even those consuming 9 g carbs per kg bodyweight per day -  entered ketosis.) One reason for these symptoms might be that ketogenic diets reduce muscle glycogen stores and levels of a storage hormone named insulin, leading to water and sodium loss. Sodium is an electrolyte, and its balance with other electrolytes is important to the regulation of blood pressure and various bodily processes. Consuming extra salt (and hence sodium) might therefore help avoid ketogenic diet-induced electrolyte imbalance, easing the transition to this diet.

So, if you want to do a self experiment and trial a different type of diet (e.g., a low-carb one if you’re currently on a high-carb one), I suggest you try it for at least 4 weeks in training first. Maybe, for example, you could try the new diet strategy for a training block (mesocycle) early in your preparation for a race. 

While this is a subject for another time, athletes increasingly recognise the benefits of nutritional “periodisation”, which entails aligning changes in diet with training to support specific adaptations to the training sessions. An example of this is "training low" by doing some training sessions in a state of low carbohydrate availability (i.e., low muscle glycogen, plus no carbohydrate consumption during exercise) in order to boost the effect of training on the number of new mitochondria made (mitochondria function a bit like powerhouses in your cells) and your ability to use fat for energy.

One way of doing this is to eat a high-carb diet up until a hard session in the afternoon, which will somewhat deplete glycogen stores in the exercised muscles. Then consume a low-carb diet the rest of the day and wake up the next day and do a fasted training session in the morning. Soon after, revert to a high-carb diet. In this example, you’d be in a state of low carbohydrate availability from after the end of the first session until after the second.

Whatever your diet, high-quality protein is helpful

Protein is not only key to rebuilding your muscles, it’s also important to immune function and other bodily processes. So, regardless of whether you’re on a high- or low-carb diet, it’s important to consume enough high-quality protein.

Scientifically, the quality of protein you eat depends on its digestibility and amino acid composition (amino acids are the building blocks of proteins). Based on the best metrics of protein quality, the protein in animal foods (e.g., meat, fish, and eggs) is generally much better than that of plant foods, and dairy proteins such as whey are particularly high quality. This is why we use whey protein isolate in Rebuild versions of our ultra endurance product, Long Range Fuel. (Note that the Elite versions of Long Range Fuel are Informed Sport-certified, making them ideal if you’re a drug-tested athlete.) For more on how to use Long Range Fuel for ultra running, check out the Long Range Fuel calculator.

“From the very first try I was hooked! Not only are all of the Long Range Fuel products absolutely delicious, they really do support performance, recovery and holistic health, all with a focus on real, whole food and high-quality ingredients. They are suitable for anyone – from those taking their first steps in sport to those planning a record-breaking endurance adventure, and everyone in between.” - Chrissie Wellington, OBE 

Anyway, how much protein should you eat?

Consume 1.6 – 2.0 g protein per kg bodyweight per day, evenly distributed across meals and snacks. This is a good target during both training and races. (If helpful, you can use an app such as MyFitnessPal to track your protein, carb, and fat intakes.) 

If anything, your protein needs might be slightly higher during races than while training, particularly if you’re running at altitude. Exercise that leads to lots of muscle damage, such as running downhill, might increase protein needs, and as you deplete your muscle carbohydrate (glycogen) stores, your body uses more of the amino acids in protein for energy. This is especially true of the amino acid leucine, which is one reason we add leucine to Rebuild versions of Long Range Fuel.

Right, hopefully it’s clear that protein is important. Let’s now turn to other things to eat.

What to eat before the race 

Before your race, your goal should be to ensure you arrive at the start line with a full tank. Your muscles store carbohydrate as glycogen, and these stores are important for endurance. By tapering your training load and consuming lots of carbohydrate shortly before the event, you can load your glycogen stores above their typical levels. To fill your muscle glycogen stores, consume 8 – 12 g carbohydrate per kg bodyweight per 24 h for 24 – 48 h before the start. Distribute your carbohydrate intake relatively evenly across meals and snacks at this time.

You might benefit from choosing high glycaemic index (GI) carbohydrate sources at this time. The GI is a measure of how quickly a food or drink raises your blood sugar. (Note that adding foods and/or drinks rich in protein, fat, and fibre will tend to reduce blood sugar responses to meals and snacks.) While maintaining relatively stable blood sugar levels is generally good for your health, high GI foods tend to be best at rapidly topping up muscle glycogen.

