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Why is it important to fuel ahead of a run?

Ahead of a run or any workout, it is important to consume food in order to fuel the body with energy for your exercise bout through an increase of adequate glycogen stores. In turn, this has been shown to delay fatigue onset, reduce the rate of perceived exertion (how hard you feel your body is working), and increase exercise capacity (Albert, 2015; Jeukendrup, 2014).

With periods of high energy expenditure, going through long periods of underconsumption may lead to a variety of negative physiological and psychological processes including an increased risk of fatigue, prolonged recovery time, loss of muscle mass from a decrease in protein synthesis, an increased risk of illness or illness, or menstrual dysfunction. Relative energy deficiency (or RED-S) could be initiated through both intentional or un-intentional means, so as an athlete support personnel, it’s important to look out for any changes in body composition, increases in training load, reduction in performance, or an increase in tiredness in everyday life. Read more about the effects of RED-S here

But I've heard fasted training is good for me. Is this true?

When we look at the fuels that our bodies use to fuel our physical activity, we predominantly use both carbohydrates and fat. Compared to fat, we only have enough stored carbohydrates for around 90 minutes of high-intensity exercise. With this, there has been an ongoing argument that if we are able to increase the contribution of fat to our exercise regime, we could reserve our carbohydrate (glycogen) stores and increase our performance.

 Although studies have found that undertaking an endurance training session fasted (and by fasted, we mean that the body has been unfed for AT LEAST 8 hours e.g., a recommended sleep period) can enhance metabolic and cellular responses needed to increase the oxidation of fat, research has yet to show that these adaptations translate to an increase in performance. Although the opportunity for metabolic flexibility is still a fruitful area for research, with periodised carbohydrate intake potentially achieving a state of ‘metabolic flexibility’, it’s important to consider that fasted training shouldn’t happen all the time, as this could lead to muscle breakdown, reduced recovery, and mood suppression. Do what works for your own body. Some find that eating early before sessions can cause mental stress and gastric upset, so where training intensity and duration may not require significant input from metabolism, fasted training may be warranted.

What are the best things to eat before a run?

To push yourself within your workouts and progressively overload within sessions, it's vital that you are fuelled appropriately. Carbohydrates are the primary substrate for fuelling moderate to intense exercise bouts. With this, you should aim to consume a high-carb snack/meal 1-4 hours before (ACSM, 2016). Opting for foods with minimal fat, fibre, and protein has been shown to suit most, as these have been shown to slow digestion and absorption, leading to gastrointestinal issues (e.g., nausea, vomiting, belching, heartburn, bloating, cramps, diarrhoea; Jeukendrup, 2007). Liquid carbohydrates may also be a good option for those who struggle with consuming whole food before a training run. Everyone should incorporate an individual approach to what specific foods they should be consuming, as both preference and tolerance vary. Nevertheless, suitable, and easy snacks/meals include:

1 Bagel and 2tsp honey (65g carbohydrates)

5 dried apricots and a cereal bar (35g carbohydrates)

Lucozade sport (30g carbohydrates)

Smoothie and a medium banana (75g carbohydrates)

1 small bowl of cereal (30g carbohydrates)

1 small porridge serving (25g carbohydrates)

1 small juice carton (20g carbohydrates)

How long should you leave between eating and running?

In terms of timing, consumption has been recommended to be between 1-4h before your training run (ACSM, 2016). This is again, down to the individual, so it’s super important to incorporate a trial-and-error approach to figure out your own toleration level. Pre-planning is super important to help with adaptation and optimal performance! Practice well in advance of any important races to find what is best for you as an individual.


We have worked with hundreds of clients who are wanting to get their intake nailed consistently, and most importantly - sustainably. Book your free consultation today to get started!

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