Table of ContentsView AllTable of ContentsStructureMetabolismExerciseMaintenanceStorage DiseasesFrequently Asked Questions
Table of ContentsView All
View All
Table of Contents
Structure
Metabolism
Exercise
Maintenance
Storage Diseases
Frequently Asked Questions
Glycogen is a branchedpolysaccharide(also called a polycarbohydrate) composed of many glucose molecules linked together. It is the primary storage form of carbohydrates in the body and is mainly stored in the liver and skeletal muscle.
Your body can break down glycogen to release glucose into the bloodstream when you need a quick energy boost or when blood glucose levels drop.
The amount of glycogen stored in the body can depend on several factors, including diet, fitness level, and body mass.
This article will explore what glycogen is and the important roles it has in the body. It will also discuss how to maintain glycogen levels.
SCIEPRO/SCIENCE PHOTO LIBRARY / Getty Images
Glycogen Structure
A fully formed glycogen molecule is believed to contain around 55,000 glucose units. Every glycogen molecule also has glycogenin, a protein involved in glycogen synthesis.
Glycogen is stored in the liver, fat cells, and muscle in a hydrated form that consists of three to four parts water and 0.45 millimoles of potassium per gram of glycogen.
Glycogen Function
Excess glucose gets stored short term in the liver and muscles as glycogen or long term as fat.
Liver glycogen acts as a reservoir for your body’s glucose to help maintain normal blood glucose levels.
When you eat a meal containing carbohydrates, glucose levels in the blood rise, triggering thepancreasto releaseinsulin, a hormone that pulls glucose into cells to be used for fuel or stored for future use. Insulin also acts on liver cells to activate enzymes, including glycogen synthase, which links chains of glucose units together.
When we need additional energy, enzymes break down glycogen to supply the body with glucose.
Glucose broken down from liver glycogen is the body’s main source of energy. Unlike glycogen stored in the liver that can be distributed throughout the body, glycogen stored in the muscles is only used to fuel the muscles themselves. This is because muscle cells do not produce the enzyme glucose-6-phosphatase, which is needed to release glucose into the bloodstream.
Glycogen has also been identified in other tissues in the body, including the heart, brain, fat tissue, red blood cells, and kidney. However, its functions in these areas are largely unknown.
How Much Glycogen Do I Have?The average total body glycogen content is 600 grams, with about 500 grams being stored in muscle and 80 grams in the liver.
How Much Glycogen Do I Have?
The average total body glycogen content is 600 grams, with about 500 grams being stored in muscle and 80 grams in the liver.
Glycogen Metabolism
The two main metabolic pathways of glycogen are glycogenesis and glycogenolysis. In short, glycogenesis is the formation of glycogen from glucose molecules. Glycogenolysis, on the other hand, is the breakdown of glycogen into glucose molecules.
Glycogenesis
Glycogenesis is the process of forming glycogen from glucose. Glycogen is produced depending on the body’s demand for energy and glucose. The synthesis of glycogen requires energy from the high-energy nucleotide uridine triphosphate (UTP).
Next, phosphoglucomutase triggers the phosphate group transfer from carbon 6 to carbon 1, which converts glucose-6-phosphate into glucose-1-phosphate.
After a chain of at least 10 glucose molecules has been formed, the branching enzyme transfers a terminal segment of at least six glucose molecules from a nonreducing end of the glycogen chain to another glucose molecule, where it is joined with an alpha-1,6 bond.
Glycogenolysis
Glycogenolysis is the enzymatic process that occurs when glycogen breaks down into glucose to maintain blood glucose levels during fasting and fuel muscle contractions. It primarily takes place in liver and muscle cells.
From there, glucose-1-phosphate can enter the glycolytic pathway. If glucose-6-phosphatase is present, free glucose can be formed and released into the bloodstream. This process can happen in the liver but not in the muscle in which glucose-6-phosphatase is absent.
Because glycogen phosphorylase cannot cleave glucose from branches, a debranching enzyme is required to transfer glucose to the linear chain to degrade the branches.
