The ketogenic diet

Ketosis, a specific, fully physiological metabolic state in healthy individuals. There have always been two ways of inducing ketosis: either fasting or a diet heavy in fats and proteins. It is now possible to implement a ketogenic diet with the use of gluten-free foods. Eliminating sugars causes the body to produce ketones to use as an energy source. Ketone bodies are molecules produced by the mobilisation and combustion of fatty acids when their quantity is elevated or when less glucose is available (this is where the definition " ketogenic" originates from). If you follow a ketogenic diet (minimal carbohydrate content) the body must derive energy from triglycerides and, owing to the shortage of glucose, fatty acids derived from triglycerides are transformed into ketone bodies.

The biomechanical mechanism
How does it work?

When you eat carbohydrates, whether starches or simple sugars, the body burns the glucose contained in these foods to obtain energy. The glucose obtained from the foods is used to produce energy, and part of it is stored as glycogen in the liver and muscles (through insulin). Excess glucosewhich is not stored as glycogen or used immediately is transformed into body fat. When energy production is needed, the stored glycogen is re-converted into glucose and used directly or transported by the blood to be used in other cells in the body. As glucose and glycogen are not available for use in energy production on a ketogenic diet, the body will obtain energy by breaking down the fatty acids present in food and in fat stored in the body. Therefore the body will begin to burn its reserve stores of fat in order to produce the energy it needs.



The pancreas is the organ that carries out various exocrine and endocrine digestive functions.

One of the hormones the pancreas produces is insulin.

Insulin is the hormone that allows glucose to enter the cells.

The glucose undergoes three processes:

it is used by the cells in a measure equal to the immediate energy the body needs;

any excess is transformed into glycogen by the liver and muscles and is stored as energy reserves;

the excess is transformed into body fat.

An excessive introduction of simple and complex sugars creates greater production of insulin so it can convey glucose to the cells.

This is defined as the condition hyperinsulinemia which, if it functions to absorb nutrients after a meal, can cause other conditions if excessive or takes place over an extended period of time.

To a large extent, obese individuals suffer from hyperinsulinism, or excessive secretion of insulin, which as well as increasing the "efficiency" with which we store fat in cells also causes compulsive cravings for carbohydrates, causing excessive and continued consumption.

Over the long term, this hyperinsulinism reduces the effectiveness of insulin.

In this way the condition of insulin resistance may be created, where more and more insulin is needed in order for glucose to enter the cells. As a consequence, excess insulin performs its role in glucose metabolism but also blocks the process of mobilisation of fat (lipolysis) and increases fat accumulation processes (lipid synthesis), intermediates in the process of formation of fats further block the lipolysis mechanism.

In the end, insulin resistance leads to a chronic increase in blood sugar levels or in type 2 diabetes mellitus. This type of diabetes is more common and is connected with being overweight and with hypernutrition, or overfeeding, in a type of vicious circle. Chronic hyperglycaemia, or high blood sugar, leads to a series of associated conditions which range from cardiovascular to microcirculatory (retinopathy), renal, nervous, etc.

Ketone bodies and physiological ketosis.

During a fast or a ketogenic diet, low levels of insulin and glucose, together with an elevated quantity of fats provoke the formation of ketone bodies. Ketone bodies are: acetoacetic acid, beta-hydroxybutyric acid and acetone. These molecules are able to penetrate the blood-brain-barrier surrounding the brain and supply it with energy (something fats cannot do; the brain normally uses glucose), while being used as an energy source by other tissues at the same time. This state of ketosis, which should never be confused with ketoacidosis, is an evolutionary advantage that has allowed humans to survive periods of famine. It was one of the greatest biochemists of all time, Hans Krebs, who, as far back as 1966, defined ketosis as physiological (differentiating it from the medical condition of ketoacidosis present in diabetes).

Share by: