The Runners Guide To Carbohydrate

5 reasons runners should be eating carbs – even if their purpose for running is to lose weight. In fact, especially, if their purpose for running is to lose weight!

Carbohydrates are the body’s main source of energy and vital for runners as part of the overall “athletic development plan”. Typically they should make up around 33% of your diet. 

Often, carbs are referred to as one entity, however it is important to appreciate that there are three different types of carbohydrates; sugar, starch and fibre. Each plays a different, and important, role in a balanced normal diet. Starch is the key carb for runners to consume as it provides a slow release of energy throughout the day. Starch is readily available and can be found in many common foods; bread, rice, potatoes and pasta.

Sadly (and annoyingly!) many popular diets advise cutting out carbs from your diet to lose weight, trying to force the body to break down stored fat by removing (or drastically reducing) the readily available glucose from metabolising carbohydrate. However, metabolising body fat (which is of course a normal process), increases “ketones” in blood, causing ketosis, and decreases sugar levels in the blood, potentially causing hypoglycemia. These conditions can result in headaches, weakness, nausea, dehydration, dizziness and irritability. And whilst runners do not want to carry more weight than is necessary (think hills!), cutting carbs is an even bigger mistake than doing so in the general population. In addition to the symptoms just mentioned, low blood sugar in a runner will lead (at best!) to an inability to train effectively, will increase recovery time (again leading to a degradation in training effectiveness) and at worst collapse. 

During exercise, your body relies on your glycogen stores in your muscles which can quickly run out (typically around 20 mins but this will vary between runners) during mid to high intensity endurance sports. Depletion in glycogen can result in tiredness and a lack of energy. Topping up on your carbs during exercise through gels, chews, bars and drink mixes can prevent energy levels from dropping mid-exercise and therefore help you complete training sessions at the required intensity.

As a guide, the recommended carbohydrate intake for endurance athletes is 6-10g per kg body weight, per day so an athlete weighing 70kg should consume 420-700g of carbs during one day.


1) Increased energy & prevents fatigue

When carbohydrates are ingested, the body will convert them into glucose which is used as a fuel to provide energy. During exercise, your energy source comes from the glycogen stores in your muscles and Liver, which can cause tiredness and fatigue when these stores become depleted.

Carbohydrate-electrolyte drinks can increase your endurance performance as well as improve lactate removal which in turn delays the onset of fatigue. Ideally carbohydrates should be taken during exercise at a rate of 30-60g per hour (but again this will vary and tolerance needs to be built up during training). Conveniently (and not by accident!), most energy gels come in sizes from 30-60g making them perfect for carbohydrate consumption during exercise. Consuming carbohydrates during moderate intensity exercise has proven very effective. It is not required during low intensity sessions,  and whilst beneficial during high intensity work in practice can be problematic.

2) Improves performance

During moderate to high intensity exercise lasting over 2 hours, consuming carbohydrates can significantly improve endurance performance. Even for athletes involved in team sports such as football, rugby, tennis, cricket and netball, carbohydrate ingestion has shown to greatly benefit their performance. So whilst I am mostly concerned with Endurance Runners, the value of Carbohydrate is clearly much broader.

For runners taking part in runs lasting 2 to 3 hours, it is advised to consume 60g of carbohydrates an hour, to maximise oxygen glucose oxidation rates in the blood which helps support metabolism. While well-trained endurance athletes completing races longer than 2.5 hours can consume up to 90g of carbohydrates an hour, providing it is taken in several smaller servings and the body as been conditioned during training to tolerate this disage.

3) Prevents Hypoglycemia

Hypoglycaemia is the drop in blood sugar levels that usually occurs after the body produces too much insulin. Symptoms of low blood sugar includes dizziness, tiredness, feeling shaky or trembling, heart palpitations, and if left untreated can lead to confusion, sleepiness, passing out, and even seizures or fits. Carbohydrates can prevent and greatly reduce the risk of getting hypoglycaemia, and be can be taken through carbohydrate snacks such as toast, or through carbohydrate drink mixes like Tailwind Endurance Fuel Drinks.

4) Reduces the risk of heart disease

To lose weight, many diets will advise cutting out carbohydrates from your diet altogether (or drastically reducing them), however this comes with risks. Weight loss is solely dependant upon achieving a calorific deficit, so cutting carbs will reduce calories and therefore ‘work’. But at a price. In these diets, carbohydrates are typically replaced with fats or proteins with high fat contents, which will cause your body to use stored fats for fuel instead of the glucose you get from carbs. However, by increasing your intake of saturated fats, you are also raising the cholesterol found in your blood. The high saturated fat and high cholesterol levels can lead to heart disease or strokes. Fat also contains twice the calorific value per gram compared to carbs, and therefore it is much easier to over consume calories when eating high fat foods, as the portion size appears relatively small.

These high fat, low carb diets have shown to provide short-term solutions for many people in losing weight. When advised by a qualified Dietician the health benefits can outweigh the risks. However, Google is not a qualified Dietician! And for the majority of people, and particularly runners a low carb diet for weight loss is likely to be inappropriate. 

Consuming carbohydrates as your source energy instead of fat will decrease your risk of heart disease. Eating a balanced diet of 1/3 carbohydrates, 1/3 fruits and vegetables and 1/3 dairy and protein, staying active and reducing sugar consumption will also help prevent heart disease. Eating a plant-based diet with a carbohydrate base, there is a significantly lower chance of developing heart disease, diabetes and obesity. Ultimately you just can’t beat getting the basics right. 

5) Aids in repair & recovery:

The two hours after exercise are the most important hours during the recovery process. Rebuilding glycogen levels and replenishing electrolytes are most effectively done during this “opportunity window” (7) and helps increase recovery time. Post-exercise is the best time to consume a meal or snack filled with carbs such as bread, pasta, rice, lentils, beans and potatoes.

It is essential to remember that carbohydrate intake will differ from person-to-person depending on gender, age, weight, exercise intensity, length of time exercising, and current diet.

You may know that I also own – If you are looking for energy products that work super well for runners (in fact were designed by runners for runners!) – take a look at our range of Tailwind Energy Fuels.

Join my mailing list!

Subscribe to my mailing list and join over 2000 multi-sport athletes who receive free training articles, event updates and special offers by email.

You can change your mind at any time by clicking the unsubscribe link in the footer of any email you receive from me, or by contacting me by email. I will treat your information with respect. For more information about my privacy practices and policy please visit my website Privacy Policy. By clicking the link above, you agree that I may process your information in accordance with these terms.


Join 3 other runners & triathletes and be the first to see useful content, news and the occasional offer.

Unsubscribe at any time. I usually send two emails a month.

View more articles
  • Running Injury Risks

    There are numerous health benefits to running, but of course it also carries an inherent degree of injury risk. Most injuries arise from overuse rather than trauma. Broadly, there are three main categories of risk considered to cause running injuries: biomechanical factors, anatomical factors and training error. Over the course of the next few blogs…

  • Why is slow running so damn hard !?!

    It is one of the more infuriating and counter intuitive aspects of run training, the reality that slowing our run pace down feels so much harder than we imagine. It just shouldn’t be the case should it, yet I am guessing that you too have experienced this phenomena. When the newbie runner first starts in…

  • Worry About What You Can Control

    Focus on the variables you can control. Whist this is tried and tested advice, should we just ignore the uncontrollable factors? Better is understand the opportunities some of these factors offer and then take advantage to improve our plans.