In my post,
This immediately, and rightly, brings up the most common question—and the most common criticism—of a ketogenic diet:
"But Chris, I read that your brain needs glucose to survive. Aren't you starving your brain?"
This is one of my favorite topics because the answer is so elegant, and it perfectly illustrates the brilliance of the human body. The premise of the question is 100% correct: Yes, parts of our body must have glucose to function.
Your brain can get up to 75% of its fuel from ketones, but that other 25% requires glucose. Furthermore, your red blood cells (which have no mitochondria) and parts of your kidneys can only run on glucose.
The myth is that you must eat glucose to have glucose.
The fact is, your body is a master alchemist. When you stop supplying glucose from the outside, your liver simply manufactures the small, essential amount it needs on the inside.
This process is called Gluconeogenesis.
What is Gluconeogenesis (GNG)?
Let's break down the word. It's the scientific definition of what it does:
Gluco = Glucose (sugar)
Neo = New
Genesis = Creation
It is, quite literally, the "creation of new glucose." It's a metabolic pathway, primarily in the liver, that takes non-carbohydrate materials and converts them into the exact, specific amount of glucose the body needs to power its essential systems.
This is not a "flaw" in the ketogenic system; it's the essential, high-efficiency feature that makes it a sustainable, long-term metabolic state.
The "Factory": Where Does the Liver Get the Ingredients?
If I'm not eating any carbs, where does my liver get the raw materials to build this new glucose? It gets them from the byproducts of my clean keto, high-protein OMAD (One Meal a Day).
There are three main ingredients for GNG:
Glycerol (from my Fat Stores): This is the most brilliant part. When your body is in "fat-burning" mode (lipolysis), it unlocks your "balloon" fat cells and pulls out triglycerides. A triglyceride molecule is made of two parts: three fatty acids and one glycerol backbone.
The fatty acids are sent to the liver to be converted into ketones (your main fuel).
The glycerol backbone is sent to the liver to be used as a primary ingredient for gluconeogenesis.
Let that sink in: My body literally manufactures the glucose it needs from my own stored body fat.
Amino Acids (from my Protein): This is the single most important reason why my clean keto lifestyle is a high-protein diet, not just a "high-fat" one.
Certain amino acids (like alanine) from the protein I eat (my beef, , pork, poultry, fish, and whey shake) are shuttled to the liver, where they can be converted into glucose.
This is a crucial protective mechanism. By providing my liver with all the amino acids it needs from my one meal, I am protecting my lean muscle mass from being broken down (catabolized) to supply those same amino acids.
Lactate (from my Muscles): When I do my calisthenics or go on my 15km weekend walks, my muscles produce lactate as a byproduct. My liver can actually "recycle" this lactate back into glucose. It's an incredibly efficient, closed-loop system.
The "Big Question": Why Doesn't This Stop Ketosis?
This is the final, critical piece of the puzzle. "If my body is making sugar, why am I still in fat-burning mode? Won't that sugar spike my insulin?"
The answer is no, and the reason is the single most important concept in all of this:
Gluconeogenesis is a "Demand-Driven" process, not a "Supply-Driven" one.
Let's compare the two:
"Normal" Diet (Supply-Driven): You eat a plate of pasta. A flood of glucose (a massive supply) hits your bloodstream, which your body did not ask for. This forces a massive insulin spike to deal with the "emergency." This insulin spike shuts down all fat-burning.
"Clean Keto" (Demand-Driven): Your body is in a fasted, low-insulin state. Your red blood cells place a tiny "order" for glucose. Your brain places a small "order." Your liver, acting as the factory, fulfills only those exact orders. It releases just enough glucose to keep your blood sugar stable and power those essential parts.
There is no "flood." There is no "surplus." There is no "emergency."
The hormonal state of ketosis (very low insulin, higher glucagon) is the "governor" on the GNG engine. This hormonal signal tells the liver: "We are in fat-burning mode. You are authorized to make only the bare-minimum glucose we need for essential systems. Do not make a single drop more."
If your liver did make too much glucose, your blood sugar would rise, which would trigger insulin, which would shut down fat-burning. The system is a perfect, self-regulating feedback loop designed to prevent this. It makes just enough glucose to keep you out of danger (hypoglycemia), but not nearly enough to kick you out of ketosis.
The Takeaway
So, "doesn't my brain need glucose?" Yes, it does. And my body knows that.
It's a brilliant, self-sufficient machine. It doesn't need me to eat sugar. It has its own "secret" fuel factory, running 24/7, that takes the byproducts of fat-burning (glycerol) and the building blocks of my high-protein meal (amino acids) and manufactures the precise, essential amount of glucose it needs, all while the rest of my body runs on its main, clean, high-performance ketone engine.
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