Isn't Our Body Supposed to Run on Sugar?

author avatar Dr. Eric Berg 03/20/2024

Ketosis and how the body fuels itself are two intertwined, yet often misunderstood topics.

Learn about how the body switches between glucose, ketones, and fatty acids, and how gluconeogenesis turns non-carb sources into glucose.

The Body's Fuel Sources

Have you ever wondered how your body keeps going? The body can run on more than just glucose.

Understanding Glucose as a Fuel Source

Glucose, our primary fuel source, is derived from carbohydrates in our diet. This simple sugar provides immediate energy to cells throughout the body.

Dial set to ketones

Role of Ketones in Energy Production

Ketones are another vital player in this game. Produced by the liver during low carbohydrate intake or fasting periods, they serve as an alternative energy source for various tissues, including muscles and the brain.

Fatty Acids as an Alternative Energy Source

Last but certainly not least is fatty acids. When glucose levels are insufficient, your fat stores can be converted into usable energy through beta-oxidation.

Fat Storage and Its Purpose

Fat serves as our body's survival mechanism, bridging the gap between meals by serving as an energy source when no glucose is available.

The Science Behind Fat Storage

Our bodies are incredibly efficient at storing energy in the form of fat. This allows us to store energy as fat for times of food scarcity.

  1. Your body needs to have a reserve for times when food might be scarce. This was especially crucial during prehistoric times when hunting and gathering were unpredictable activities.

  2. When food is scarce, our body draws on stored fats to provide energy and insulation against cold temperatures.

  3. Stored fats provide insulation against cold temperatures, a handy feature if you live without modern heating.

How Does Our Body Utilize Stored Fat?

We know exercise burns calories, but where do those burned-off pounds go? The answer is simple: your body uses stored fat as fuel. When you work out, those extra pounds are being used up, aiding in keeping your body fit and healthy.

Gluconeogenesis - Making Glucose from Non-Carbohydrate Sources

Gluconeogenesis is a metabolic process in which the body synthesizes glucose from non-carbohydrate precursors, such as amino acids, lactate, and glycerol. This intricate pathway primarily occurs in the liver and, to a lesser extent, in the kidneys.

During periods of fasting, low carbohydrate intake, or intense exercise, gluconeogenesis plays a crucial role in maintaining blood glucose levels, ensuring a constant energy supply for vital organs, especially the brain.

The process involves a series of enzymatic reactions that convert these non-carbohydrate substrates into glucose, highlighting the body's ability to adapt and sustain glucose homeostasis under varying physiological conditions.

What Triggers Gluconeogenesis?

This fascinating process kicks in during fasting, starvation, or intense exercise. A low-carb diet also triggers it.

Impact of Diet on Gluconeogenesis

Your dietary choices play a crucial role here. Diets high in protein can stimulate this glucose-making pathway. Our bodies have an innate ability to adapt and survive under various conditions.

The process involves converting non-carbohydrates like fats and proteins into glucose - the essential fuel for many body parts.

Parts Of The Body That Run Only On Glucose

While various tissues and organs in the body can utilize different energy sources, the brain is particularly notable for its reliance on glucose.

Unlike many other tissues that can switch between glucose and alternative fuels, such as fatty acids, the brain has limited ability to use alternative substrates.

Under normal physiological conditions, the brain relies almost exclusively on glucose to meet energy demands.

This highlights the importance of maintaining stable blood glucose levels for proper brain function, as disruptions can lead to cognitive impairment and neurological issues.

The Unique Dependency Of Red Blood Cells On Glucose

Unlike other cells in our bodies, red blood cells lack mitochondria. This means they can't use anything but glucose as an energy source.

Liver's Requirement For Glycogen Metabolism

Your liver is critical for keeping your body's energy levels steady by storing and supplying glucose when necessary.

It can uniquely convert stored glycogen back into glucose during fasting or intense exercise when blood sugar levels drop significantly. This process is known as glycogenesis.

Glucose As A Primary Brain And Kidney Fuel

Certain parts of the brain and kidneys also rely heavily on glucose for proper functioning. According to Harvard University studies, around 20% of the total daily calories consumed go towards fueling these organs.

Eye Lens' Exclusive Use Of Sugar For Functioning

Like your red blood cells, your eye lens relies exclusively on anaerobic glycolysis (the breakdown of sugars without oxygen) for its metabolic needs. This makes it highly reliant upon a constant supply of circulating plasma sugar.

Understanding this intricate dance between different fuel sources helps us appreciate how incredibly adaptable our bodies are.

Benefits Of Being In A State Of Ketosis

If you want to enhance your mental performance or safeguard against neurological disorders, achieving a state of ketosis may be the solution.

Ketosis And Improved Cognitive Functions

Ever heard about brain fog? You know, that feeling when it's hard to focus and everything seems hazy? Well, being in a state of ketosis can help clear this up. Your body starts using ketones as fuel instead of glucose.

This results in improved memory function and increased mental clarity.

Ketogenic foods

Ketogenic Diet: An Effective Tool Against Neurodegenerative Diseases

The benefits don't stop at better cognition, either.

Research suggests following a ketogenic diet may also reduce risk factors associated with severe conditions like Alzheimer's disease and dementia. But how does it work?

Ketones provide the brain with steady energy, which helps keep things functioning smoothly even as we age. So whether you're aiming for weight loss or want to improve overall health - consider giving the keto lifestyle a try.

Plantains and Ketosis

When it comes to achieving ketosis, it's essential to consider the role of food choices, including the compatibility of plantains with a ketogenic diet. While plantains are a versatile and delicious fruit, they are not typically considered keto-friendly.

This is because plantains have a higher carbohydrate content than other low-carb fruits commonly consumed on a ketogenic diet.

The key principle of ketosis is restricting carbohydrates to encourage the body to burn fat for fuel instead of relying on glucose from carbohydrates.

As such, it is generally recommended to opt for lower-carbohydrate alternatives when following a ketogenic eating plan. While plantains may not align with strict keto guidelines, they can still be enjoyed in moderation as part of a diet.


Our bodies are adaptable and capable of utilizing various fuel sources like glucose, ketones, and fatty acids.

Ketosis is where the body primarily uses fats for energy production instead of carbohydrates. This shift in metabolic function has profound effects on our health and well-being. Fat storage isn't just an excess calorie dump and a survival mechanism between meals.

A ketogenic diet can lead to improved cognitive functions by providing alternative fuel sources like ketones, which help improve focus, memory, and overall mood while reducing risk factors associated with dementia and Alzheimer's disease, among others.

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