It seems the world is dieting — again — and this time it’s all about “banting”. Besides being an undertaker, William Banting is known for being the first to popularise a weight loss diet based on limiting intake of refined and easily digestible carbohydrates. (http://en.wikipedia.org/wiki/William_Banting)
But, this article is not about “Banting”, or dieting, per say – it’s simply about understanding a few processes in our body, and, understanding the difference between Diabetic Ketoacidosis and this Nutritional Ketosis that everyone is trying to achieve!
Glycogen – Glycogen is the storage form of glucose in our body. IT IS NOT GLUCOSE. Glycogen is stored in the liver and the muscles of the body.
The liver contains an enzyme called glucose-1-phosphatase, which enables glycogen to be broken down to glucose, and exported from the liver into the bloodstream.
Muscles do not possess this enzyme therefore, glycogen from the liver is available to the brain as glucose. Glycogen from the muscle is not – it must be used by the muscle.
The ability of the liver and the muscles to store carbohydrates (as glycogen) is limited. Excess carbohydrates that cannot be stored as glycogen, or used immediately, are stored as fat in the form of triglycerides.
Glycogen is stored in the liver for about 24 hours.
Ketones – Ketones are water soluble molecules that are produced as by-products when fatty acids are broken down for energy in the liver during periods of low food intake or carbohydrate restriction. Ketones are produced for cells of the body to use as energy instead of glucose.
These ketone “bodies” – acetone, acetoacetic acid (acetoacetate), and beta-hydroxybutyric acid (β-hydroxybutyrate – BHB) – are released into the bloodstream, taken up by the brain and other organs, shuttled into the mitochondria (“energy factory” of cells ) and used up as fuel.
In a normal functioning body, excess BHB and acetoacetate are excreted through the urine (ketonuria), while acetone is excreted via the urine or is breathed out, hence the characteristically sweet “keto breath” (and there is nothing “sweet” about the foul smell of “keto breath”)!
Two of the three ketones are used as a source of energy in the heart and brain while the third (acetone) is produced from the degradation/breakdown of acetoacetic acid. Both acetoacetate and beta-hydroxybutyrate are acidic, and, if levels of these ketone bodies are too high, the pH of the blood drops, resulting in ketoacidosis.
The heart preferentially utilises fatty acids for energy under normal physiologic conditions. However, under ketotic conditions, the heart can effectively utilise ketone bodies for energy.
Our brain can only function with glucose and ketones. Fortunately, our liver can take fat and select amino acids (the building blocks of proteins) and turn them into ketones, first and foremost to feed our brain.
- When there aren’t enough carbohydrates to produce glycogen storage, the body changes from relying on glycogen as its main source of energy, to relying on fat as its main energy source. This process creates ketones.
- Any production of ketones is called ketogenesis.
- When excess ketone bodies accumulate, this abnormal (but not necessarily harmful) state is called ketosis.
- An increased acidity in the blood pH and other body tissue is called acidosis. There are two types of acidosis – metabolic and respiratory. Metabolic acidosis occurs when your kidneys can’t get rid of acid build-up or when your body gets rid of too much base (bases neutralise acids, and vice versa). Respiratory acidosis occurs when your lungs do not properly eliminate the carbon dioxide (CO2). When CO2 builds up in your blood, it becomes more acidic. Acidosis is often referred to as the “kiss of death“.
- Uncontrollable ketosis that leads to a sharp, and potentially fatal, increase in the acidity of the blood such that the body’s pH is lowered to dangerously acidic levels is called ketoacidosis
- When a diabetic fails to receive enough insulin, they effectively go into a state of starvation. While they may have all the glucose in the world in their bloodstream, without insulin, they can’t get the glucose into their cells. Hence, there cells are effectively going into starvation. The body does what it would do in anyone – it starts to make ketones out of fat and proteins for energy. Because a diabetic body cannot produce insulin, there is no “feedback loop” as with a normal functioning body, and so a diabetic will continue to produce more and more ketones without stopping. The resulting extremely high levels of blood glucose, and ketone bodies, lowers the pH of the blood leading to SEVERE acidosis and triggers the kidneys to attempt to excrete the glucose and ketones.This osmotic diuresis of glucose will cause further removal of water and electrolytes from the blood resulting in potentially fatal dehydration, tachycardia (increased heart beat) and hypotension (low blood pressure). This can lead to advanced Diabetic Ketoacidosis, which can lead to “diabetic coma” and potential death. This combination of circumstances that leads to a life-threatening acidosis is called Diabetic ketoacidosis (DKA)
- DKA is not usually possible in a person who can produce insulin, even in small amounts. The reason is that a “feedback loop” prevents the ketone level from getting high enough to cause the change in pH that leads to the cascade of bad problems as in DKA. A person who is said to be “keto-adapted,” or in a state of nutritional ketosis, generally has ketone levels that are far lower than the levels required to cause harm through acid-base abnormalities.
So, you have now completed “Ketosis 101”. Only one last pointer. If you go overboard and eat too much protein i.e. more than the body needs, some of the amino acids in the protein will be turned into glucose via a process called gluconeogenesis. This will reduce the body’s ability to burn fat and may hinder fat loss, particularly if your goal is ketosis for weight loss.