Does Glycogen Bond with Water in the Body?

December 3, 2025 •

4 min read

For every gram of glycogen stored in the human body, approximately 3 to 4 grams of water are also retained. This is not a simple mixing process but a molecular association where glycogen's structure influences significant water retention within muscle and liver cells. Understanding how and why glycogen bonds with water is key to comprehending short-term body weight fluctuations, especially for athletes and those on low-carbohydrate diets.

Quick Summary

Glycogen's branched structure, loaded with hydroxyl groups, attracts and holds water molecules via hydrogen bonding within cells. This binding is central to carbohydrate loading and the rapid weight changes experienced when dietary carb intake increases or decreases. The water is released as glycogen is broken down for energy.

Key Points

Hydrogen Bonding: Glycogen bonds with water via hydrogen bonds, where the polar hydroxyl (-OH) groups of the glucose units attract water molecules.
Hydrated Storage: In muscle and liver cells, glycogen is stored in a hydrated form, with roughly 3 to 4 grams of water per gram of glycogen.
Water Weight Fluctuations: The water stored with glycogen is responsible for the rapid, temporary weight loss on low-carb diets and the subsequent weight regain when carbohydrates are reintroduced.
Osmotic Regulation: Storing glucose as glycogen helps regulate the cell's osmotic balance by reducing the number of free solute molecules in the cytoplasm.
Metabolic Availability: The highly branched structure of glycogen, and its association with water, allows for rapid mobilization of glucose when energy is needed, particularly during exercise.
Athletic Performance: The water-binding capacity of glycogen is the basis for carbohydrate-loading strategies used by endurance athletes to maximize fuel availability.
Glycogenolysis and Hydration: When glycogen is broken down for energy, the stored water is released, which helps contribute to the body's hydration, especially during prolonged activity.

The Hydrophilic Nature of Glycogen

Glycogen is a large, highly branched polysaccharide composed of glucose units. Its structural composition is the primary reason it bonds with water. The numerous hydroxyl (-OH) groups on the glucose molecules are polar, meaning they have a slight negative charge on the oxygen atom and a slight positive charge on the hydrogen atom. Water, being a polar molecule itself, is strongly attracted to these hydroxyl groups, forming hydrogen bonds.

This robust attraction causes water molecules to cluster around the glycogen molecule, a phenomenon known as hydration. The more glucose units that are chained together and branched, the more surface area is available for hydrogen bonding, increasing the amount of water stored with the glycogen. This is why glycogen, though only slightly soluble in water, is stored within cells in a hydrated form.

The Mechanism of Water Binding

The binding of water to glycogen occurs through intermolecular hydrogen bonds. These are different from the stronger, intramolecular covalent bonds that link the glucose units together within the glycogen molecule.

Hydrogen Bonding: The partially positive hydrogen atoms of water molecules are attracted to the partially negative oxygen atoms of the hydroxyl groups on the glycogen's glucose units.
Granule Formation: Glycogen is not stored as a single, massive molecule but in large granules within the cytoplasm of cells, particularly in the liver and muscles. The water is entrapped within and around these granules.
Structural Role: The branching structure of glycogen is crucial for its hydration. More branching means more non-reducing ends, which means more surface area for water molecules to bond to. This also makes it a more accessible energy source, as enzymes can break down glucose from multiple points at once.

The Physiological Significance of Glycogen Hydration

The relationship between glycogen and water has profound physiological implications, especially concerning body weight and cellular function. The storage of glycogen with water is an essential process, but it also explains common weight fluctuations.

Weight Fluctuations: Athletes and individuals following low-carbohydrate diets often experience rapid weight loss. This is primarily due to the body depleting its glycogen stores, causing the release of the associated water, which is then excreted. When carbohydrate consumption is resumed, glycogen is replenished, and the water weight returns.
Osmotic Balance: Storing glucose as large, complex glycogen molecules with bound water helps maintain the cell's osmotic balance. If the same amount of glucose were stored as individual, smaller molecules, it would significantly increase the intracellular solute concentration, drawing in an excessive amount of water and potentially causing the cell to burst.
Metabolic Availability: The hydrated state of glycogen granules allows them to be quickly accessed for energy. When glucose is needed, enzymes rapidly break down the glycogen, and the water is simultaneously released, helping with overall hydration during strenuous activity.

