Carbohydrates are more than just "fast energy". The body can store them as glycogen – a branched glucose molecule that is readily available in the liver and muscles. For active people, this store is crucial: at higher exercise intensities, muscle glycogen becomes one of the most important energy sources. When stores are significantly depleted, performance, work capacity and often training quality decline.
How large are our glycogen stores?
An average adult stores roughly 500 g of glycogen in the muscles and about 100 g in the liver. That corresponds to approximately 2,400 kcal of carbohydrate energy. The individual range, however, is wide: muscle mass, training status, diet and previous exercise determine how full the store is at any given time. Trained, muscular people can store considerably more, particularly in the muscles.
The two stores have different roles:
💪 Muscle glycogen
Fuels the muscle itself. It cannot be released into the blood as glucose.
🫀 Liver glycogen
Stabilises blood sugar between meals and overnight. Among other things, it supplies the brain and red blood cells.
Glycogen also binds water: when stores are replenished, body weight often rises by one to several kilograms in the short term. This is not fat gain – it is mainly stored glucose plus water.
How quickly do stores refill after exercise?
After an intense or long training session, the muscles are particularly receptive: they transport glucose into the cell more easily, and the enzyme glycogen synthase becomes more active. This works even if you rest after training – muscle contraction is no longer required. ,
How quickly the store fills up again depends on four factors:
●
How much the muscle was actually depleted
●
How much carbohydrate is consumed
●
How quickly it becomes available
●
How much time remains before the next session
When rapid recovery is needed – for example with two hard sessions on the same or the following day – around 1.0–1.2 g of carbohydrate per kg of body weight per hour during the first four to six hours is considered an effective range. If less carbohydrate is tolerated or desired, protein can support glycogen replenishment somewhat; when carbohydrate intake is already sufficiently high, additional protein provides no further acceleration for the glycogen store itself.
Important: "refilling quickly" does not mean "full again within a few hours". A recent study in well-trained cyclists illustrates this clearly: after heavy depletion, participants consumed a total of 10 g of carbohydrate/kg body weight within twelve hours – as much as 1.2 g/kg/h during the first six hours. Even so, after twelve hours the muscle had only reached about 69% of its starting level. Liver glycogen, by contrast, was already fully restored after six hours.
The practical message: the muscle is slow, the liver is fast. After a truly depleting session, a period of around 24 hours is usually more realistic for fully restored muscle glycogen.
What happens at rest and overnight?
At rest, the muscle glycogen store continues to refill as long as glucose is available from the gut and the blood. So a night's sleep is no break from recovery. After a carbohydrate-rich dinner, replenishment continues during the first few hours.
Later in the night, when no more food is coming in, the situation changes: the liver releases glucose from its store again to stabilise blood sugar. Muscle glycogen, on the other hand, largely stays in the muscle. Anyone who keeps their carbohydrate intake far too low in the evening after a very hard session therefore often starts the next morning with incomplete muscle recovery and liver glycogen that has dropped again.
For a session the following day, it is not only the meal immediately after training that matters. What counts is the total amount of carbohydrate over the following 24 hours.
Is excess glucose immediately turned into fat?
No. High blood sugar after a meal does not mean that excess glucose is immediately converted into body fat. The body has several intermediate stages:
●
It uses glucose directly for energy.
●
It first refills liver and muscle glycogen.
●
At the same time, it reduces fat burning.
●
Only with a prolonged, significant energy surplus and largely full stores does the formation of new fat from carbohydrates (de novo lipogenesis) increase to a relevant degree. ,
The important nuance: in a calorie surplus, body fat often increases not primarily because glucose is turned directly into fat. More commonly, dietary fat is stored more easily because the body burns less fat when glucose is plentiful. In the long run, energy balance is what counts – not a single carbohydrate-rich meal.
