What is Ketogenesis?

Ketogenesis (1, 2) is a biochemical process that produces ketone bodies by breaking down fatty acids and ketogenic amino acids. The process supplies the needed energy of certain organs, especially the brain.

Not having enough ketogenesis could result to hypoglycaemia and over production of ketone bodies leading to a condition called ketoacidosis. It releases ketones when fat is broken down for energy. There are many ways to release ketones such as through urination and exhaling acetone. Ketones have sweet smell on the breath. (3)

Ketogenesis and ketoacidosis are entirely different thing. Ketoacidosis is associated with diabetes and alcoholism, which could lead to even serious condition like kidney failure and even death.

Ketogenic pathway image

Picture 1 : Ketogenic pathway
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A pyramid of ketogenic diet.picture
Image 2 : A pyramid of ketogenic diet
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What are Ketone bodies?

Ketone bodies are water soluble molecules produced by the liver from fatty acids during low food intake or fasting. They are also formed when the body experienced starvation, carbohydrate restrictive diet, and prolonged intense exercises.

It is also possible in people with diabetes mellitus type 1. The ketone bodies are picked up by the extra hepatic tissues and will convert to acetyl-CoA. They will enter the citric acid cycle and oxidized in the mitochondria to be used as energy. Ketone bodies are needed by the brain to convert acetyl-coA into long chain fatty acids.

Ketone bodies are produced in the absence of glucose. (1, 2, 3) It is easy to detect the presence of ketone bodies. Just observe the person’s breath. The smell of the breath is fruity and sometimes described as a nail polish remover-like. It depicts the presence of acetone or ethyl acetate. The ketone bodies include the following: (4)

  • Acetone – It can be converted by the liver into β-hydroxybutyrate,
  • Acetoacetic acid
  • Beta-drydroxybutyrate
  • Beta-ketopentanoate
  • Beta-hydroxypentanoate

The uses of Ketone bodies

  • Ketone bodies can be used as fuels for the brain, heart, and muscles.
  • It is the energy source for the brain during starvation.(5)

Testing For Ketone Bodies

  • If you are suffering from diabetes mellitus, then a routine monitoring for ketone bodies should be done. A strict monitoring is required for pregnant women. (5, 6)
  • Blood ketone test – A blood ketone test is used to determine the presence of ketones in the body. A blood sample is needed which can be taken from the arms of finger stick.
  • Urine test – The level of ketone in the body can be checked through the urine but is not that accurate because it will take a while for the ketone to pass through the system. You can buy a readily available urine ketone testing kit. You need to provide a clean catch urine sample and dip the dipstick in the urine. Changes in the color of the stick indicates the presence of ketone bodies.

Ketogenesis symptoms

  • Fruity smelling breath or nail polish remover like breath
  • Excessive thirst
  • Stomachache
  • Shortness of breath or rapid breathing
  • Frequent urination
  • Nausea with or without vomiting
  • Body weakness and a feeling of fatigue
  • confusion

How are Ketones metabolized?

For the ketones to be metabolized, it needs to undergo synthesis and breakdown. When the body is in its fasting state, the liver switches to fatty acid oxidation and ketone body production. The ketone generated in the liver will enter the bloodstream and will be used by other organs like the heart, brain, kidney cortex, and the skeletal muscles.

The brain does not have substantial non-glucose derived energy source and so it will primarily rely on ketone bodies. Ketones are always present in the blood but in a small amount. It is during the fasting state that the level of ketones increases. (8, 9)

Once the ketones are build up in the blood, they will spill over into the urine. Elevated ketone level in the blood is known as ketosis and presence of ketone bodies in the urine is known as ketonuria. Excess ketones can be removed from the body through the lungs.

It is the reason why you are experiencing a fruity smell breath. Blood ketones are usually elevated in patients with diabetes. A high level of ketone bodies is produced as a body’s response to low insulin level.

Ketogenic diet

The ketogenic diet is high in fat, low in carbohydrate and moderate in protein. If the carb is reduced, the fat increases and will enter the metabolic state called ketosis. The body will turn fats into ketones which supply energy to the brain.

In the ketogenic diet, the body has a low level of insulin, which is responsible for various health benefits to the body. It helps in losing weight. It helps you lose fat while preserving muscle mass.

It significantly improves the markers of diseases. A ketogenic meal includes natural fats like butter, coconut oil, and olive oil, a small amount of protein, and some green leafy vegetables (8,9).

Ketogenic diet is helpful in the treatment of epilepsy in children (10, 11) as well in adults. This particular form of diet is also helpful in altering the growth of cancer cells and improving the quality of life of patients suffering from cancer.

Ketogenic diet helps prevent hypoglycaemia, sugar cravings, and food fixations. It helps you control your food cravings. It dampens your appetite. You will less likely feel the urge to eat, which is helpful in people who want to lose weight.

Ketogenic diet is helpful in reducing high blood pressure (10). It also helps in significantly reducing the level of cholesterol in the blood. Over time, it improves the condition of the arteries, which also improves the arterial system in the body. Ketogenic diet improves the health and function of the brain.

Ketones are water soluble fats, which can freely cross and feed your brain. Under ketogenic diet, you will notice a significant improvement in the cognitive and mental acuity. It reduces migraine frequency and lowers the use of pain medication for migraine. It is also helpful in the treatment and management of traumatic brain injuries.

It helps reduce brain swelling, speeds up the recovery process, and improve the motor functions of the brain. Ketogenic diet is more effective in younger group age than old aged patients.


  10. The Ketogenic Diet: A Complete Guide for the Dieter and Practitioner By Lyle McDonald
  11. Ketogenic Diet: A Treatment for Children and Others with Epilepsy By John M. Freeman, Professor of Neurology and Pediatrics John M Freeman, MD M.D.

Published by Dr. Rajesh MD under Diabetes Information.
Article was last reviewed on January 8th, 2022.

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