Glycogen and Water Storage: Muscle vs. Liver

Glycogen is primarily stored in the skeletal muscles and the liver, though its function differs between the two locations.


Feature	Muscle Glycogen	Liver Glycogen
Primary Function	Fuel source for the muscle cell during exercise.	Glucose reservoir for the entire body to maintain blood sugar levels.
Storage Capacity	Stores the largest total amount of glycogen in the body.	Stores a smaller, but vital, amount of glycogen.
Water Ratio	Each gram of glycogen stores about 3–4 grams of water.	Each gram of glycogen also stores about 3–4 grams of water.
Fate of Released Glucose	Used locally by the muscle cell for energy due to the lack of the enzyme glucose-6-phosphatase.	Released into the bloodstream to regulate blood glucose levels for other organs, especially the brain.

The Breakdown of Glycogen and Water Release

When the body needs a quick source of energy, such as during intense exercise or periods of fasting, it breaks down glycogen in a process called glycogenolysis. As the glycogen molecule is cleaved into individual glucose units, the hydrogen bonds with water are broken, and the stored water is released.

This release of water is a significant factor in the rapid initial weight loss seen on low-carbohydrate diets. The body first uses up its readily available glycogen stores before transitioning to fat metabolism. As the glycogen is utilized, the associated water is no longer needed for storage and is excreted from the body. Conversely, reintroducing carbohydrates leads to the re-hydration of glycogen stores and a subsequent increase in body weight.

The Role of Glycogen in Athletic Performance

The binding of glycogen with water is critically important for athletic performance, especially in endurance sports. Athletes often employ a strategy called carbohydrate loading to maximize their glycogen stores, and thereby, the amount of fuel available during a race or event. This practice leads to a temporary increase in body weight due to the extra water stored with the supercompensated glycogen. While this may seem counterintuitive for a sport requiring a lean frame, the performance benefits from having a larger fuel reserve outweigh the slight increase in body mass.

Conversely, during prolonged exercise, the depletion of muscle glycogen stores can lead to fatigue, a state often referred to as "hitting the wall". The subsequent breakdown of glycogen and release of water can also help with hydration during the exercise itself. For more on the role of glycogen in sports nutrition, see this review on glycogen metabolism for athletes.

Conclusion

Yes, glycogen bonds with water through hydrogen bonding, and this molecular relationship is fundamental to how the body stores and manages glucose. For every gram of glycogen, approximately 3 to 4 grams of water are co-stored, a process that explains rapid changes in body weight during dietary shifts like carbohydrate loading or low-carb diets. This hydration also plays a crucial role in maintaining cellular osmotic balance and providing readily available energy for muscles and the rest of the body. Far from a simple storage mechanism, the hydrophilic nature of glycogen is a sophisticated physiological feature with important implications for overall health and athletic performance.

Frequently Asked Questions

Each gram of stored glycogen is bound to approximately 3 to 4 grams of water within the body's cells.

The rapid initial weight loss on a low-carb diet is largely water weight. As your body uses up its glycogen stores, the water bound to it is released and excreted.

No, the water is held by weaker intermolecular hydrogen bonds, not the stronger covalent bonds that link the glucose molecules within the glycogen polymer itself.

Yes, for endurance athletes, the temporary weight gain from carbohydrate loading (and the extra water) is seen as beneficial because it maximizes the body's energy reserves for a long event.

Yes, as the body breaks down glycogen for energy, the associated water is released, which can contribute to overall body hydration, especially during prolonged exercise.

Storing glucose as a large glycogen molecule prevents it from disrupting the cell's osmotic balance, which could cause cellular damage or death if there were too many free glucose particles.

While small amounts are found in other tissues, the vast majority of glycogen is stored in the liver and skeletal muscles. The function of glycogen differs between these two locations.