The items below are very easy for most people to digest and have quite high GIs, making them particularly good options to consume while glycogen loading. These items are also excellent options to use to refuel between runs during multistage races.

  • White rice
  • Instant oats
  • Popcorn
  • White potatoes (mashing further increases GI)
  • Carbohydrate powder. If you’re struggling to increase your carbohydrate intake to high enough levels, consider drinking some of your carbs too. Using a carbohydrate powder is one option. In addition to more commonly used maltodextrin/glucose, and fructose powders, I think highly-branched cyclic dextrin, a high-molecular weight carbohydrate, is a good choice. 

The other key factor during this time is to choose familiar foods and drinks that are easy for you to digest. It’s not the time to be eating lots of cruciferous vegetables (e.g., broccoli, cauliflower), pulses (legumes), or chili peppers, for example!

Let’s shift now to what to consume during the race itself.

What to eat during the race

Your race-day dietary choices will of course depend on whether you perform best on a high- or low-carb diet.

To begin, have a meal containing 1 - 4 g carbohydrate per kg bodyweight 1 - 4 h pre-exercise. This is especially important if your muscle glycogen stores aren’t full (as is typical after the first day of a multi-stage ultramarathon). If you’re on a ketogenic diet, you might prefer less carbohydrate than this, instead focusing on getting 0.4 to 1.7 g fat per kg at this time.

Below are some excellent options to consume during the race.

 Items for runners on low-carb diets:

  • Dehydrated meals. These are ideal for meals for self-supported runners, in particular. Check the protein, carbohydrate, and fat contents to ensure they’re appropriate for your needs.
  • Food bars. There are low-carb ones, and you can also make your own.
  • Nut butters. Several characteristics of nut butters make them ideal snacks for ultra running. One is that they have been somewhat “predigested”. This makes them easier to eat (by reducing chewing), easier to digest, and meaningfully increases how many calories your body can actually take up from the nuts: In this study, for example, the number of metabolisable calories per g almond butter was 48 % higher than the number of metabolisable calories per g of whole almonds. In my biased opinion, Long Range Fuel’s added performance- and resilience-boosting ingredients make it the best nut butter-based product and the best low-carb product in general for ultra runners.
  • Creamed coconut. This is basically desiccated coconut ground into a paste, and it’s delicious. One thing to be aware of is that it does change quite a lot at different temperatures though – it gets very soft in the heat and goes hard when cold, so experiment with it in training.
  • Coconut water. Of the drinks that are naturally quite high in fat, this is a great option. You can also buy coconut milk powder and use it to make your own coconut water. Doing so has the advantage of letting you adjust the drink concentration according to your preferences.

Even runners on low-carb diets will probably benefit from some carbs while running, so it might be worth including small amounts of some items from the next list too.

Items for runners on high-carb diets:

  • Freeze-dried meals.
  • Food bars.
  • Dried fruit.
  • High-carbohydrate gels and drinks. When selecting high-carbohydrate items, it might be best to pick some items that contain both glucose and fructose (different types of sugars). The reason for this is that glucose and fructose are absorbed by different transporters in your gut, meaning that when you ingest them both at the same time you can take up more total carbohydrate than if you only ingested either glucose or fructose alone. A 2:1 glucose:fructose ratio is about right. 
  • Nut butters. These are a staple of runners on low-carb diets but can also be helpful for runners on high-carb diets, especially when there’s a need to minimise how much food they carry. As I explained above, high-quality nut butters have several advantages over whole nuts, and Long Range Fuel is the pick of the bunch.

One thing to be aware of is that you'll probably find that your taste preferences shift over the course of the race, and most people get tired of consuming sweet items and prefer increasingly savoury items as races progress. Because many high-carb items are sweet, this is most relevant for runners on high-carb diets.

