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Fuelling for a race can feel overwhelming at times with nutrition having the power to make or break your event. Here at Science in Sport, you’ve probably noticed grams of carbohydrate is displayed quite clearly on most of our products, but why is this?

Knowing how much carbohydrate is in a product can be key to your nutrition strategy and we want you to be able to be in control of your nutrition and know exactly what you’re taking in.

Naturally, if following a healthy balanced diet our bodies can store enough fuel to last ~ 90 minutes of exercise, anything longer than this and fuelling becomes vital to sustain our energy levels. There are many factors that will affect how much fuel we need but two important factors are exercise duration and intensity.


Exercise duration and intensity

Planning on how long you will need to fuel for is vital to getting your nutrition right. It’s better to overestimate and carry more than underestimate and “bonk” during your event.

The chart below is designed to help you decide how many grams of carbohydrate per hour you should aim for depending on the exercise duration and intensity.

Carbohydrate recommendation in g per hour
Hard 0 30-60 30-60 60-90 80-120 80-120
Moderate 0 0 30-60 30-60 60-90 80-120
Easy 0 0 0 30-60 30-60 60-90
30 min 60 min 90 min 2 hr 2.5 hr 3 hr +

What’s easy? – You’ll be able to breathe normally throughout

What’s moderate? – Your breathing is more laboured, but you’re still fairly comfortable

What’s hard? – You’ll be breathing heavily and it will feel pretty uncomfortable

Some of these amounts may seem like a lot of carbohydrate and we recommend building up your tolerance in training gradually so your body can become accustomed to this amount. Lighter athletes should aim for the lower end of the recommendations.

How many g of carbohydrates in SIS products?

The amount of carbohydrate in SIS products varies but here is a useful summary below of some of our more popular products!

Product g of carbohydrate per serving
GO Isotonic energy gels 22g
Beta Fuel energy gels 40g
GO Energy powder 47g
GO Electrolyte powder 36g
Beta Fuel powder 80g
GO energy mini bar 26g
Beta Fuel energy chews 40g

But how do you pick which product to go for? A lot of this will come down to personal preference on taste and texture (i.e. gels vs more solid-food is a big individual preference), however you should also take into account the type of carbohydrate.

If wanting to consume more than 60 g of carbohydrate per hour, you should try and use fuel sources that have multiple types of carbohydrate to optimise carbohydrate absorption. This is because different types of carbohydrates have different transporters to carry glucose from the gut to the blood, with the maximum rate of a single carbohydrate source such as maltodextrin being around 60 g per hour.

Fructose has a different transporter than glucose, a dual source formulation allows for greater carbohydrate delivery to our muscles during exercise, therefore increasing how much carbohydrate we can use. Our Beta Fuel range in particular works by providing these two different forms of carbohydrate which can be simultaneously absorbed so is ideal if you’re aiming for more than 60 g per hour.

You can read more about how to fuel with our Beta Fuel range here but for an example of trying to consume 80 – 120 g of carbohydrate for a 4 hour event using Beta Fuel see the diagram below!

Take home messages

  1. Exercise intensity and duration should influence how you choose your nutrition.
  2. It may take time for your body to adjust to high amounts of carbohydrate, this should be done gradually during training, never try anything new on race day!
  3. If wanting to consume over 60 g of carbohydrates per hour, try to use fuel sources with multiple types of carbohydrate.


Written By

Dr Emily Jevons - PhD in Exercise Physiology & Nutrition, Clean Sport Advisor

Emily has worked with Science in Sport since 2021. With a PhD in Exercise Physiology & Nutrition, she currently provides nutritional advice for endurance athletes. Emily not only understands the science behind performance nutrition solutions, but also the physiological and psychological demands of sport after competing competitively in swimming and triathlon for a number of years.