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While some athletes avoid carbohydrates during exercise out of fear of insulin resistance, others try to consume more than 120 grams per hour. Find out which approaches influence performance and what scientific research has to say.

Discussions about carbohydrate intake during sport are currently quite heated. As a result, some athletes avoid carbohydrates completely during intense exercise because they fear insulin resistance and weight gain, while others attempt to consume up to 120 grams per hour or even more in extreme cases. Both approaches can have significant consequences: in the first case, performance suffers during activities lasting longer than 60 minutes, and in the second case the risk of bloating and diarrhoea increases. There is no convincing scientific evidence showing that a consistently high intake of carbohydrates or sugar during training or competition is inherently harmful to health, provided the intake matches the body’s energy requirements.

The aim should therefore be to consume carbohydrates wisely and consciously in order to benefit from their advantages while avoiding the drawbacks. In principle, it is important to distinguish between sugar intake during sport and general sugar consumption in everyday life. While the former can be considered beneficial, there are several points to keep in mind when it comes to overall sugar intake:

• The World Health Organization (WHO) recommends that no more than ten per cent of daily calorie intake should come from sugar
• Sugar only becomes problematic when it is consumed in excessive amounts overall
• Naturally occurring sugars, such as those found in fruit, are not an issue
• If you feel like having something sweet, enjoy it in moderation Strict bans and overly rigid dietary rules increase the release of the stress hormone cortisol, which can lead to various negative long-term health effects
• Avoid highly processed foods, as they usually contain not only sugar but also other ingredients that may be harmful to health

Sugar can improve performance

Studies show that a marathon is completed on average four minutes faster when runners consume sugary sports drinks during the race rather than only water. The reason is that sugar can help delay fatigue by providing quickly available energy for both muscles and the nervous system. This intake is not only useful for the marathon distance, but already beneficial from about one hour of race duration, as sugar supports both the muscles and nervous system.

For optimal performance, 60 to 90 grams of sugar per hour are recommended. For longer distances, even higher amounts may be possible due to the lower intensity. To ensure proper absorption, a combination of glucose or maltodextrin and fructose is necessary. To avoid digestive issues during competition, this intake should always be practised in training beforehand.

Sugar during exercise influences how much you eat afterwards

Further studies show that consuming carbohydrates during exercise leads to a lower calorie intake afterwards. The fear that sugary sports drinks and gels lead to weight gain is therefore unfounded. Instead, they should be used strategically at the end of particularly long or intense sessions to initiate recovery and help prevent strong hunger cravings.

However, not every training session requires a high carbohydrate intake. Targeted training sessions with little or no carbohydrates can also be beneficial and help improve metabolic flexibility – the body’s ability to switch quickly and efficiently between fat and carbohydrate metabolism.