Example diet plans for self-supported ultra runners

 

High-carb diet

(E.g., about 10 % protein, 60 % carbs, and 30 % fat)

Ketogenic diet

(E.g., about 10 % protein, 30 % carbs, and 60 % fat)

Breakfast

(4 AM)

Freeze-dried cereal

 

Dried fruit

Freeze-dried meal

 

Added extra virgin olive oil

Snacks while running

(6 AM – 10 AM)

High-carb food bars

 

 

Energise & Rebuild Long Range Fuel (e.g., 2 doses of 0.7 g per kg bodyweight, each spread over 1 h)

 

Low-carb food bars

Snack while running

(11 AM – 3 PM)

Energise & Rebuild Long Range Fuel (e.g., 1 dose of 0.7 g per kg bodyweight, spread over 1 h)

 

High-carb energy drink 

Energise & Rebuild Long Range Fuel (e.g., 2 doses of 0.7 g per kg bodyweight, each spread over 1 h)

 

Coconut milk

Snacks while running

(4 PM – 7 PM)

High-carb energy drink 

 

Flapjacks

Coconut milk

 

Macadamia nut butter

Straight after running

Recovery drink

Recovery drink

Evening meal

Freeze-dried meal

Freeze-dried meal

Before bed

Calm & Rebuild Long Range Fuel (100 g is usually ideal)

Calm & Rebuild Long Range Fuel (100 g is usually ideal)

 

Next, the nutritional requirements of different ultras are very variable. While some studies on this subject haven’t really been representative of ultramarathons run in the wild, the research does give us clues about calorie needs. 

Looking at all the research done so far, at the low end of the range of energy expenditure, a 225-km 5-day ultra required about 3,500 calories a day. However, at the high end, a 24-h single-stage trail ultra required over 10,000 calories per day for some runners. Importantly, runners who better match their calorie intakes to their energy needs tend to perform better, so eating enough is key to performing your best.

Based on the research, it seems reasonable to assume that runners generally burn calories faster during single-stage ultramarathons than during multi-stage ones. In addition to race duration, other factors substantially affect how quickly runners burn calories. For example, running at high altitude substantially increases energy expenditure and how quickly your body burns carbohydrate compared to running at sea level. 

As multi-stage ultras have to be run at lower intensities, it is easier to consume enough calories during them. Most ultra runners find it hard to eat enough though, and this mismatch between energy expenditure and calorie intake results from several factors, including loss of appetite (especially for sweet items) and gastrointestinal symptoms arising from the so-called “exercise-induced gastrointestinal syndrome”.

This syndrome is driven by a few key factors. One factor is a redistribution of blood flow away from the digestive system to the skeletal muscles, which can damage the cells that line the gut, compromising the integrity of the intestinal barrier. This can lead to the entry of nasty bacteria into the blood, triggering an immune response that can perpetuate this problem. Not good. Another factor is that exercise increase levels of stress hormones that may impair the motility of the digestive tract and the transport of nutrients across it. Next, running produces large oscillations of the gut. Although not well studied, this may also contribute to digestive problems. Finally, there are other variables that can compromise the function of your digestive system at races, including competing in the heat, running through the night, nerves, and the menstrual cycle, if you're female. All of these changes contribute to a variety of gastrointestinal issues, and in ultra runners these most often include nausea and the urge to regurgitate. 

In the short term, this syndrome can lead to discomfort and energy imbalance that can hamper performance. in the long term, however, it can contribute to so-called relative energy deficiency in sport (what people used to call the female athlete triad), a state of insufficient calorie availability that negatively affects various bodily systems, impairing immune function, hormone regulation, reproductive health, bone density, and more.

So, doing what you can to support your digestive system function and hence consume enough calories is very important!

How to minimise digestive problems while running

Exercise-induced gastrointestinal syndrome is very common in ultra runners, with more than half ultra runners reporting severe digestive symptoms, some of which are very nasty indeed. These symptoms result from several factors, including reduced blood flow to digestive organs, increased activity in the “fight, flight, or freeze” branch of the autonomic (automatic) nervous system, and injury to the cells of the gut lining, increasing the entry of bacteria to the bloodstream.

