Ultra marathon nutrition is a highly individual thing. Some people prefer sports nutrition. Some people swear by real food. A few highly trained, fat-adapted athletes appear to be able to get by on a handful of nuts and seeds.
Whatever your preference, a good nutrition plan will make a huge difference to your performance in an ultra marathon.
In this article, we’ll describe the principles for developing your nutrition plan for an ultra marathon and provide a sample plan for a 100km trail race.
There are a few simple principles for ultra marathon nutrition. When you understand these, you can start to develop and practise with your own tailored plans.
1 Energy Expended When Running
A typical, reasonably well-trained 70kg runner will use around 100 calories per mile.
A rough calculation for your calorie burn is 1.39 x your weight in kg. [Ref 1]
At a target pace of 10:00 min/mile (this is a “competitive” pace but it keeps calculations easy), this is around 600 calories per hour.
1 Expected Effort Level Based on Course, Terrain and Target Pace
Your effort level will dictate how quickly you burn calories and the ratio of calories that come from carbohydrates versus fats.
Consider someone who runs at an easy pace of between 8:00 and 8:30 min/mile in training. If they set a target pace of 10:00 min/mile for the course, this will be a reasonably comfortable level. At this level of effort, they’ll be getting 50-60% of their energy needs from fat and 40-50% from carbohydrate.
Well trained runners can increase the proportion of energy obtained from fat. This is useful, because the body stores much more energy in fat than in carbohydrate. But don’t forget that the body still needs available carbohydrate to use the energy stored in fat.
3 Amount Of Energy That Can Be Comfortably Consumed
General guidelines state that most people can comfortably absorb around 60-90g of carbohydrate per hour. This varies based on intensity of effort and the type of carbohydrates consumed.
The 90g figure is based on consuming different types of carbohydrate, mainly glucose and fructose.
The amount of carbohydrate you can absorb appears to be a pretty static figure and independent of normal factors like body weight, gender, and training level.
4 Hydration Needs
A good starting point is to assume 500ml of fluid per hour. Most people find that drinking more than 1000ml an hour gets uncomfortable and leaves them feeling bloated. Actual needs vary greatly from individual to individual. They also depend strongly on the weather conditions.
Adding electrolytes, particularly salt and magnesium, has multiple benefits. Firstly, they generally make the drink taste better, encouraging you to drink more. Secondly, they can reduce the risk of cramp. Thirdly, they can reduce the onset of fatigue.
In ultra marathons, it’s often easier to consume calories from food, gels, bars, etc. However, energy drinks can play a role too. Drinks with carbohydrate and electrolyte, like SiS GO Electrolyte can be useful and convenient.
5 Ergogenic aids
Ergogenic aids are supplements or substances that enhanced athletic performance. We are only interested in legal and effective aids. Caffeine is the main egogenic aid for ultra marathon performance that meets these criteria.
Caffeine is one of the most studied substances for enhancing performance in endurance events.
Caffeine has been shown to increase performance between 5-10% in most athletes.
Taking too much caffeine can increase the risk of muscle cramps.
Therefore, in ultra marathons, the best way to use caffeine is to save it for later in the race. Taking it too early increases the risk of muscle cramping and means that the benefits wear off before you most need them.
In an event lasting longer than around 8 hours, this means that you probably want to save the use of caffeine until at least halfway through the race. A reasonable aim is to consume around 1mg of caffeine per kg of body weight per hour.
6 Food Type Preference
This plan is based on sports nutrition products. Using sports nutrition has a few benefits:
- Sports nutrition products tend to weigh less than equivalent real foods.
- The types of sugar tend to be more easily absorbed by the body than real foods.
- The nutrient content is more closely controlled. This means that you can be more confident about how much you are consuming.
- There may be a placebo effect of using products that are designed to enhance performance.
The downsides of sports nutrition products are:
- They can be expensive compared to real food alternatives.
- It doesn’t feel as natural and can diminish the experience for some people.
- Some people don’t enjoy the taste of sports nutrition compared to real food alternatives.
- Real food can feel more comforting. Let’s face it when you’re flagging, what would you rather have: an energy gel or a bag of chocolate raisins, a pork pie or a lovely flapjack (Chia Charge flapjacks kind of allow you to get the best of both worlds, but that’s another story)?
One other consideration with food is that generally, it’s better to use solid foods earlier in the race and save sweeter, softer foods until later in the race.
There are two reasons for this.
Firstly, energy gels and chews can give you stomach problems if you take too many too early.
Secondly, solid food is harder to digest and in the later stages of the race, your body will be less able to cope with solid bars and foods.
Putting It All Together
Bearing all of the above in mind, here is a sample nutrition plan based on using sports nutrition products.
This plan is based on the Race To The Stones. This is a 100km point-to-point race along the Ridgeway National Trail. It’s a relatively flat course, with around 3000 feet of total elevation gain. It’s a net uphill route.
References & Credits
If you’ve got other ideas, experience or tips, we’d love to hear from you.
- Do you prefer sports nutrition or real food?
- How much fuel do you take on during a long race?
- Any other tips or experiences you can share?