Glycogen is the storage form of glucose in the liver, so when excess carbohydrate is ingested and converted to glucose, beyond that which is required for immediate utilisation as energy, instead of being wasted it is converted into a polymer of glucose and this is called glycogen. This process actually occurs within the liver itself and is called glycogenesis.
The liver is able to store approximately 100g of glucose in the form of glycogen which is equivalent to 400 calories worth of energy. This figure is actually very important because it is the equivalent of doing 30 minutes of cardiovascular exercise and is the rational of Point 3 of the Nysteia Formula namely to deplete the liver of its glycogen stores after an overnight fast.
Thus requiring the body to invoke the usage of its alternative energy source, namely fatty acids, by the process of lipolysis which is the natural breakdown of stored adipose tissue into fatty acids which are then taken up by individual cells for utilisation as energy. This is an absolutely essential step in the management of obesity.
If there is any remaining glycogen in the liver then this will be first broken down by a process called glycogenolysis into individual glucose molecules which will then be utilised as a primary energy source. Lipolysis will not take place largely until glycogen has been depleted.
It certainly won’t take place whilst both blood glucose and glycogen are constantly replenished, which of course happens every time more carbohydrate is ingested. This explains the rational of limiting carbohydrate intake in the diet throughout the eating window in Point 1 of the Nysteia Formula.
Both glycogenesis and glycogenolysis are under the direct control of some very important hormones namely insulin, glucagon and adrenaline. Insulin’s primary function is to control blood glucose and glucose metabolism by pushing glucose from the blood into cells for immediate utilisation. It also promotes glycogenesis.
Insulin is released form the pancreas when the blood glucose rises which happens after ingesting a carbohydrate meal and to a lesser extent a protein meal. There is very little insulin response following the ingestion of fat.
Conversely both glucagon and adrenalin promote the breakdown of glycogen from the liver into its constituent glucose molecules during periods when blood glucose is at its baseline level or during periods when glucose is likely to be required for immediate energy release such as mark physical exertion.