How many calories to replenish glycogen? Your guide to post-workout refueling

October 20, 2025 •

4 min read

After intense and prolonged exercise, muscle glycogen stores can be substantially depleted, with studies showing a near 90% reduction in some cases. To understand how many calories to replenish glycogen, one must first recognize that the refueling process is primarily driven by carbohydrate intake, which directly influences recovery and future performance.

Quick Summary

This article explores the caloric needs for glycogen replenishment, detailing how carbohydrate intake, timing, and exercise intensity influence recovery. It breaks down the numbers required for different training levels and outlines a strategic approach to optimize post-workout nutrition.

Key Points

Carbohydrate Focus: The number of calories for glycogen replenishment is directly tied to carbohydrate intake, with each gram providing 4 calories.
Immediate Replenishment Window: Consuming 1.0–1.2 g/kg of carbs per hour within 30 minutes to 2 hours post-exercise maximizes rapid glycogen synthesis.
Daily Intake for Full Repletion: Total daily carbohydrate needs vary based on training load, ranging from 5–7 g/kg for moderate training to 8–12 g/kg for very heavy training.
High-Glycemic Carbs are Key Post-Workout: In the immediate recovery phase, high-GI carbs like sports drinks or white rice are more effective due to quicker absorption.
Adding Protein for Efficiency: Combining protein with carbohydrates can boost glycogen synthesis, especially when carbohydrate intake is suboptimal.
Adequate Total Calorie Intake is Essential: Overall energy balance is critical, as sufficient total caloric intake is needed for complete glycogen replenishment, regardless of carb intake.
Timing Matters for Recovery: Proper nutrient timing can accelerate recovery and impact subsequent exercise performance, especially in scenarios with short recovery periods.

The crucial role of glycogen for performance

Glycogen is the stored form of glucose, primarily located in the muscles and liver, and it serves as the body's main fuel source during high-intensity exercise. For athletes and active individuals, having well-stocked glycogen reserves is critical for sustaining performance. The body's total glycogen capacity typically holds around 2,000 to 2,200 calories, with roughly 1,400 to 1,800 calories stored in the muscles and 320 to 400 calories in the liver. This supply is finite and can be depleted rapidly during intense or prolonged activity, leading to fatigue, often referred to as "hitting the wall".

Replenishing these stores efficiently is the cornerstone of effective recovery and preparation for subsequent training sessions or competitions. The number of calories needed to replenish glycogen is directly tied to the quantity of carbohydrates consumed, as each gram of carbohydrate contains approximately 4 calories. However, simply consuming carbs isn't enough; the timing, type, and amount all play significant roles in the rate and extent of glycogen resynthesis.

Immediate post-exercise replenishment

Immediately following exercise, your muscles are most receptive to absorbing glucose from the bloodstream, a period often called the "anabolic window". During this time, glycogen synthase activity is high and the muscle's sensitivity to insulin is increased, allowing for rapid glycogen resynthesis. The following guidelines focus on maximizing replenishment during this initial window:

Timing: Consume carbohydrates as soon as possible after exercise, ideally within the first 30 minutes to 2 hours. Delayed intake can slow the rate of glycogen synthesis by up to 50%.
Amount: Experts recommend consuming 1.0 to 1.2 grams of carbohydrate per kilogram of body weight per hour (g/kg/h) during the first four hours post-exercise. For a 70 kg (154 lb) athlete, this translates to 70–84 grams of carbohydrates per hour. This frequent, high-volume intake is most important for those with very limited recovery time between sessions.
Type: High-glycemic index (GI) carbohydrates are most effective in this phase because they are quickly digested and absorbed, causing a rapid insulin spike that aids in glucose uptake. Glucose or maltodextrin-based sports drinks and gels are excellent options. Combining glucose and fructose may also accelerate liver glycogen replenishment.
Protein Co-ingestion: For athletes with lower carbohydrate intake (below 0.8 g/kg/h), adding protein (0.2–0.4 g/kg) can enhance glycogen resynthesis. The synergistic effect of carbohydrates and protein on insulin secretion aids in driving glucose into muscle cells.

Longer-term daily intake for full repletion

Beyond the initial recovery window, total daily carbohydrate intake determines full glycogen repletion, which can take 24–48 hours depending on the extent of depletion. For athletes with longer recovery periods, the focus shifts to overall daily macros rather than the urgency of the immediate post-workout meal.

Moderate training (1 hour+): Aim for 5–7 g/kg of carbohydrates per day.
Heavy training (1–3 hours+): Target 6–10 g/kg of carbohydrates per day.
Very heavy or ultra-endurance training: Needs can increase to 8–12 g/kg of carbohydrates per day.

Comparison of recovery meal strategies

The table below outlines different recovery approaches based on the intensity and timing of training, providing a practical guide for athletes and active individuals.


