Are carbs really king of the food castle?

Discover the role that carbohydrates play in fuelling exercise and fitness training

Range of different foods spread out on table
Range of different foods spread out on table

Are carbs really king of the food castle?

7 minute read

In the intricated interplay of health and athletic performance, one nutritional component stands out– carbohydrates. This macronutrient serves as the body’s primary energy source, playing a pivotal role in fuelling exercise performance. But what crowns carbohydrates the king of nutrients for the pursuit of optimal health and performance?

How our bodies consume carbs

In conjunction with protein and fat, carbohydrates make up one of the three primary macronutrients in the diet. These nutrients are all necessary for optimal health and wellbeing, but also for athletic performance. The body depends on glucose and therefore uses carbohydrates as its primary energy source. Glucose is produced when carbohydrates in food are broken down, providing fuel for organs like the brain and muscles. Eating adequate carbohydrates is therefore essential for maintaining overall health as well as maximising sports performance. Through a process referred to as gluconeogenesis, the body can produce glucose from other foods, such as protein, but this is not the best way to power performance.

The process of glycolysis, where carbohydrates are broken down to produce the body’s energy currency (adenosine triphosphate, or ATP), is the quickest way to generate energy for muscular contraction. Glycogen, the storage form of carbohydrates in muscles and the liver, serves as a readily available reservoir of energy during exercise. Adequate glycogen stores are crucial for delaying fatigue and maintaining performance.

Simple and complex carbohydrates

Since simple carbs only include one or two strands of sugar molecules, the body may easily convert them into glucose. Simple carbohydrates can be found in milk, honey, fruit, and sugar. Simple carbohydrates are thought to be better absorbed when ingested close to an activity session because they digest more quickly and can restore muscle glycogen after an exercise session or fuel performance beforehand.

healthy carbohydrate foods

Most of the carbohydrates in your diet should be complex carbohydrates. They are present in foods like rice, pasta, potatoes, and bread. Complex carbs typically include fibre and a range of micronutrients and take longer to digest because they are made up of longer strands of sugar molecules. Because of this, they typically release energy more slowly and prolong feelings of fullness.

The simple and complex classification for understanding the rate of carbohydrate metabolism works for the general public. As a nutrition coach however, it’s important to underline that not all complex carbohydrate sources are slow-releasing, and vice versa. Understanding the glycaemic index and glycaemic load of different foods is a much more accurate approach, and this is the sort of things students on our nutrition courses learn how to do.

Carbohydrates to fuel exercise

Endurance athletes who are engaged in activities with prolonged duration heavily rely on glycogen stores to meet energy demands. Depletion of these stores can lead to premature fatigue and a decline in performance. Carbohydrates play a crucial role in delaying glycogen depletion during endurance exercise, providing a sustained source of energy and extending time to physical exhaustion.

During an endurance event, the timing and composition of carbohydrate intake is paramount. Sports drinks, energy gels and other high-carbohydrate snacks provide a convenient and easily digestible source of energy. This helps athletes maintain optimal performance. Beyond preventing glycogen depletion, strategic carbohydrate intake during endurance exercise also supports hydration and electrolyte balance, contributing to overall performance and stamina.

A HFE personal trainer encourages a client through a ropes exercise.

In strength sports, where power and explosiveness are of utmost importance, the body requires immediate access to energy. Carbohydrates in the form of glucose offer a rapid and efficient solution to these demands. During sports where repeated bouts of sprints occur, the body relies on anaerobic metabolism which utilises glucose derived from carbohydrates for quick bursts of energy. This immediate availability is essential for achieving peak performance in short-duration, high-intensity activities.

In terms of carbohydrate timing, it is recommended that you consume a pre-exercise meal 1 to 4 hours before activity. Aim for 1-4g carbohydrates/kg body weight, depending on exercise intensity and duration. Consuming 30-60g carbohydrates/hour while exercising will help to maintain blood glucose levels, prevent exhaustion, and improve performance if you exercise for 90 minutes or more.

Carbohydrates for overall health

Brain health

Beyond their role in athletic performance, carbohydrates play a role in supporting overall health, particularly concerning brain function. The brain is highly dependent on a constant supply of glucose for energy, and maintaining stable blood glucose levels is essential for optimal cognitive performance.

Weight management

Carbohydrates are an extremely valuable component of a health approach to weight management. Choosing complex carbohydrates, such as grains, fruits and vegetables, provides essential nutrients along with dietary fibre. This fibre not only aids in digestion but also contributes to a feeling of fullness, potentially reducing overall calorie intake. Including carbohydrates in a well-balanced diet supports weight maintenance or weight loss goals while still ensuring the body receives the necessary nutrients for optimal function.

Long term benefits

Carbohydrates can also contribute to long-term health, playing a preventative role in chronic disease. Whole grains, rich in complex carbohydrates, are associated with a reduced risk of cardiovascular disease, type 2 diabetes, and cancers. Fibre from carbohydrates supports healthy cholesterol levels and gut health. Embracing a diet that includes a variety of carbohydrates from whole, unprocessed sources sets the foundation for sustained well-being.

How many carbs should I consume daily?

The more an individual exercises, the more carbohydrates they require.  A 70 kg person may need to eat anywhere from 210–500+g of carbs per day, depending on their training volume and intensity as well as their degree of physical activity. Intakes might vary from 3–7+g/kg/day. Burke et al. (2013) further breakdown this into more detailed recommendations:

  • very light training (low intensity) – 3-5g/kg body weight
  • mild intensity (1 hour or so/day) – 5-7g/kg body weight
  • moderate high-intensity training (1-3 hours/day) – 6-10g/kg body weight
  • very high-intensity training (>4 hours/day) – 8-12g/kg body weight

Picture of a food label and a tape measure

Carbohydrate loading

Carbohydrate loading is a tactic in which athletes increase their carbohydrate diet in the days preceding up to a competition to boost muscle glycogen stores. Performance can therefore improve by delaying the onset of fatigue in endurance sports.

When it comes to carbohydrate loading before competition, there are a range of guidelines and tactics. World Athletics recommend elite runners ingest 10-12g/kg bodyweight in the 36-48 hours before the race, which means a 65kg individual would consume 650-780g carbohydrates.

Other tactics could include gradually increasing carbohydrate consumption for 5-7 days before competition, followed by tapering and lowering training volume. Carbohydrate loading is simply one option in an athlete’s toolbox for improving performance. Consistently high carbohydrate intake is essential for athletes to fuel training sessions while also optimising recuperation, as appropriate glycogen availability can increase muscle regeneration. When combined with a correct training programme and diet, a loading technique like the one discussed above, can help maximise the fuel muscles need for sports performance.

The carbo-loaded crown

As we can now see, carbohydrates emerge not only as a fuel source but also as a key element in optimising health and longevity. Their pivotal role in energy metabolism, immediate energy demands in short-burst high-intensity sports, sustaining longer endurance efforts, and overall health makes them irreplaceable. Recognising the individual needs of different athletic pursuits allows athletes to tailor their carbohydrate intake for optimal results. Carbohydrates stand out as the king of nutrients, bridging the gap between performance and health and well-being.



Burke, L.M., Hawley, J.A., Wong, S.H. and Jeukendrup, A.E., 2013. Carbohydrates for training and competition. Food, Nutrition and Sports Performance III, pp.17-27.

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