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Fuel Utilization In The Body: The Main Principle Of Keto

The body has three storage depots to use as fuel:

  • Carbohydrates from food
  • Protein that is converted to glucose in the liver and used for energy
  • Stored body fat and ketones

In a regular high carb diet, carbohydrates are the main source of fuel for the body.

  1. Carbohydrates, specifically starches and sugars are readily broken down into glucose in the bloodstream, giving the body its principal energy source.
  2. At this point, the hormone insulin steps in to remove glucose from the bloodstream as too much sugar can lead to a dangerous condition known as glycosylation.
  3. Insulin converts glucose into glycogen. Some glycogen is stored inside the liver as a fuel reserve for the brain, and the rest is stored in the muscles as fuel reserves for the body.
  4. When that muscle glycogen is not used through a lack of energy expenditure or exercise, it stays in the muscles.
  5. The human body can only store so much glycogen, about 1800 calories worth. When that reserve becomes full both the muscles and the liver send a signal to stop insulin production and excess glucose from dietary carbs begins to build up in the bloodstream, calling for more and more insulin to be released to remove it.
  6. Insulin levels surge, and eventually this leads to insulin resistance.
  7. At this point, the liver then sends any excess glucose to be stored as body fat.
  8. As high carb intake continues, glucose floods the bloodstream, insulin levels increase, and so do the body’s fat stores.



High Carb Intake = High Glucose In The Blood = High Insulin = Body Fat Stores

Eventually this leads to metabolic syndrome, a set of conditions caused by insulin resistance, which includes obesity, fatty liver, type 2 diabetes, heart disease, and other metabolic issues.

While this carb cycle may not occur in everyone, for many who are obese, have a sensitivity to carbs, or who do not expend the required amount of stored energy, this is often the case and the main culprit behind obesity.

Lipolysis And Ketosis

Under normal dietary conditions, ketones play no role in fueling the body and energy production, but during a Ketogenic low carb diet, ketones become the central player, fueling the body and at the same time flipping on the fat burning switch.

When the intake of carbs is limited, and their sources controlled, meaning that starches and sugars are eliminated, the body goes into a state called lipolysis, a most efficient biochemical pathway to weight loss and a scientifically proven alternative to using glucose for energy.

  • Lipolysis is the only practical alternative to giving the body an alternative for glucose fuel, the process that often leads to obesity
  • Lipolysis occurs when the body begins to burn fat stores for energy instead of carbohydrates that are obtained from the diet.
  • The by-products of this fat burning process are ketones and so ketosis is the secondary process of lipolysis.
  • By lowering intake of carbohydrates and also the sources of those carbohydrates, which the body will use for energy first when available, it is forced to use its fat stores instead, literally melting it off the body in a state referred to as ketosis.
  • Ketones, the byproduct of ketosis, fuel the body

Sugars, grains, starches, and starchy vegetables fuel your body when you eat them, a state called glucosis (a term coined by the late Dr. Atkins, a pioneer in low carb weight loss). It is only when you lower carb intake and limit it to non-starchy vegetables, and small amounts of certain dairy foods that you are not eating enough carbs to create glucose, creating a state of ketosis where the body begins to burn its fat stores for energy.

  • The only exception to the body not needing glucose for fuel is ketones

Lipolysis and its secondary process, ketosis provides adequate fuel for cells, the brain, and other organs just as glucose from carbs does BUT, unlike when the body uses glucose from carbs for energy, ketosis does not store fat, and actually allows the body to burn stored fat for fuel.


Ketosis Versus Ketoacidosis

Ketosis and ketoacidosis are often confused and they are two completely different things.

  • Ketosis is a natural fat burning process in the body, while ketoacidosis is a medical condition that occurs only in uncontrolled diabetes.
  • Ketoacidosis is dangerous, but ketosis on a ketogenic diet is perfectly normal, healthy, and necessary for weight loss.


Fuel Utilization By The Brain

According to Psychology Today, while the brain typically runs on glucose, it has no problems getting its fuel from ketones when they are available.


Lipolysis and the its secondary process, ketosis
uses fat as its primary source of energy.

Ketone production occurs when insulin in the bloodstream is low.

The lower the insulin level, the higher the ketone production and vice versa.

This process can only occur while following a low carb diet and the sources of those carbs are not insulin trigger foods, such as starches or sugars.

While some parts of the brain can only use glucose for energy, the body takes care of this too.

When glucose is lacking, it can turn protein into glucose through a process called gluconeogenesis.

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