Ultra marathons tend to be run slower than a typical road marathon. With ultras you are out there working for longer, which means you do need to pay close attention to your fuelling and hydration. A common finding from runners is believing that with a slower pace they don't need as much nutrition.

What are the nutritional recommendations?

When it comes to endurance nutrition, carbohydrates are king as they are the body's preferred source of fuel. Even our brains need around 130g of glucose a day just to function! Our liver and muscles will store glycogen, which is an easy (but limited) store to tap into when we need energy. Empty your glycogen stores and you will have likely experienced 'hitting the wall' or 'bonking' during a race. We have around 90–120 minutes of stored energy available for high-intensity work like running. The faster you go, the quicker you deplete these stores. You must therefore ensure the body gets a regular supply of energy from carbohydrates to avoid emptying stores.

The current recommendations for carbohydrate intake during endurance exercise are as follows*:

  • Up to 1 hour – Nil, unless it's been some time since your last meal/snack or you're doing high-intensity work. Or of course if you feel you need it.
  • 1–2.5 hours – 30–60g of carbohydrate per hour
  • 2.5 hours or more – Up to 90g of carbohydrate per hour, from multiple carbohydrate sources

These are of course just guidelines. Nutrition is personal and what works for one won't necessarily work for the next. Factors such as body weight, workout intensity, gut tolerance, heat and duration of run will influence energy and carbohydrate needs.

Should I eat real food, or stick to sports products like gels?

Whilst you can use exclusively one or the other over an ultra-distance, this can be trickier due to taste fatigue and gut tolerance. Generally, I find many runners like to use a mix of the two, myself included. Often with ultras you can be out all day (and night), so having some normal foods at usual mealtimes can help stick to normal circadian rhythm. It also helps add structure to your intake – e.g. you may want to have a 'lunch' option, so something like a jam and peanut butter sandwich or a cheese and crisp roll all work nicely. Of course, you should practice these things in shorter training runs to see how your gut responds.

How can I stop it being boring?

Opt for a mix of foods, sports products and drinks to keep things interesting. Real food also provides a variety of textures from crunchy and crispy to soft or chewy. Mixing up between sweet, savoury or salty foods can also help. If you struggle to eat as much, using a carb-based drink can help keep your intake topped up. When it's hot out, cooling foods and drinks can also be helpful. When I did the Moray Coastal Ultra 50 in May 2025 during a heat wave I was craving ice lollies – I was lucky my friend followed me around the check points and handed out mini Calippo's! They were a game changer: they helped cool me down and provided ~20g of carbs each. Far more appeal at that time than a gel! Equally, if you're going out in cold temperatures, a hot sugary drink, flask of soup, or instant noodles can be winners. This is where you want good crew to prepare and provide these things!

So, what are the best foods to eat?

The best foods to eat are the ones that you enjoy and will actually eat! You can test things during training runs and see what works. Some runners like to keep certain foods as 'treats', something to motivate them to the next check point. Having some of your favourite foods can really help if your mood has dipped. Knowing I had a cheese and pickle roll waiting at mile 26 of my ultra was motivating; it was also my usual lunch time, so helped keep things structured.

Is there anything I should not eat?

There are some foods where I would suggest exercising caution. For example, anything too fibrous, fatty or 'sugar free'.

Fibre takes a while to digest and can potentially cause gut discomfort – keep your fibre for normal healthy eating to keep your gut healthy and avoid too much during an event.

Fat slows down digestion and can often stimulate bowel movements causing diarrhoea. We need more carbohydrates for energy during an event, so whilst a little fat is ok, avoid too much.

The reason I say avoid 'sugar free' products is that some are full of artificial sweeteners; these can be disruptive to the gut and many have a laxative effect. They're also not providing you with any form of nutrition. I remember seeing a runner guzzle a can of Diet Coke during an ultra once – all that gas and no carbs. Save those for non-race days. Always practice, practice, practice and get your gut sorted. There's a reason the phrase 'don't try anything new on race day' is commonly said!

Common problems for ultra runners

A common reason for DNFs in ultras is poor nutrition and hydration strategies, often leading to gastrointestinal symptoms which for many can be avoided or minimised. Nausea, stomach cramps, belching, wind and diarrhoea can all occur and can have a negative impact on performance as well as ability to take on further fuel.

When you train, you also want to train your gut – it is a muscle and will adapt. You don't even have to wait for your long run to practice taking on nutrition; shorter, smaller or easy runs are all great times to experiment. That way, come race day you know what you like and what works. Also, the more you fuel in training, the more your gut can handle, meaning you're able to take on board more energy and have the best chance of completing your race.

How can I manage my fuelling?

Practice during your training and then devise a plan for race day. It's easy to get caught up with the excitement and forget to fuel (yes, I've been there myself). It is best to start early and take on something even before you think you need it. Having something small every 20–40 minutes can be helpful. You want to try to keep energy levels steady and avoid depleting your glycogen. You can even set nutrition reminders on your watch to prompt you.

When you train for your ultras, don't forget to train your gut too!

* Burke LM, Hawley JA, Wong SH, Jeukendrup AE. Carbohydrates for training and competition. J Sports Sci. 2011;29 Suppl 1:S17-27.