Glycogen and Exercise
Glycogen stores in the muscle and liver decline during physical activity. Athletes who participate in activities that burn many calories, such as long-distance running or cycling, may experience a depletion of glycogen if they do not consume enough carbohydrates. As a result, a person may experience fatigue, weakness, and decreased performance.
Maintaining Glycogen Levels
There are also additional strategies to help maintain glycogen levels, including:
What Happens When Your Body Runs Out of Glycogen?When glycogen stores become depleted, your body will begin to metabolize fat for energy.
What Happens When Your Body Runs Out of Glycogen?
When glycogen stores become depleted, your body will begin to metabolize fat for energy.
Glycogen Storage Diseases
The most common types are:
Symptoms of GSD include:
Summary
Glycogen is a multibranched polysaccharide that is the stored form of glucose in the body. It is mainly synthesized in the liver and muscle cells. Glycogen is a readily available form of glucose and can provide rapid energy when needed. It also plays a role in maintaining our blood glucose concentration.
The two main metabolic pathways of glycogen are glycogenesis (the formation of glycogen from glucose molecules) and glycogenolysis (the breakdown of glycogen into glucose molecules).
A Word From Verywell
Glycogen plays an important role in keeping your body fueled. Glycogen levels vary depending on your diet, body mass, and exercise frequency. If you find yourself exhausted during a high-intensity workout or endurance training, your glycogen levels may be depleted. It’s important to consume sufficient amounts of carbohydrates to replenish your glycogen stores to maintain training intensity and energy levels.
The best foods to build up glycogen levels are starchy vegetables, fruit, and whole-grains such as oatmeal, quinoa, and brown rice.
Glycogen plays a key role in keeping our muscles fueled during exercise. It also helps maintain healthy blood sugar levels.
22 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Adeva-Andany MM, González-Lucán M, Donapetry-García C, Fernández-Fernández C, Ameneiros-Rodríguez E.Glycogen metabolism in humans.BBA Clinical.2016;5:85-100. doi:10.1016/j.bbacli.2016.02.001Nemours Children’s Health.Glycogen.Murray B, Rosenbloom C.Fundamentals of glycogen metabolism for coaches and athletes.Nutr Rev. 2018;76(4):243-259. doi:10.1093/nutrit/nuy001Science Direct.Glycosidic Bond.Bezborodkina NN, Chestnova AYu, Vorobev ML, Kudryavtsev BN.Spatial structure of glycogen molecules in cells.Biochemistry Moscow.2018;83(5):467-482. doi:10.1134/S0006297918050012Kreitzman SN, Coxon AY, Szaz KF.Glycogen storage: illusions of easy weight loss, excessive weight regain, and distortions in estimates of body composition.Am J Clin Nutr. 1992;56(1 Suppl):292S-293S. doi:10.1093/ajcn/56.1.292SMedlinePlus.Carbohydrates.Science Direct.Glucose.University of California.Diabetes Education Online.Colorado State University.Physiologic Effects of Insulin.Science Direct.Glycogen.Adeva-Andany MM, González-Lucán M, Donapetry-García C, Fernández-Fernández C, Ameneiros-Rodríguez E.Glycogen metabolism in humans.BBA Clin. 2016;5:85-100. doi:10.1016/j.bbacli.2016.02.001Science Direct.Glycogen Synthesis.Science Direct.Glycogenin.Science Direct.Glycogenolysis.Science Direct.Glucose-6-Phosphatase.Murray B, Rosenbloom C.Fundamentals of glycogen metabolism for coaches and athletes.Nutr Rev. 2018;76(4):243-259. doi:10.1093/nutrit/nuy001Jeukendrup A.A step towards personalized sports nutrition: carbohydrate intake during exercise.Sports Med. 2014;44(Suppl 1):25-33. doi:10.1007/s40279-014-0148-zKerksick CM, Arent S, Schoenfeld BJ, et al.International society of sports nutrition position stand: nutrient timing.J. Int. Soc. Sports Nutr.2017;14(1):33. doi:https://doi.org/10.1186/s12970-017-0189-4Carlsohn A.Aktuelle Ernährungsempfehlungen für Ausdauersportler.Dtsch Z Sportmed. 2016;2016(01):7-12. doi:10.5960/dzsm.2015.193Johns Hopkins.Glycogen Storage Disease.Children’s Hospital of Philadelphia.Glycogen Storage Disease.
