What Happens When the Fuel Changes
Imagine your body as a car with two fuel tanks. One tank is fast and light, burning almost instantly: this is carbohydrates, glucose. The second tank is slow, dense, a reserve: this is fat. As long as you have access to the first tank, the body almost never seriously touches the second one. Why take the complicated path when there's an easy one available?
But then you remove carbohydrates. Blood glucose levels begin to drop. And here it's important to understand the main thing: the body doesn't panic, it doesn't run "out of gas." It's not designed to stop functioning just because one type of fuel is in short supply. It has a built-in backup mechanism, refined over millennia — switching to fat.
The doctor describes this in the simplest terms:
"When there's a shortage of carbohydrates, and correspondingly a shortage of glucose in the blood, the body switches to burning fat. The liver turns this into ketones, which feed the brain directly."
This is the key phrase, and it contains the whole mechanics of the process. The liver takes on the role of a processing plant. It begins breaking down fat reserves directly and producing special molecules from them — ketone bodies. This isn't some exotic process, but a standard program built into the body, which simply rarely switches on at full power, because modern people almost never give their bodies a reason to activate it: carbohydrates in one form or another are present in the diet almost constantly.
When comparing the two types of fuel, the doctor uses the image of two kinds of fuel: gasoline and diesel. These aren't the same substance, and an engine runs on them differently — it accelerates differently, pulls differently, behaves differently under load. In the same way, glucose and ketones give the body qualitatively different energy, even though the goal is the same — to supply cells with fuel.
In real life, this switch often happens unnoticed by someone who first removes sugar, bread, and grains from their diet. The first few days feel like a crash: the usual lightness is gone, and the new one hasn't appeared yet. This is a natural part of the process — the body hasn't yet ramped up its ketone production chain to full capacity, while the old energy source has already been cut off. This isn't a reason to panic, but it is a reason to approach the transition consciously, rather than as a simple "just cut the sugar and everything will work itself out."
Practical step. If you're planning to significantly reduce carbohydrates, start with observation rather than abrupt refusal. Over the course of several days, simply note — what time of day you usually eat fast carbohydrates, and what state you're in at that moment: fatigue, boredom, anxiety, habit. This will give you a map of exactly what you're changing before you change it abruptly.
Ketones — Exclusive Fuel for the Brain
One of the most important and often overlooked facts: the brain cannot feed directly on fat. A fat molecule is too large and "inconvenient" for a neuron — the brain simply doesn't have a mechanism to use it directly as fuel from the tank. And here the liver steps in — it creates an intermediate product from fat that the brain is able to accept and use. This is ketones.
The doctor calls ketones "purely and exclusively one hundred percent brain fuel" — a substance literally created to feed nervous tissue specifically when the usual glucose is in short supply. This isn't a byproduct of metabolism, but a full-fledged, specially designed high-quality energy source provided by nature.