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Carbohydrates for metabolic performance.

Carbohydrates are the body’s primary energy source for cellular and metabolic function. Different carbohydrates function in different ways, from providing slow-releasing energy to aiding digestion. Understanding carbohydrates and how to use them can make a massive difference when it comes to fuelling your success.

What are carbohydrates?

Carbohydrates consist of sugar molecules found as both simple structures or longer, more complex chains [2]. They are the body’s most efficient energy source for metabolism and cellular processes. There are three types of carbohydrates; sugars, starches, and fibre.

The role of carbohydrates in the body

  • Rapid energy source.Our cells use simple carbohydrates (sugars) such as glucose to produce energy for cellular function. These molecules are broken down during a process called respiration, which produces ATP, a chemical energy molecule used by the cells [2].

  • Slow-releasing energy.Some carbohydrates, called starches, are complex forms made from chains of simple sugars. They serve the same purpose as sugars; however, they must first be processed and broken down by the body [3]. This means they take longer to digest and are therefore considered a source of slow-releasing energy.

  • Energy storage.When carbohydrates are broken down for energy production, any excess sugar is converted into a compound called glycogen [2]. Glycogen acts as a readily-available energy source and is stored in the muscle and liver. It can be broken down quickly when the cells need it, providing a reliable energy source for a short period of time. Once glycogen stores are full, excess glucose will be converted and stored as fat [4].

  • Aiding digestion.Some types of complex carbohydrates cannot digest be digested by the body. These are called fibre, and there are two main types; soluble fibre and insoluble fibre.Soluble fibre can dissolve in water and acts as a food source for our healthy gut bacteria. It also provides them with the raw ingredients they need to create important metabolites for the body [5]. Additionally, soluble fibre can help slow the rate of digestion for other nutrients such as fats and sugars. Insoluble fibre cannot dissolve in water and consequentially cannot be digested. Therefore, it makes its way to the intestinal tract, where it aids with digestion [6].

Glycemic index and Glycemic load

As you digest carbohydrates, the resulting sugars will enter the bloodstream for transport across the body. As your blood sugar levels rise, the pancreas releases insulin, a hormone that signals the cells to absorb this sugar for energy production or storage [1].


When you consume simple carbohydrates, blood sugar levels will rise rapidly as they are easily digested and absorbed by the body [1]. Insulin levels rise to accommodate this change, and the cells are signalled to absorb a large amount of sugar. Once energy demands are met, and glycogen stores are full, the excess sugar is stored as fat [4].


On the other hand, complex carbohydrates take longer to digest, so sugars are released slowly into the bloodstream. The gradual supply of sugar will cause less insulin to be released, and cells will absorb the sugar slower [1]. Our cells will gradually use the sugar as normal metabolic functions demand it, and less excess will be available to convert and store as fat.


The interaction between the digestion of carbohydrates and blood sugar levels is described by the term glycemic index (GI). Effectively it provides a rating for carbohydrates (from 0-100) based on the rate at which they will raise sugar levels in the blood [7]. The lower the GI score, the slower it will raise your blood sugar levels. Low GI is below 55, medium GI is 56-69, and high GI is greater than 70.


It is worth noting that the glycemic index only reflects the rate at which carbohydrates raise blood sugar levels, not the amount. The quantity of carbohydrates in food is also an important factor that determines how high your blood sugar levels may rise after a meal [8]. Glycemic load (GL) is a term that accounts for both of these elements. It effectively takes the GI score and multiplies it by the amount of carbohydrates in a given food [9]. Similarly to GI, there are three categories for glycemic load; low being ten or less, medium being 11-19, and high being 20 or more.

Practical applications

Many people are led to believe that carbohydrates are the enemy. In reality, getting the right types of carbohydrates in the right quantities can be the difference between failure and success when it comes to your health and performance goals.


As carbohydrates are the primary energy source for our cells, it is essential to consume enough of them to provide fuel for activity. This becomes particularly important when optimising intensive training and sports, as the muscles will use carbohydrates and glycogen stores to contract effectively and repeatedly [2]. Carbohydrates also play an essential part in recovering from training, as the glycogen stores you deplete during intensive exercise should be replaced to avoid fatigue [10].


It is also worth noting that the type of carbohydrates you consume can immediately impact performance. Complex carbohydrates are more likely to provide sustained energy throughout an activity, whilst simple carbohydrates can be effective for rapid energy production [1]. However, too many simple carbs can lead to excess and unwanted storage as body fat [4].


Additionally, it is essential to provide your body with an adequate fibre intake, as this will aid the digestion and absorption of other nutrients. It will also provide food for the bacteria in your gut, allowing them to thrive and work for you in several beneficial ways [5].


For these reasons, it is crucial that you balance both the quantity of carbohydrates you consume as well as the type, ideally sourcing them from quality, natural ingredients.

The radix solution

At Radix, we strive to create the best quality products for the best possible performance. With a focus on nutrient density, the Radix Nutrition Architecture (RNA) includes the recommended daily intake of carbohydrates and fibre whilst also considering factors such as glycemic load and glycemic index. Using these as a framework, our products are designed to provide adequate carbohydrates to fuel your success, sourced from quality ingredients such as vegetables, seeds and grains.

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    4. Healthline. What are the key functions of carbohydrates? 2017 [cited 2022 28/01]; Available from:
    5. Healthline. Why Is Fiber Good for You? The Crunchy Truth. 2021 [cited 2022 28/01]; Available from:
    6. Healthline. Good Fiber, Bad Fiber - How The Different Types Affect You. 2017 [cited 2022 28/01]; Available from:
    7. Trumbo, P.R., Global evaluation of the use of glycaemic impact measurements to food or nutrient intake. Public Health Nutr, 2021. 24(12): p. 3966-3975.
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    9. Healthline. Glycemic Index: What It Is and How to Use It. 2020 [cited 2022 28/01]; Available from:
    10. Williams, C., Macronutrients and performance. J Sports Sci, 1995. 13 Spec No: p. S1-10.