22 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Adeva-Andany MM, González-Lucán M, Donapetry-García C, Fernández-Fernández C, Ameneiros-Rodríguez E.Glycogen metabolism in humans.BBA Clinical.2016;5:85-100. doi:10.1016/j.bbacli.2016.02.001Nemours Children’s Health.Glycogen.Murray B, Rosenbloom C.Fundamentals of glycogen metabolism for coaches and athletes.Nutr Rev. 2018;76(4):243-259. doi:10.1093/nutrit/nuy001Science Direct.Glycosidic Bond.Bezborodkina NN, Chestnova AYu, Vorobev ML, Kudryavtsev BN.Spatial structure of glycogen molecules in cells.Biochemistry Moscow.2018;83(5):467-482. doi:10.1134/S0006297918050012Kreitzman SN, Coxon AY, Szaz KF.Glycogen storage: illusions of easy weight loss, excessive weight regain, and distortions in estimates of body composition.Am J Clin Nutr. 1992;56(1 Suppl):292S-293S. doi:10.1093/ajcn/56.1.292SMedlinePlus.Carbohydrates.Science Direct.Glucose.University of California.Diabetes Education Online.Colorado State University.Physiologic Effects of Insulin.Science Direct.Glycogen.Adeva-Andany MM, González-Lucán M, Donapetry-García C, Fernández-Fernández C, Ameneiros-Rodríguez E.Glycogen metabolism in humans.BBA Clin. 2016;5:85-100. doi:10.1016/j.bbacli.2016.02.001Science Direct.Glycogen Synthesis.Science Direct.Glycogenin.Science Direct.Glycogenolysis.Science Direct.Glucose-6-Phosphatase.Murray B, Rosenbloom C.Fundamentals of glycogen metabolism for coaches and athletes.Nutr Rev. 2018;76(4):243-259. doi:10.1093/nutrit/nuy001Jeukendrup A.A step towards personalized sports nutrition: carbohydrate intake during exercise.Sports Med. 2014;44(Suppl 1):25-33. doi:10.1007/s40279-014-0148-zKerksick CM, Arent S, Schoenfeld BJ, et al.International society of sports nutrition position stand: nutrient timing.J. Int. Soc. Sports Nutr.2017;14(1):33. doi:https://doi.org/10.1186/s12970-017-0189-4Carlsohn A.Aktuelle Ernährungsempfehlungen für Ausdauersportler.Dtsch Z Sportmed. 2016;2016(01):7-12. doi:10.5960/dzsm.2015.193Johns Hopkins.Glycogen Storage Disease.Children’s Hospital of Philadelphia.Glycogen Storage Disease.
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
Adeva-Andany MM, González-Lucán M, Donapetry-García C, Fernández-Fernández C, Ameneiros-Rodríguez E.Glycogen metabolism in humans.BBA Clinical.2016;5:85-100. doi:10.1016/j.bbacli.2016.02.001Nemours Children’s Health.Glycogen.Murray B, Rosenbloom C.Fundamentals of glycogen metabolism for coaches and athletes.Nutr Rev. 2018;76(4):243-259. doi:10.1093/nutrit/nuy001Science Direct.Glycosidic Bond.Bezborodkina NN, Chestnova AYu, Vorobev ML, Kudryavtsev BN.Spatial structure of glycogen molecules in cells.Biochemistry Moscow.2018;83(5):467-482. doi:10.1134/S0006297918050012Kreitzman SN, Coxon AY, Szaz KF.Glycogen storage: illusions of easy weight loss, excessive weight regain, and distortions in estimates of body composition.Am J Clin Nutr. 1992;56(1 Suppl):292S-293S. doi:10.1093/ajcn/56.1.292SMedlinePlus.Carbohydrates.Science Direct.Glucose.University of California.Diabetes Education Online.Colorado State University.Physiologic Effects of Insulin.Science Direct.Glycogen.Adeva-Andany MM, González-Lucán M, Donapetry-García