What is another name for carbohydrate loading?

October 24, 2025 •

4 min read

Carbohydrates are the body's primary energy source during aerobic exercise. For endurance athletes, the process of maximizing stored energy is widely known as carbohydrate loading, but this dietary practice has another, more scientific name: glycogen supercompensation.

Quick Summary

This article discusses the scientific and common names for carbohydrate loading, explores its purpose, optimal timing and foods, and addresses key benefits and potential side effects for endurance athletes.

Key Points

Glycogen Supercompensation: This is the scientific name for carbohydrate loading, a dietary technique used by endurance athletes.
Maximizing Fuel Stores: The process aims to maximize the storage of glycogen, the body's primary energy source, in the muscles and liver.
Not a Single Meal: Effective carb loading is a multi-day process, typically starting 2-3 days before an event, not a single large meal the night before.
Endurance-Specific: This strategy is generally beneficial only for events lasting longer than 90 minutes, such as marathons or triathlons.
Potential Side Effects: Athletes may experience temporary weight gain from water retention and potential digestive issues.
Choose Simple Carbs: For loading, focus on easily digestible, low-fiber carbs like white rice, pasta, and potatoes to avoid stomach upset on race day.

The Science Behind Glycogen Supercompensation

While "carb loading" is the common term, the more scientifically accurate name for this dietary strategy is "glycogen supercompensation". This term perfectly describes the physiological goal: to maximize or "supercompensate" muscle and liver glycogen stores beyond their normal resting levels. Glycogen is the stored form of glucose that the body uses for fuel during high-intensity endurance exercise. By increasing carbohydrate intake in the days leading up to an endurance event, an athlete aims to overfill these glycogen reserves.

How Glycogen Supercompensation Works

Energy Reserves: Glycogen stores are the body's readily available fuel source, particularly crucial for activities lasting longer than 90 minutes.
Preventing 'Hitting the Wall': When glycogen stores are depleted, athletes can experience severe fatigue, often called "hitting the wall." Maxing out glycogen reserves delays this onset of fatigue.
The Original Method: Early protocols, developed in the 1960s, involved an initial depletion phase of intense exercise and low-carb eating. This was followed by a loading phase of rest and high-carb intake to trigger the supercompensation effect.
The Modified Method: Modern, less arduous protocols have shown that well-trained athletes can achieve maximal glycogen stores without the depleting phase. Resting or tapering combined with high-carb intake over several days is sufficient.

The Optimal Protocol for Carb Loading

The traditional image of an athlete eating a huge plate of pasta the night before a race is often misleading and ineffective. Proper carbohydrate loading is a multi-day process that requires planning. It involves adjusting macronutrient ratios and timing to optimize glycogen storage.

Practical Steps for Effective Fueling

Timing is Key: Begin the carb-loading process 2 to 3 days before an endurance event lasting over 90 minutes.
Increase Carbohydrate Intake: The daily intake should increase significantly, up to 70% to 90% of total calories, depending on the athlete's body weight. The aim is roughly 10-12 grams of carbs per kilogram of body weight per day.
Reduce Other Macros: To accommodate the increased carbohydrate calories without excessive weight gain, reduce fat and protein intake slightly.
Taper Training: Exercise should be reduced or tapered to minimize glycogen use, allowing the body to dedicate resources to storage.
Choose the Right Foods: Focus on complex carbohydrates like pasta, rice, potatoes, and bread, while opting for low-fiber versions a day or two before the event to minimize digestive distress. Liquid carbs like fruit juice and sports drinks can also be useful for some athletes.

Carb Loading vs. Standard Nutrition for Athletes


Feature	Standard Athlete Nutrition	Carb Loading Protocol
Carb % of Calories	~45-65%	Up to 70-90%
Duration	Ongoing for daily training and recovery	A specific 2-4 day period before a major event
Fiber Intake	High, from whole grains, fruits, vegetables	Lower, with a focus on simple, digestible carbs
Training Intensity	Varies based on training program	Decreased significantly (tapering)
Primary Goal	Sustain daily energy, support training adaptation, and recover	Maximize stored glycogen for peak performance on event day
Associated Weight Gain	Minimal to none, focused on stable weight	Temporary gain of 2-4 lbs due to stored water

Potential Side Effects and Considerations

While effective for many, carbohydrate loading is not without potential downsides. Athletes should test their strategies during training to avoid race-day complications.

Temporary Weight Gain: As glycogen is stored, it pulls water into the muscles. This can cause a temporary 2-4 pound weight gain, which can feel uncomfortable for some athletes.
Digestive Discomfort: A sudden increase in carbohydrate and, sometimes, fiber can cause bloating, gas, or other gastrointestinal issues. Choosing low-fiber, easily digestible carb sources can help mitigate this.
Blood Sugar Fluctuation: Individuals with conditions like diabetes must consult a physician before attempting this regimen, as it can significantly impact blood sugar levels.
Not for Everyone: Carb loading is not necessary for shorter events lasting less than 90 minutes. For these, a well-balanced, regular diet is sufficient.

Conclusion

Carbohydrate loading, or glycogen supercompensation, is a specialized nutritional tactic used by endurance athletes to maximize their stored energy for prolonged events. It involves a strategic increase in carbohydrate intake and a reduction in training volume in the days preceding a competition. While not a one-size-fits-all solution, when executed correctly by experienced athletes, this practice can effectively delay fatigue and improve performance over long distances. Understanding the science behind this practice allows athletes to move beyond the "pasta party" myth and implement a more deliberate, effective fueling strategy for race day. By tailoring the approach to individual needs and testing it beforehand, athletes can effectively leverage this nutritional technique to reach their performance goals. Learn more about the science of sports nutrition from the American College of Sports Medicine.

Frequently Asked Questions

The primary benefit of carbohydrate loading is increasing muscle and liver glycogen stores, which delays the onset of fatigue and improves endurance performance in events lasting longer than 90 minutes.

No, carbohydrate loading is not necessary for everyone. It is most beneficial for endurance athletes competing in events that exceed 90 minutes. For shorter activities, a normal balanced diet is sufficient.

Effective foods for carb loading include complex, low-fiber carbohydrates like pasta, rice, potatoes, bread, and oats. Some athletes also use sports drinks and fruit juices to increase carb intake.

A proper carbohydrate loading protocol typically takes place over 2 to 4 days, not just the night before a competition. It involves a gradual increase in carb intake combined with tapering exercise.

Yes, temporary weight gain is a common side effect of carb loading. For every gram of glycogen stored, the body also stores approximately three grams of water, leading to a temporary increase in body weight.

It is generally recommended to focus on lower-fiber carbohydrates in the 1-2 days immediately before a race to minimize the risk of digestive issues like bloating or diarrhea.

The classic method included an initial glycogen depletion phase with hard exercise and a low-carb diet, which modern research has shown is often unnecessary. The modern approach focuses simply on tapering exercise and increasing carbs for several days.