What is glycogen?
Glycogen, which is the stored form glucose, is made up many glucose molecules.
Your body’s primary source of energy is glucose (sugar). It is found in carbohydrates (a macronutrient), certain foods, and liquids. Your body stores glucose in your muscles and liver, which is used to store glucose for later use.
Through a process known as glycogenesis, your body creates glycogen by using glucose. Glycogenolysis is a process where glycogen is broken down by the body for its use. These two processes are performed by several enzymes.
An enzyme is a protein that acts as a catalyst to allow certain bodily processes and functions to occur. Your body has thousands of enzymes that perform important functions.
What is the difference between glycogen and glucose?
Although they are all closely related to how your body uses carbohydrates as its primary source of energy, glucagon, glucose, and glycogen all serve different purposes.
The carbohydrates in your food provide glucose. Your blood sugar (blood glucose) is the main sugar in your body. This sugar is an important energy source and provides nutrients for your body’s muscles, organs, and nervous system. Because glucose is the main source of energy for your mind, it is vital. Your brain is constantly in need of glucose. Therefore, the recommended daily allowance for carbohydrates (RDA) for adults is at least 130g per day.
Your body stores glucose in your liver and muscles when it doesn’t require it immediately.
Your pancreas releases glucagon, which triggers glycogen to be converted back into glucose. It then enters your bloodstream to provide energy. Your body’s blood glucose levels are controlled by insulin and glucagon.
Is glycogen a carbohydrate?
Glycogen is derived from carbohydrates (a macronutrient), however it is not technically a carbohydrate. Your body converts carbohydrates into glucose when you consume foods or drink fluids that contain them. Glycogen, the stored form of glucose, is what we call it. It is made up of many glucose molecules that are connected.
Where is glycogen stored
Glycogen is stored mainly in your liver, skeletal muscles (the muscles attached your bones and to your tendons), and in small quantities in your brain.
Your liver stores more glycogen than your muscle skeletal muscles, but your total muscle mass is higher than that of the liver. This means that about three quarters of your body’s total glucose is stored in your muscles.
The glycogen levels in active muscles cells can be significantly reduced by prolonged and intense exercise. The amount of glycogen found in your liver cells can vary throughout the day depending on several factors.
* The amount of carbohydrates you eat.
* The time between meals.
* The duration and intensity of your most recent exercise.
The liver glycogen is nearly exhausted after fasting for 12-24 hours.
What is glycogen’s function?
Glycogen can have different functions and uses depending upon where it is stored, such as in your liver or muscles.
Glycogen storage in the liver
To regulate blood sugar (sugar), your body uses primarily the glycogen stored in your liver.
Normal blood glucose regulation is done by your body using the hormones insulin and glucagon. Your pancreas releases more glucose if your blood glucose levels drop too low (hypoglycemia). In part, glucagon triggers your liver to convert glycogen back into glucose so that it can enter your bloodstream. This is known as glycogenolysis. Your body can use glucose for energy when it has glucose in its bloodstream.
Your liver stores glycogen which partially aids in muscle activity and exercise. Your liver starts to break down glycogen when you start exercising. This is because your muscles are using it for energy. Your muscles, however, rely on their glycogen stores for energy.
Glycogen stores in muscle function
Muscle glycogen is primarily used to provide metabolic fuel for your muscles.
To move, your muscles require a lot of energy. Your body would soon run out of glucose if your muscles depended solely on glucose from your bloodstream.
This is because your body stores three quarters of your total glycogen within your skeletal muscles, ensuring that they have an adequate supply of energy during exercise without affecting your blood glucose levels.
Your exercise intensity is the main factor in determining the rate at the which muscle glycogen decreases. The higher the intensity, the faster your muscle glycogen runs out. High-intensity activities, such as sprinting repeatedly, can rapidly lower the glycogen stores of active muscle cells even though they may be short in duration.
When you eat enough carbohydrates, your muscles will be able to produce glycogen.
What is glycogen storage disorder (GSD)?
Glycogen storage disorder (GSD), a rare genetic condition that is passed down from one parent to the next, is where a person’s body is deficient in certain enzymes. GSD can be classified into several categories, as your body uses many enzymes to process glycogen. GSD can cause liver damage and muscle weakness. GSD can manifest in many forms, with symptoms often first appearing in infants and very young children.
What tests are used to check for glycogen levels?
There is no one test that measures glycogen levels. Your activity level and the amount of carbohydrates you consume throughout the day will affect your glycogen levels.
Healthcare providers instead use other tests to determine if your body is making or breaking down glycogen (glycogen store disease, GSD), if you have certain symptoms. These tests include:
* Blood tests: The liver function panel or kidney function panel can be used to check the health of these organs. A blood glucose level test can help detect if your body is using glycogen properly. GSD patients tend to have low blood sugar levels.
* Abdominal ultrasound: This test can be used to determine if your liver has enlargement.
* Tissue biopsy: To determine the amount of enzymes or glycogen in your tissue, your provider might take a sample from your liver or muscle.
* Genetic testing: Your provider may recommend genetic testing to determine if you have a gene that causes glycogen storage disease.
Note from Cleveland Clinic
Glycogen is vital for regulating blood sugar and providing energy during exercise. Glycogen is a very rare issue. You can make sure that you eat enough carbohydrates each day to maintain your glycogen levels. This is especially important for athletes. If you have any questions regarding your diet or your exercise goals, talk to your healthcare provider.