Below is a list of tips to help you minimise the likelihood of you experiencing digestive problems while running:

  • Try to go to the toilet before exercise.
  • How much you eat matters:
    • Consuming fewer calories more frequently is probably preferable to consuming more calories less often - aim to eat small amounts at regular intervals each h (e.g., every 20-30 mins). While running, your goal should be to try to consume as many calories as you can comfortably digest - likely 150 – 400 calories per h. 
  • What you eat matters:
    • Whether you’re on a low-fat diet or a low-carb one, it’s important to select foods and drinks that are easy to digest. A simple strategy that is often very effective is to consume a relatively low-fibre diet from the day before the race until the end of it. 
    • If you experience digestive discomfort, selecting low-“FODMAP” items might help. (FODMAP stands for fructose, oligosaccharides, disaccharides, monosaccharides, and polyols – types of fermentable, short-chain carbohydrates. For more on this, Monash University has a helpful app about FODMAPs.) If you have a digestive disorder such as irritable bowel syndrome, you might find that regularly consuming a low-FODMAP diet is very helpful. However, most people don't need a low-FODMAP diet for long periods - beginning as little as 24 h before a race until the event is over might help. Alternatively, a less restrictive option that works very well for some runners is just removing certain FODMAPs - for instance, only eliminating foods that are high in lactose (which is in many dairy products) and fructose (most sugars and fruits have lots of fructose).
    • For some people, reducing or eliminating irritants such as high doses of caffeine and gluten will also reduce digestive distress. If you tolerate these well, however, this strategy is unlikely to benefit you.
  • When you eat matters:
    • Most people have fewer digestive troubles and more of an appetite early in a day of running. You might want to slightly increase your calorie intake at this time to align with this.
    • If you are running through the night, your biological “clock” programmes changes in your body that hamper digestion and metabolism during the night, so eat what you can at this time but don’t force-feed yourself.
    • At times when you can’t stomach foods or drinks, consider rinsing your mouth with a carbohydrate drink. Receptors in your mouth detect carbohydrate and relay its presence to your brain. Through this mechanism, merely rinsing the mouth with a carbohydrate solution (not swallowing it) boosts performance in some types of exercise.
  • Medication matters:
  • Hydration matters:
  • Practice matters:
    • You should practice your race nutrition strategy in training for several weeks before the event. While as little as 3 race-nutrition practice sessions per week for 2 weeks can work well, if you're only including a single nutrition practice session a week then you might need as many as 10 weeks. This subject hasn’t been comprehensively studied, but it seems that when runners spend time getting used to consuming food during running, they substantially reduce digestive problems arising from eating while running and thereby enhance their performance. At minimum, try doing this just for a single session each week, and selecting the longest training session of the week to practice race-day nutrition is often a good option. It makes sense to try to build your tolerance during this phase: from one session to the next, try increasing the number of calories you take in per h of running. Your goal should be to consume more per h than what you'll consume during the race - by the end of these sessions, consuming 120% of your in-race nutrition is a good goal.
    • When practicing your race nutrition, it’s best to mimic the race conditions (pacing, terrain, temperature, time of day, etc) as closely as possible. For example, if you’ll be running in a very hot place, you’ll benefit from a period of heat acclimation. To maximise the benefits of heat acclimation, you'll probably need at least 14 days of heat acclimation. That doesn't need to entail living in the heat - exercise in the heat alone can suffice. Combining exercise and sauna use at this time might be a helpful strategy too. Basically, during heat acclimation, the important thing is to keep your core temperature high for extended periods (probably at least 100 mins or so per session). Conversely, if you're competing at altitude (say, 2000 m or higher), you might need 2 to 4 weeks of altitude acclimation to be at your best.
    • In the days before the event, consume many of the items you’ll have during the race.

Hydrate to dominate

There are several hydration mistakes athletes commonly make: 

  • During a run, staying in a state of optimal hydration will lead to weight loss. There are several reasons for this, one of which is that muscle glycogen depletion leads to weight loss. So, if you stay adequately hydrated on race day, expect to have lost at least 2 % of your bodyweight by the end of the day. If you maintain your weight while running, that’s likely not a good thing.
  • It is completely normal to urinate less during exercise than when at rest, and your urine will darken a little too - even if you stay well hydrated. 
  • Loads of runners drink sports drinks, but doing so can be problematic. One issue with these drinks is that have a fixed fluid: solute ratio, and it’s best to adjust this ratio according to your body’s needs.