The conversion of glucose into fat (de novo lipogenesis) increases mainly with a sustained, significant surplus of energy and carbohydrate – particularly when glycogen stores are already well filled. It is not the immediate, standard consequence of a single carbohydrate-rich meal or of 70 g of carbohydrate per hour after a hard training session.
Exercise has a clear advantage here: depleted muscle glycogen stores are a large, metabolically healthy "buffer" for carbohydrates. In a metabolic study of healthy people under the influence of insulin, 70–90% of the glucose consumed was stored as muscle glycogen.
Practical tip: a croissant or custard pastry, for example, does provide carbohydrates, but also a relatively large amount of fat. When the carbohydrates raise insulin, fat burning is temporarily slowed – and the fat eaten alongside can be stored more easily. To specifically refill empty glycogen stores, lower-fat carbohydrate sources such as potatoes, rice, bread, oats or pasta are therefore usually the better choice.
How quickly can glycogen stores be refilled?
⏱️ 0–4 hours after heavily glycogen-depleting training
Recommended carbohydrate intake: 1.0–1.2 g/kg body weight/hour
What is actually stored: muscle glycogen in studies approx. 3–4 g/kg dry muscle/hour
Context: This is the phase of fastest replenishment: trained muscle is particularly sensitive to insulin and glucose. An intake of 1.0–1.2 g/kg/h maximises replenishment, but is not stored entirely as glycogen.
🍽️ Afterwards, or without prior hard training
Recommended carbohydrate intake: for a steady supply, approx. 0.3–0.5 g/kg body weight/hour, spread across meals
What is actually stored: considerably slower, and dependent on starting level, activity and total energy requirements
Context: In everyday life there is no "turbo refill phase". Carbohydrates are needed at the same time for the brain, movement, resting metabolism and liver glycogen. A steady intake therefore makes more sense than large single portions.
🌙 Over 24 hours after heavy depletion
Recommended carbohydrate intake: usually 7–10 g/kg/day in total if very intense training follows the next day
What is actually stored: substantial, but not necessarily complete, replenishment within 24 hours
Context: For normal recreational training, this high amount is usually not necessary.
Example for 70 kg: after a very hard session, 70–84 g of carbohydrate per hour during the first four hours would be the study strategy for maximum speed. In normal everyday life, 0.5 g/kg/h corresponds to about 35 g per hour – in practice, for example, 60–80 g per main meal plus smaller carbohydrate-containing snacks.
Important: 1.0–1.2 g/kg/h describes the recommended intake, not the net storage rate. Part of the glucose is oxidised immediately, refills the liver or covers ongoing energy needs. ,
Glycaemic index: a useful tool, not a health verdict
A high glycaemic index initially means only one thing: a carbohydrate-containing food raises blood sugar comparatively quickly. That does not automatically make it healthy or unhealthy.
A permanently high-glycaemic eating pattern can be problematic – particularly when it consists of highly processed, energy- and fat-rich foods combined with little physical activity. Repeated high blood sugar and insulin spikes during an energy surplus can promote insulin resistance, fat accumulation in the liver and, in the long term, unfavourable body fat gain. The GI alone, however, does not explain these risks: quantity, frequency, energy surplus, food quality and physical activity are what matter.
After heavily glycogen-depleting exercise, the situation is different. The working muscles are then particularly insulin-sensitive and can preferentially take up glucose as glycogen. In this short window, rapidly available carbohydrates can speed up replenishment. In a study of trained cyclists with the same high carbohydrate intake over 24 hours, muscle glycogen replenishment was greater with high-glycaemic foods than with low-glycaemic foods.
For normal everyday life, the practical consequence is: low- to moderate-glycaemic, minimally processed carbohydrate sources form the foundation. Rapidly available carbohydrates are a targeted tool after very intense exercise or when recovery time is short – not the basis of every meal.
