What does glycogen mean?
Glycogen is a highly branched polysaccharide used by animals, especially humans, to store glucose. It is found in substantial amounts in the liver and muscles, with smaller deposits in other tissues. The liver uses stored glycogen to help maintain blood glucose between meals, while muscle glycogen provides fuel for movement and vigorous activity. When energy is required, glycogen is broken down and its glucose units become available for use. In nutrition and exercise science, the size of glycogen stores can be discussed in relation to diet, endurance, fatigue, and recovery. Unlike starch, which is the chief storage carbohydrate in plants, glycogen is the principal carbohydrate reserve of animals. The word belongs primarily to technical and biological vocabulary, although it is also familiar from accounts of athletic performance and metabolic health.
nounA highly branched polysaccharide that stores glucose in animals, especially in the liver and muscles. It is broken down when the body needs readily available energy.
- A branched polysaccharide that functions as a storage form of glucose, particularly in animal liver and muscle tissue.
"The liver replenished its glycogen stores after the meal."
"Exercise depleted the muscle glycogen needed for prolonged activity."
"The researchers measured how liver glycogen levels changed after feeding."
The plural is rare; glycogen is normally used as a mass noun.
"The researchers compared glycogens from liver and muscle tissue."
Your liver and muscles keep a rapid-access reserve of sugar in the form of glycogen, ready when energy is needed.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does glycogen come from?
The term was formed in the 19th century from Greek glykys, meaning “sweet,” and the combining element -gen, meaning “producing” or “forming.” Its name reflects its role as a stored form of sugar. Related words in English, including glucose, glycoside, hyperglycemia, and hypoglycemia, share the Greek sweet or sugar-root.
Related word forms
How glycogen is actually used
Technical and scientific; in general usage, glycogen is encountered mainly in discussions of metabolism, nutrition, fasting, and exercise physiology.
Easily confused with glycogen
Glucose is a simple sugar used by the body for energy, whereas glycogen is a branched polymer in which many glucose units are stored.