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the marathon series - Kim's nutrition

What do I eat if I want to train for an ultra-marathon?

Training for the comrades is no joke.  It’s hard work – those endless hours of training spent on the road – you need strength, endurance and stamina, as well as good nutrition and hydration.  Is there even time for a life?  Nutrition and hydration of course plays a major role to ensure that you have the energy available to do all the necessary training without having burnout or getting sick!  Let’s take a look at what this entails and what you should focus on to ensure that you can put your body through the preparation.

Your day to day diet

One of the most important things to work on is to ensure that you eat enough in your day to day life so that you have energy for the training.  You can get energy from carbohydrates, proteins or fat.  Each of these food groups play an important role in our bodies and should be incorporated into your eating plan.

Carbohydrates are the best source of immediate energy (although there are those that will disagree with me), and are the largest contributor to the energy needed during exercise.  They fill up the muscles with glycogen – the storage form of carbohydrate that is used first during the exercise periods.  Once this energy is used up your body relies on blood glucose (which it can get from any of the food groups).  As exercise becomes more intense, carbohydrates contribute mostly to the energy supply. 

Generally speaking, long distance runners need between 7 and 10g of carbohydrate per kilogram body weight during the intense training periods.  This is a lot of carbohydrates.  For example, for a 60kg person, that would equate to 420-600g of carbohydrates.  In carbohydrate servings, which is a bit easier to understand, this is 28-40 servings (see ideas for servings below).

Examples of 1 carbohydrate serving = 

  • 1 cup (250ml) milk
  • 175ml plain yoghurt
  • Tennis ball size fruit or 20g dried fruit
  • ½ cup cooked legumes, starchy veg or starch
  • 1 slice bread
  • 3-4 crackers
  • ¼ cup muesli or ½ cup all bran etc.

When you think of eating 28-40 servings of these foods (and possibly more if your weight is higher) it feels like a mountain of food.  It is because of this that we often suggest using fluids (such as fruit juice, smoothies or sports drinks) to get the carbohydrate quantity up as it is often easier to drink calories, especially when the appetite is down due to the excessive exercise.  It is of course important though that we eat a reasonable amount of food in the ‘better nutrient’ form (for example whole-grains vs white) to ensure that you get the vitamins and minerals that your body requires. 

Fats can also contribute to the energy needed for exercise, however, as the exercise becomes more intense fat is less available as the conversion of fat to energy is slower than carbohydrate. If you are running along at a slow consistent pace, your body can tap into these fat stores nicely to keep you going, but the minute you want to sprint a short distance you will feel flat if you are not eating carbohydrates.

Fats plays many important roles in our body.  Aside from an energy source, they support cell growth (every cell is made up of fat), play a role in hormone production, help our body absorb fat soluble vitamins, protect our organs, and keep us warm. 

Runners therefore need 20-35% of the total calories to come from fat.  The best fat choices are those that come from plants, such as nuts, seeds (as well as the nut/seed butters), avocado and olives, and any foods that contain these for example hummus, pesto, and oils, as well as fatty fish.  Fats from other animal products should be used in moderation.  The fats that you want to avoid is the cooked plant fats (these are seen in products such as fried and baked goods).

Fats are very energy dense, so the amount that needs to be added to the meals is not a lot. Half an avocado, a couple of tablespoons of hummus or a small handful of nuts or seeds are adequate to add to a meal or snack.

Protein does not contribute to a lot of energy during exercise (only about 5%), as long as you are eating enough energy overall.  When your body runs out of energy from carbohydrates and can’t tap into fat stores, protein will be used.  Protein however does start supplying energy during rest as it is needed for muscle recover and to help refuel the glycogen stores. 

The amount of protein endurance athletes require is 1.2-1.4g per kilogram body weight.  For our 60kg person this would equate to 72-84g.  This would be roughly 10-12 servings of protein (see ideas for servings below), which is not very difficult to get to in our Westernised diets.  Protein shakes can also be used, especially if you are struggling to eat due to loss of appetite.  Generally a serving of protein shake is equivalent to 3 protein servings.

Examples of 1 protein serving = 

  • 1 cup (250ml) milk
  • 175ml plain yoghurt
  • ½ cup cooked legumes
  • 30g fish, shellfish, chicken, meat, organ meat, cheese
  • 1 egg
  • ½ cup tofu 
  • Roughly ½ piece of meat alternative (e.g. Fry’s)


Micronutrients (vitamins and minerals) are very important in everyone’s diet, but they are especially important in the runners’ (and any exercisers’ actually) diet as exercise produces free radicals (this is because more oxygen is used and more food is oxidized into energy during the exercise).  Antioxidants from food help to neutralise these free radicals so they cannot cause damage in our bodies.  Fruit and vegetables are one of the best sources of antioxidants. Runners also need lots of other minerals such as zinc, iron, manganese and copper.  As an ultra-distance runner you should consume at least 8-9 servings of fruit and vegetables as well as wholegrains, fortified breakfast cereals, low fat dairy, fish, chicken, meats and plant fats.  Fatty fish are vital in the diet as they help fight inflammation as well as boost immunity.  It is therefore ideal to have at least 2 servings of fatty fish per week for a good dose of omega-3.

Is it time for you to step up your nutrition?

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