Here are some tips to avoid these mistakes:

How to recover faster between days of multi-stage ultramarathons

If you’re competing in a multi-stage race, your goal should be to wake up no lighter than 1 kg less than you started the previous day and to then pass urine that isn’t dark - anything lighter than the colour of non-cloudy apple juice is likely fine. You’ll benefit from implementing the following strategies:

  • As you slow down at the end of the day or as soon as possible after you stop running, consume about 0.4 g protein per kg bodyweight and roughly 1.2 g carbohydrate per kg bodyweight. If practical, opt for the same high-GI, easy-to-digest carbohydrate sources you used to glycogen load before the race.
  • Drinking calories can be helpful at this time. If you’re trying to replenish your muscle glycogen stores, I like recovery drinks based on whey protein and carbohydrate powders. If you’re on a low-carb diet, smoothies made with Calm or Calm & Rebuild Long Range Fuel are ideal.
  • Continue to snack until shortly before you try to get some sleep. If you're on a high-carb diet, continuing to take in about 1.2 g carbohydrate per kg bodyweight per h until your final meal is a smart goal, and given the limits of your digestion, it's best to eat small amounts often at this stage. A 100-g pouch of Calm & Rebuild Long Range Fuel is a perfect snack at the end of the day.
  • Continue to drink to thirst. It's best to drink small amounts frequently than lots straight after exercise. If you drink lots of plain water immediately then even if you pass clear urine, you might remain under-hydrated (hypohydrated).

Supplements for ultramarathon runners

If you use supplements, you should base your strategy on your particular needs. For simplicity, I’ll break down some of the science-backed supplements into a few categories, beginning with performance enhancement.

Performance-enhancing supplements

Micronutrient supplements

If your diet is quite restrictive (e.g., if you’re on a vegan diet), you’re more likely to benefit from certain micronutrient supplements. For more on this, check out our free e-book, The Principles of Resilient Nutrition. The following supplements are particularly relevant to ultra runners.

  • Iron: Many athletes, and particularly women who have large menstrual blood losses, benefit from iron supplementation. Iron supplementation tends to be especially helpful when racing at altitude, for the elevation substantially increases iron needs as iron supports the synthesis of new red blood cells. In other instances, however, iron supplementation can actually be harmful. So, I wouldn’t supplement iron without medical supervision, and I won’t give iron dose recommendations here. If you do supplement iron, one thing to note is that some iron supplements regularly cause digestive distress. Chelating iron with the amino acid glycine can offset this problem and improve how well the iron boosts haemoglobin levels, so I suggest that people choose an iron bisglycinate supplement and consume it with a vitamin C-rich meal to enhance its absorption.
  • Multivitamin and multimineral: Because race-day nutrition tends to centre on heavily processed foods such as freeze-dried meals, race-day menus aren’t always particularly rich in vitamins and minerals. For this reason, I sometimes have ultra athletes I work with take a multivitamin and multimineral supplement, usually with breakfast. A food-based alternative is to use a powdered “greens”-type supplement containing a diversity of micronutrient-dense plants.
  • Vitamin C: Vitamin C is an essential nutrient that fulfils many roles, including several that are integral to immune function. While there are good reasons to think that long-term high-dose vitamin C supplementation could actually interfere with how you adapt to exercise training, short-term moderate-dose supplementation might slightly reduce your risk of upper respiratory tract infections. So, if you want to help keep the common cold at bay around your race, try supplementing with 250 – 500 mg vitamin C per day, beginning about 1 week before your race.

Immune system-boosting supplements

Doing the heroic volumes of exercise that ultra runners do may predispose them to upper respiratory tract infections, such as the common cold.

  • Probiotics: Certain probiotics seem to reduce risk of developing respiratory tract infections. To get this benefit, this you’ll probably want to begin supplementation a couple of weeks before your race. For a summary of the findings of studies on probiotic supplementation and exercise, check out this table.

Needless to say, consuming enough calories (especially from protein and carbohydrate) is key to immune function too!