C, Fernández-Fernández C, Ameneiros-Rodríguez E.Glycogen metabolism in humans.BBA Clin. 2016;5:85-100. doi:10.1016/j.bbacli.2016.02.001Science Direct.Glycogen Synthesis.Science Direct.Glycogenin.Science Direct.Glycogenolysis.Science Direct.Glucose-6-Phosphatase.Murray B, Rosenbloom C.Fundamentals of glycogen metabolism for coaches and athletes.Nutr Rev. 2018;76(4):243-259. doi:10.1093/nutrit/nuy001Jeukendrup A.A step towards personalized sports nutrition: carbohydrate intake during exercise.Sports Med. 2014;44(Suppl 1):25-33. doi:10.1007/s40279-014-0148-zKerksick CM, Arent S, Schoenfeld BJ, et al.International society of sports nutrition position stand: nutrient timing.J. Int. Soc. Sports Nutr.2017;14(1):33. doi:https://doi.org/10.1186/s12970-017-0189-4Carlsohn A.Aktuelle Ernährungsempfehlungen für Ausdauersportler.Dtsch Z Sportmed. 2016;2016(01):7-12. doi:10.5960/dzsm.2015.193Johns Hopkins.Glycogen Storage Disease.Children’s Hospital of Philadelphia.Glycogen Storage Disease.
Adeva-Andany MM, González-Lucán M, Donapetry-García C, Fernández-Fernández C, Ameneiros-Rodríguez E.Glycogen metabolism in humans.BBA Clinical.2016;5:85-100. doi:10.1016/j.bbacli.2016.02.001
Nemours Children’s Health.Glycogen.
Murray B, Rosenbloom C.Fundamentals of glycogen metabolism for coaches and athletes.Nutr Rev. 2018;76(4):243-259. doi:10.1093/nutrit/nuy001
Science Direct.Glycosidic Bond.
Bezborodkina NN, Chestnova AYu, Vorobev ML, Kudryavtsev BN.Spatial structure of glycogen molecules in cells.Biochemistry Moscow.2018;83(5):467-482. doi:10.1134/S0006297918050012
Kreitzman SN, Coxon AY, Szaz KF.Glycogen storage: illusions of easy weight loss, excessive weight regain, and distortions in estimates of body composition.Am J Clin Nutr. 1992;56(1 Suppl):292S-293S. doi:10.1093/ajcn/56.1.292S
MedlinePlus.Carbohydrates.
Science Direct.Glucose.
University of California.Diabetes Education Online.
Colorado State University.Physiologic Effects of Insulin.
Science Direct.Glycogen.
Adeva-Andany MM, González-Lucán M, Donapetry-García C, Fernández-Fernández C, Ameneiros-Rodríguez E.Glycogen metabolism in humans.BBA Clin. 2016;5:85-100. doi:10.1016/j.bbacli.2016.02.001
Science Direct.Glycogen Synthesis.
Science Direct.Glycogenin.
Science Direct.Glycogenolysis.
Science Direct.Glucose-6-Phosphatase.
Jeukendrup A.A step towards personalized sports nutrition: carbohydrate intake during exercise.Sports Med. 2014;44(Suppl 1):25-33. doi:10.1007/s40279-014-0148-z
Kerksick CM, Arent S, Schoenfeld BJ, et al.International society of sports nutrition position stand: nutrient timing.J. Int. Soc. Sports Nutr.2017;14(1):33. doi:https://doi.org/10.1186/s12970-017-0189-4
Carlsohn A.Aktuelle Ernährungsempfehlungen für Ausdauersportler.Dtsch Z Sportmed. 2016;2016(01):7-12. doi:10.5960/dzsm.2015.193
Johns Hopkins.Glycogen Storage Disease.
Children’s Hospital of Philadelphia.Glycogen Storage Disease.
Meet Our Medical Expert Board
Share Feedback
Was this page helpful?Thanks for your feedback!What is your feedback?OtherHelpfulReport an ErrorSubmit
Was this page helpful?
Thanks for your feedback!
What is your feedback?OtherHelpfulReport an ErrorSubmit
What is your feedback?
