Myth: The brain can only use glucose for fuel.
Fact: The brain can function on both ketone bodies and glucose. In a completely keto-adapted state, the brain can use up to 75% of its energy in the form of ketones.
The brain can use up to 120g of glucose during a normal carb-addiction state, but it only uses 20% of your body's total metabolism. In a keto-adapted state, you only need 25% of the total glucose usage while the other 75% can come from ketones. If you do the math, subtract 75% energy in the form of ketones from 20% of the total energy used as glucose (120g) and it would equate to about 30g of carbs a day.
The whole point of eating 30-50g of carbs on a ketogenic diet is to sustain the brain with the other 25% of energy in the form of glucose while the rests of the body loses excess bodyfat, but there are other ways to get glucose. Carbs aren't the only way. See below why.
Myth_02: You have to eat carbs to provide a steady supply of glucose to your brain.Fact: Your body is an evolutionary marvel surviving millions of years adapting to unpredictable harsh environmental variables in almost every corner of the globe. Face it, we're survivors, otherwise we'd have been in same fate as the dinosaurs, long extinct.
It can fast, it can eat fat and lose weight, and it can eat only protein and synthesize its own glucose using gluconeogenesis without ever touching carbs. Should your body not find any glucose due to weather constraints or unforeseen and unexpected circumstances, you can hunt/fish and survive on animal protein and fat until the next spring.
That's how the
Eskimos did it, before North America was invaded and their food became westernized. As a matter of fact, click on the link and read this Discovery Magazine article "
The Inuit Paradox: How can people who gorge on fat and rarely see a vegetable be healthier than we are?."