Nutrition for marathon runners: how to maximise performance

The Vitl Nutrition Team / 29 Sept 2021

The London Marathon is just around the corner..! Here's how to support your body with nutrition to help you maximise your performance and help protect your body from injury.


Running a marathon is the ultimate endurance test. Without the right fuel, it will be even harder for your body to perform and recover. Understanding nutrition as a training and performance tool is key to a successful marathon. When training for a marathon it is not just what you eat to fuel your body but when you eat, too. “Nutrient Timing” is the best way to maximise and maintain glycogen stores, which is where you split each 24 hours into 3 metabolic phases to fuel with macronutrients.

The 3 Phases of “Nutrient Timing” are...

1. Energy phase

When? 10mins prior to and during your training/race.

Studies have shown consuming both carbohydrate and protein together before, during and after can increase blood flow to the muscles, reduce glycogen depletion, and counteract dehydration.

This combination of nutrients helps to replenish muscle glycogen more rapidly than carbohydrates alone, therefore minimising muscle damage and allowing faster recovery. It also helps to support the immune system.

During exercise, food and drink should be easily digestible and well-diluted and you should aim to be consuming 60g-90g of carbs per hour.

It is recommended that you trial food and drink combinations in your training runs; do not try anything new in the race as everybody reacts differently.

Dehydration is the biggest pitfall for marathon runners. Runners lose approximately 1ltr of water per hour through sweat. Drink 2 glasses of water in the morning when you wake up and another glass before you leave the house. From 10mins before the race, you can start to drink sports drinks with natural sugars and electrolytes. It is better to take big sips at frequent intervals.

Always start to take in energy shortly after you start running. Studies show that taking on energy at 15-20 minute intervals is more effective than taking on the same amount after 2 hours of exercise.

2. Anabolic phase.

When? 30-45 minutes after your training/race. 

This is when your anabolic hormones help your body to be most effective at replenishing its stores of glycogen and the repair and growth of tissue.

Eat approximately 1- 1.5 grams of carbohydrate per kg of your body weight and 10-15g of protein within the first 30-45 minutes after your marathon training. E.g. For a 55kg person, 2 bananas (30g carb each) and a protein bar.

3. Growth phase

When? The remainder of the day: 45mins after exercise to 10mins before the next session.

As your anabolic hormones fall, it becomes important to focus on meals that contain smaller amounts of complex carbs (fruits, vegetables, beans, whole grains) and slower digested proteins (meat and fish, low-fat cheeses and dairy).  

Aim to meet your calculated daily carbohydrate requirements and 20g of protein per meal.

Make sure you are eating enough! On the day of the race, breakfast is particularly important as your glycogen stores will have diminished overnight.

Don't forget...


High levels of physical activity lower immunity and increase oxidative stress so it is important to support these systems not only with ‘food as fuel’ (macronutrients) but also with food to support function. This is where micronutrients - vitamins, minerals, antioxidants, polyphenols and fatty acids - come in.

Energy is what powers you through your runs. B vitamins are particularly needed for the energy production process so a deficiency may impair both aerobic and anaerobic exercise performance.

To combat injury and illness brought on by oxidative stress, aim to obtain high levels of antioxidants through your diet. Glutathione is the 'mother of all antioxidants' and is produced by the liver. You can improve your production of glutathione with green tea and turmeric.

CoQ10, berries, and super greens also contain antioxidants which help reduce the risk of damage from oxidative stress and can potentially reduce muscle recovery time.  

Your joints! 

It is well-known that high impact sports like running can cause joint problems later on in life. Omega 3s found in krill oil, and turmeric and ginger all are potent anti-inflammatories and have been shown to have a positive effect on joint health.

Inspired and going to train for the marathon next year? Take your consultation now, to make sure you get nutrients tailored to your athletic needs to support your marathon performance!