Ultimate Marathon Preparation Guide

School Of Nutrition Posted Apr 14, 2014 Future Fit Training

If you want to avoid ‘hitting the wall’ and learn inside tips to maximise your energy and stamina through good nutrition, look no further.

Ultimate Marathon Preparation Guide

Optimal nutrition in the run up to an endurance event is as crucial as a good training programme. 

Vital Fuel:

Around ¾ of marathon runners cover the second half of the race at least two minutes slower than the first, many slowing even more dramatically after the 20-mile mark, where the ‘wall’ traditionally awaits! The most common cause of hitting the wall is muscle glycogen depletion.

Glycogen is the reserve form of carbohydrate stored in the liver and muscles and is used for energy when the body needs more glucose than is readily available in the bloodstream. This is exactly what happens during endurance exercise. The body can store around 2000 calories worth of glycogen and around 80% of this is stored in muscles.  Optimising glycogen stores beforehand and replenishing them effectively afterwards is the key to success.  

At least 60% of your calories during a marathon training programme should come from carbohydrates. As the event nears this need increases further.

Carbohydrates act as the body’s primary fuel: Carbohydrate requirements can be calculated for an individual training for a marathon depending on their average daily e.g. 7–10g CHO / kg bodyweight daily based on daily 90-120 minutes activity.


Nutrition TipDay to day during your training programme, opt for slow release, fibre rich carbohydrates such as brown rice, oats, quinoa, wholemeal pasta, wholemeal bread, sweet potatoes, pulses (beans and lentils) and fresh fruits and vegetables.


Energy In, Energy Out

Serious marathon runners will want to aim for their optimal racing weight because excess body fat is dead weight that increases the energy cost of running. Generally for endurance runners the ideal falls near the bottom end of the healthy BMI range i.e. 18.5 – 21.7. Studies have shown that a typical runner who sheds just one pound of body fat could see a one-minute improvement in his or her marathon time without any change in fitness.

If weight management is not an issue then remember that during training, you will generally expend around 100 calories per mile you will be running so you need to replace this additional energy lost.


Nutrition TipBeware of what is known as compensation effect. The natural appetite increase that comes with high levels of exercise.  You can’t just ignore your additional need for fuel but ensure you consume nutritious foods, not just processed empty calories! Base your diet around vegetables and fruits, nuts and seeds, whole grains, lean meats, fish and dairy.


The Importance of Timings

Planning your Nutrition schedule to optimise your event preparation is key. Three days before the race, carbohydrate intake needs to be further increased to at least 70% of daily calories to maximise glycogen storage and energy reserves for your marathon.  Alternatively you can calculate it as follows: 8-10g/kg-body weight e.g. 70kg person requires around 600g / day carbohydrate.


Nutrition TipOn the evening before the event: eat around 200g of carbohydrate (CHO), by basing your meal around brown rice or wholemeal pasta with a moderate amount of protein and a limited amount of (healthy) fat. If the volume of food seems overwhelming, eat small regular portions every couple of hours. E.g. 300ml Lentil Minestrone Soup, (40g CHO), 125g brown rice with 100g salmon fillet, 80g sugar snap peas, 50g spinach and 100g low fat tomato pasta sauce (110g CHO), 125g fruit crumble with oat topping and low fat custard (50g CHO).  


Race Day:

2-4 hours before the run try to eat a high carbohydrate, low GI and easily digested meal. Aim for 2.5g CHO / kg bodyweight. E.g. 70kg person = 175g CHO 

Ideas for pre-race breakfasts:
- Whole grain breakfast cereal with skimmed milk, fruit, toast and juice
- Muffins or crumpets with fruit, yoghurt
- Scrambled eggs, baked beans & wholemeal toast
- Rolls and sandwiches with low fat filling, yoghurt, and fruit
- Fruit smoothies or fruit flavoured yoghurts

Try to include a high carbohydrate, medium-high GI snack or drink 1 hour before the race for an extra boost of energy to help delay fatigue.

Pre-race snack ideas:
dried fruit, low fat fruit yoghurt, cereal or energy bar, wholemeal jam sandwich or a sports drink.

During the race: begin topping up carbohydrate levels after around 45 minutes  and aim to consume around 50g CHO per hour of the race

Ideas for during the race:
energy bars and gels, bananas, dried fruit, jelly sweets,  isotonic sports drink, diluted juice and smoothies.


Nutrition TipGlycogen becomes deplete as you burn energy and you need to top up your blood glucose levels with extra carbohydrate: It takes around 45 minutes for high GI carbohydrates that you’ve eaten to be utilised as energy. So keep ahead of the game, pre-empt your energy decline: don’t wait until feeling ready to collapse!


After the race aim to consume 1g / kg bodyweight of high GI carbohydrate within the first two hours and then 50g of any GI carbohydrates along with some protein 2 -4 hours post race.  Ideas that supply 50g carbohydrate:

­  200ml orange juice and 2 slices raisin bread

­  1 medium banana and pot of low-fat custard

­  30g Cornflakes,1 medium banana and 200 ml low fat milk

­  2 medium slices toast, 2 teaspoons jam and 200ml skimmed/semi-skimmed milk

­  100g grapes, 2 fig rolls and 150ml dilute squash

­  Lean ham and salad sandwich (2 slices brown bread) and 200ml apple juice

­  175g baked potato (with filling e.g. salad and prawns)

­  150g pot low-fat yoghurt, 2 Digestive biscuits and 150ml apple juice

­  1 crumpet and a teaspoon of jam and 500ml isotonic sports drink

­  300g home-made fruit salad (with equal proportions of banana, orange, apple, pear and grapes) and 150g low-fat yoghurt

Hydrate & Rehydrate!

As well as food for fuel, good hydration status is of course essential to your training and marathon success.  Dehydration by as little as 2% of body weight can hinder your performance and in extreme cases dehydration could contribute to collapse or even death during a marathon. Whilst following your training programme you should be aiming to drink around 1ml of fluid per daily calorie burned. e.g. 3000 kcal / day = 3 litres of fluid.

Drink 500ml – 1L of fluid two hours before the race allowing you to build hydration and then top up with 250 - 500mls of fluid 15-20 minutes before the race starts.

During the race top up hydration steadily and regularly to help maintain both physical and mental l performance. Aim for around 150ml every 15 minutes. 


Nutrition TipPractise drinking while on the run in preparation for the big day, this will help you get used to the physical co-ordination of doing the two things at once and help to reduce stomach upset during the race.


Following your race you can calculate fluid loss by weighing yourself and comparing your weight to pre-race weight. For every kg you have lost it indicates a 1 litre loss of fluid. Fluid loss should be replaced by 150% to allow for that which will not be absorbed.

Sports drinks – are they necessary?

Research has shown that sports drinks have no effect on performance in runs lasting less than one hour. However during a longer run like a marathon they can be an invaluable way to not only rehydrate but also replace electrolytes lost in sweat, take in easily digested carbohydrates that are absorbed at the highest possible rate and enhance performance by maintaining blood glucose levels and delaying muscle glycogen depletion.

Nutrition TipYou can make your own isotonic sports drink at home by simply combining 50% pure fruit juice with 50% water and a pinch of salt. This could save you a lot of money as your training programme with longer runs intensifies.


Whether a first time marathon runner or a seasoned professional  hopefully our Marathon Nutrition guide and tips will give you insight and ideas that support your success and make that 26.2 miles seem that little bit shorter.

Happy Running!   

Written by Becki Douglas



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