⚡ High GI – rapidly available
●
Glucose, maltodextrin
●
White bread, toast, baguette
●
Rice cakes, cornflakes
●
Mashed potatoes, baked potatoes
●
White rice, especially quick-cooking
🌾 Low GI – more slowly available
●
Pulses: lentils, beans, chickpeas
●
Oats, pumpernickel, wholegrain bread
●
Pasta al dente
●
Brown rice, quinoa
●
Dairy products such as natural yoghurt
The GI is not a fixed value: variety, ripeness, preparation and combination with protein, fat and fibre change the blood sugar response considerably.
Refilling glycogen stores sensibly over 24 hours
If you want to refill your stores without unnecessarily overloading on energy, you can follow five simple principles:
●
Match your carbohydrate intake to your actual training volume. After a light strength or everyday session, no aggressive refilling strategy is needed. After long, intense or twice-daily sessions, it is.
●
Start early when time is tight. If performance is required again within eight to twelve hours, the first few hours after training are particularly valuable. More frequent portions then make more sense than one very large serving.
●
Plan the total amount across the day. For complete replenishment after heavy endurance exercise, around 8–10 g of carbohydrate/kg body weight within 24 hours may be necessary. With a normal training volume, requirements are usually considerably lower.
●
Don't go unnecessarily "low carb" in the evening. After a late, depleting session, a carbohydrate-rich evening meal can support replenishment during the first hours of the night.
●
Don't consume more than training and daily energy requirements justify. Full stores make sense. A permanent calorie surplus with already full stores does not.
Take-home message
Glycogen is not the enemy of fat loss – it is the body's high-performance carbohydrate store. After exercise, the muscle takes up glucose particularly well. By adapting your carbohydrate intake to your training load, recovery time and total energy requirements, you can refill your stores very effectively within about 24 hours – without a single larger portion of carbohydrates automatically turning into body fat.
Quellen
1: Jensen J, Rustad PI, Kolnes AJ, Lai YC. The role of skeletal muscle glycogen breakdown for regulation of insulin sensitivity by exercise. Front Physiol. 2011 Dec 30;2:112. doi: 10.3389/fphys.2011.00112. PMID: 22232606; PMCID: PMC3248697.
2: Burke LM, van Loon LJC, Hawley JA. Postexercise muscle glycogen resynthesis in humans. J Appl Physiol (1985). 2017 May 1;122(5):1055-1067. doi: 10.1152/japplphysiol.00860.2016. Epub 2016 Oct 27. PMID: 27789774.
3: Beelen M, Burke LM, Gibala MJ, van Loon LJC. Nutritional strategies to promote postexercise recovery. Int J Sport Nutr Exerc Metab. 2010 Dec;20(6):515-32. doi: 10.1123/ijsnem.20.6.515. PMID: 21116024.
4: Fuchs CJ, Veeraiah P, Hermans WJH, Brauwers B, Voncken R, Brouwers K, Petrick HL, Hendriks FK, Bels JLM, van den Hurk J, Weber J, Senden JM, Smith FE, Thelwall PE, Prompers JJ, van Loon LJC. Carbohydrate intake of 10 g/kg body mass rapidly replenishes liver, but not muscle glycogen contents, during 12 h of post-exercise recovery in well-trained cyclists. J Physiol. 2025 Aug 20. doi: 10.1113/JP289115. Epub ahead of print. PMID: 40836481.
5: Acheson KJ, Schutz Y, Bessard T, Anantharaman K, Flatt JP, Jéquier E. Glycogen storage capacity and de novo lipogenesis during massive carbohydrate overfeeding in man. Am J Clin Nutr. 1988 Aug;48(2):240-7. doi: 10.1093/ajcn/48.2.240. PMID: 3165600.
6: Burke LM, Collier GR, Hargreaves M. Muscle glycogen storage after prolonged exercise: effect of the glycemic index of carbohydrate feedings. J Appl Physiol (1985). 1993 Aug;75(2):1019-23. doi: 10.1152/jappl.1993.75.2.1019. PMID: 8226443.