Supplements for musculoskeletal resilience and gut health

I mentioned earlier that drugs that are commonly used to relieve joint have some undesirable side effects. Fortunately, there are some supplements that counter pain without these consequences. Of the different supplements shown to relieve pain in conditions such as arthritis, I particularly like the following:

  • Curcumin: Found in the roots and rhizomes of turmeric, curcumin has an extraordinarily wide range of beneficial biological effects, including potent anti-inflammatory actions in many tissues. Supplementing 500 mg twice a day with meals consistently reduces pain, swelling, and stiffness in arthritis. Curcumin also tends to reduce DOMS (delayed onset muscle soreness) and seems to support the integrity of the gut when exercising in the heat. One key consideration is that the optimal dose depends hugely on the bioavailability of the type of curcumin used. Initial approaches to increasing the bioavailability of curcumin products included adding piperine (a constituent of black pepper) or turmeric oil, and more recent methods include dramatically reducing the particle sizes of products.
  • Ginger: Some evidence shows that ginger might reduce pain and disability in arthritis. Although not all studies have reported these effects, ginger is safe, tastes great (gingerbread Long Range Fuel is my new favourite!), and does seem to produce several other relevant positive effects, improving digestive health and reducing feelings of nausea and vomiting, in particular. Try 1 g powdered ginger per day.
  • Glucosamine: Glucosamine is present in almost all tissues and is highly concentrated in connective tissues. Supplementing glucosamine sulphate (try 500 mg, 3 times a day) seems to slightly reduce pain and the rate of collagen degradation in arthritis. You might want to avoid it if you have shellfish allergies or asthma, or if you’re taking diabetes medications or warfarin.
  • Hydrolysed collagen (collagen hydrolysate): Hydrolysed collagen is collagen that has been taken from the connective tissue of non-human animals (e.g., cows or fish) and then broken down into smaller structures by heating it and adding enzymes. Supplementing with about 10 g collagen hydrolysate per day stimulates the synthesis of new connective tissue in joints, thereby alleviating pain. As vitamin C is essential to supporting forming new collagen in your body, take about 50 mg vitamin C at the same time for best results.
  • Undenatured type 2 collagen: Our bodies contain many forms of collagen. Type 1 collagen is abundant in tendons, ligaments, skin, bones, and some other organs. Type 2 collagen, on the other hand, is the primary constituent of cartilage, and supplementing with it helps keep pain at bay during strenuous exercise. If you try it, about 40 mg per day is a good starting point.

Supplements to speed recovery between days of multi-stage events

To be clear, several of the supplements I’ve already mentioned support recovery after running. Here are a couple more though:

Powered in part by Long Range Fuel, Claire Smith (affectionately known to her friends as "Brutal Claire") ran from John o'Groats to Land's End in 2020.

Nutrition and logistical considerations

Finally, if you’re new to ultramarathon running, there are some logistical factors you should consider.

Aid stations

At many races you’ll be able to pick up different foods and drinks at aid stations. Check your race information (ask the event organisers, if necessary) about what you’ll be able to get and use this information to choose what you take with you. If you plan to consume items available at these checkpoints, consider taking small bags with you so you can take items away to consume while running.

Drop bags and crew bags

Some races will allow drop bags and/or crew bags at points along the race.

If drop bags are allowed, pack them lightly with your preferred foods and drinks, as well as any other necessary supplies (e.g., clothing, footwear, a headtorch, first aid if not otherwise available). Many runners find that having a drop bag every 20 miles or so is ideal.

If you’re allowed crew at aid stations, they can carry a crew bag for you that contains some nice-to-have items that you’d not have in a drop bag. Some runners benefit from keeping packs or waist belts stocked with race fuel for the next part of the race at these points, for the runners can then seamlessly transition to the next stage. Have your crew collect these bags once you’ve used them, if possible.

Whatever bags you have, label them carefully (name, number, location) with a waterproof pen, and use durable bags with a waterproof outer casing, if needed. Don’t use trash bags, they’re not very resilient.

A key tip for self-supported runners

There’s one more tip I want to give self-supported runners: If potable water sources are limited, a water bottle with an inbuilt filtration system could be a lifesaver. There are several good ones out there, and I particularly like LifeStraw. (I have no affiliation with them, I just like their products!)

Conclusion

If you made it this far, you’re not just an ultra runner, you’re an ultra reader.

We covered a lot of ground in this article, and I hope it helps you cover a lot of ground at record speed!

The amount of information above might seem a little overwhelming, so please remember that you don’t need to make lots of changes to your nutrition at once. Instead, consider making a single change to begin, and approach your nutrition as an experiment: Try new things, have fun, and see what works for you!

If you do try some of the strategies we’ve covered, do let us know how you get on via our social media channels (Instagram)!

Run with resilience,

Greg

EnduranceNutritionRunningUltra Marathon
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