Carbohydrates in Sport: Function, Requirement and Supplements

In short, very intense efforts, the body's own immediate energy stores supply the power, but in longer-lasting or repeatedly intense efforts the carbohydrate stores in muscles and liver become increasingly important. When these glycogen stores are well filled, a workout can generally be sustained at a high level for longer before fatigue sets in.

After training, carbohydrates together with protein help to refill the emptied glycogen stores and support recovery. Especially after extensive endurance sessions or several intense training days in a row, an adequate carbohydrate intake therefore makes sense, so that the body can start the next day with full stores again.

If glycogen stores are chronically poorly filled, on the other hand, for example on a very low-carbohydrate diet combined with a high training volume, this can show in training quality and recovery. That does not mean a reduced-carbohydrate diet is unsuitable in principle, but with intense training it should be planned deliberately so that enough energy is available for the most important sessions.

The actual requirement depends heavily on training volume, sport and individual goals, so only rough reference values can be given. People with little exercise often manage with a lower share of carbohydrates in total energy, whereas endurance athletes with a high training volume may need considerably more. The following table shows typical orders of magnitude as a first guide; it is best to discuss concrete values for your situation with a nutrition professional.

These values are deliberately given as ranges, because individual factors such as metabolism, the goal of the dietary change and tolerance of individual carbohydrate sources play a large role. When weight loss is the aim, the carbohydrate share is often reduced somewhat, but giving them up entirely is neither necessary nor sensible for most athletes.

A very low-carbohydrate diet can at first show in some people as weak performance, concentration problems or unusual tiredness, until metabolism has adjusted somewhat. If there are persistent, marked complaints, it makes sense to consult a doctor, especially if conditions such as diabetes are also present.

A lasting surplus of carbohydrates, especially in the form of foods and drinks high in sugar, by contrast favours a positive calorie balance and thus weight gain if the energy taken in is not used up overall. What matters is therefore less the individual nutrient group than the overall picture of amount, food quality and everyday activity.

That sufficiently filled glycogen stores support performance in long and intense efforts is one of the best-established basic principles of sports nutrition. The positive effect of a combined carbohydrate and protein intake on recovery after training is also well studied.

The evidence is less clear for individual add-on products such as carb blockers or special timing strategies, where the benefit compared with an overall balanced diet is often overestimated. For most recreational athletes, a needs-based basic diet with mainly complex carbohydrates matters more than reaching for individual specialty products.

The widespread worry that carbohydrates in the evening make you fat in general is also not confirmed by research. For weight development, the calorie balance over the whole day counts first and foremost, and the distribution of carbohydrates across individual meals plays a minor role. More important than a strict time of day is that the total amount suits training volume and goals.

Are carbohydrates generally bad when losing weight?

No. For weight loss, the calorie balance counts first and foremost. Carbohydrates can be reduced, but cutting them out completely is not strictly necessary and is hard for many people to sustain in the long run.

Do I need special carbohydrate supplements as a recreational athlete?

In most cases, no. A balanced diet with wholegrain products, fruit and vegetables normally covers the requirement well at a moderate training volume.

When are fast carbohydrates such as maltodextrin worthwhile?

Mainly in long or very intense training sessions, when quickly available energy is needed and there is not enough time for a full meal beforehand.

How do I recognise a carbohydrate deficiency?

Possible signs are weak performance, concentration problems and unusual tiredness in training. If complaints persist, it is advisable to have them checked by a doctor.

Do carbohydrates in the evening make you particularly fat?

No, what matters is the total amount of calories over the day. A fixed time of day after which carbohydrates should generally be avoided has no scientific basis.

Are wholegrain products always the better choice?

For the daily diet, wholegrain products are usually the more sensible choice because of their higher nutrient density. Around intense training, more easily digestible, faster carbohydrate sources can briefly have their place too.