Strategy	Best for	Carbohydrate Timing	Carb Amount	Nutrient Notes	Typical Outcome
Rapid Refueling	High-intensity, multi-session days	Immediate post-exercise and every 2 hours	1.0–1.2 g/kg/h for 4 hours	Consider high-GI carbs; protein can be added for lower carb doses	Rapid glycogen restoration, supports quick turnaround
Standard Recovery	Moderate-intensity, single daily sessions	Normal meals and snacks throughout the day	5–7 g/kg daily	Focus on quality whole-food carbohydrates	Complete glycogen restoration within 24 hours
Glycogen Loading	Pre-competition, exhaustive activity	Tapered exercise with increased carbs for 24-48 hours prior	8–12 g/kg daily	Maximize carbohydrate intake, potentially using sports nutrition products	Supercompensation, elevated glycogen stores for event
Train-Low	Experienced athletes seeking adaptation	Strategically restricting carbs to promote adaptations	Varies; often after an overnight fast or restricted overnight	Requires careful planning; not for max performance immediately following	Enhanced metabolic efficiency over time

Calculating your glycogen replenishment calories

To translate these carbohydrate recommendations into calories, use the standard conversion: 1 gram of carbohydrate = 4 calories.

Example calculation (70kg athlete):

For rapid refueling (first hour): 70 kg 1.2 g/kg/h = 84 g carbs. 84 g 4 kcal/g = 336 calories from carbs in the first hour.
For moderate training day (total): 70 kg 6 g/kg/day = 420 g carbs. 420 g 4 kcal/g = 1680 calories from carbs for the day.

It's important to remember that these are not additional calories, but rather the portion of your total daily energy intake that should be allocated to carbohydrates to facilitate optimal glycogen storage. Total energy intake must also be sufficient to meet overall demands; otherwise, even with adequate carb intake, glycogen repletion will be impaired.

Nutrient timing and food choices

While the science points to specific numbers, applying this in practice involves strategic food choices. For the immediate post-exercise window, easily digestible carbohydrates are key. For the broader 24-hour replenishment period, prioritizing high-quality, whole-food sources is beneficial for overall health.

High-Glycemic Carbohydrate Sources (for rapid recovery):

Sports drinks, gels, or chews
White bread or rice
Bananas
Potatoes (cooked)
Sweet potatoes (cooked)
Oatmeal with honey

Whole-Food Carbohydrate Sources (for sustained replenishment):

Whole grains (brown rice, quinoa)
Legumes and beans
Fruits and vegetables
Dairy products (yogurt, milk)

Conclusion

Replenishing glycogen stores is an essential, multi-faceted process crucial for athletic performance and recovery. The number of calories required, and more specifically the amount of carbohydrates, depends on the intensity of the exercise and the timeframe for recovery. For rapid replenishment, a higher, more frequent intake of simple carbohydrates is necessary in the initial hours post-exercise. For standard recovery, a sufficient total daily carbohydrate intake from a variety of quality sources is key. By strategically managing carbohydrate consumption, athletes can ensure their bodies are properly fueled and ready for the next challenge, avoiding the fatigue and impaired performance that comes with depleted glycogen levels.

Nutrition and athletic performance - Med Sci Sports Exerc, 48(3), 543-568.

Frequently Asked Questions

Glycogen is the body's stored form of carbohydrates, found mainly in the muscles and liver. It serves as the primary fuel source for high-intensity exercise, with adequate stores being critical for sustaining athletic performance and preventing fatigue.

To maximize the rate of glycogen replenishment, it is most effective to consume carbohydrates as soon as possible after exercise, ideally within the first 30 minutes to 2 hours. This period offers the highest rate of absorption.

For immediate recovery (within 2 hours), high-glycemic index (GI) carbohydrates like sports drinks, bananas, and white rice are most effective for rapid absorption. For longer-term replenishment, include a mix of whole grains, fruits, and vegetables.

Yes, adding protein can be beneficial. While carbs are the main driver, combining protein with carbs can enhance glycogen synthesis, especially if your carbohydrate intake is on the lower side. A 3:1 or 4:1 carb-to-protein ratio is often recommended.

While both types of athletes rely on glycogen, endurance athletes performing prolonged, intense exercise require a higher total daily carbohydrate intake to fully replenish stores. For strength athletes, while still important, the primary focus might also include muscle protein synthesis.

Low-carb diets are generally not sufficient to fully restore muscle and liver glycogen. In a state of ketosis, the body shifts to using ketones for fuel, and glycogen stores remain low. This can impact high-intensity exercise performance, which relies heavily on glycogen.

The time required for full replenishment depends on the level of depletion and carbohydrate intake. It can take between 24 and 48 hours to fully restore glycogen stores, assuming a high-carbohydrate diet and adequate rest.

Multiply your body weight in kilograms by the recommended carbohydrate intake. For rapid post-exercise recovery, aim for 1.0–1.2 g/kg/h. For daily intake based on moderate training, use 5–7 g/kg/day.