by Jeff Cyr
I will try and keep this short and simple. Any human being on planet earth can uses a mixture of ketones and glucose to fuel their brain, probably a mixture of 60/40, or 50/50. Many human beings in today`s society have a very hard time using 100% glucose to fuel their brain`s.
In today`s society of a typical SAD high processed junk carbohydrate diet we (most of us) have become very insulin and leptin resistant. Also what contributes to this insulin resistance is the presence of to many processed oils (trans fats), this throws our Omega 6- Omega 3 ratio totally out of whack. Now our bodies have become very inflamed from this SAD high carbohydrate diet and Omega 6- Omega 3 imbalance.
Our brains use 20-25% of our total resting expenditure, most of us need 600 calories worth of glucose ( carbs) to fuel our brains on a daily basis. Our brains are the main engine that drives our metabolism and also controls everything inside of our bodies.
Our liver is the only place ( storage depot) that our brain can get ready available glucose for fuel. Your liver only stores 60-100 grams of glycogen, the storage form of glucose.
Your skeletal muscles store 300-350 grams of glycogen, these glucose reserves are for the muscles only. These glycogen reserves in the muscles lack a specific enzyme ( glucose-6-phosphate) needed to allow this stored glycogen re-entry into the bloodstream as glucose.
Your brain can also get glucose from carbohydrate when you eat a meal. This is the main reason why your brain is addicted to glucose as it`s only fuel source. When you eat the typical SAD high carb diet the carbohydrates are very quickly turned into glucose instantly into your bloodstream, presto instant glucose for the brain.
This constant raising of your blood sugar levels from this high carb diet leads to the release of large amounts of the hormone insulin from your pancreas. If you are insulin sensitive you will not need that much insulin to maintain your glucose homeostasis.
Your body is designed to maintain very narrow ranges of its blood sugar levels, usually 70-110 mg/dl, this is known as glucose homeostasis. High blood sugar itself is very toxic to the body`s cells and the blood itself. (Side note here*- your body is actually designed to maintain said blood sugar levels all by itself, your body does not need dietary carbo for this purpose, gluconeogenesis in the liver and kidneys)
When your pancreas is forced to release these large amounts of insulin the first thing that happens is that the ratio between insulin and glucagon in the bloodstream ( at the current time) is thrown way over to the insulin side. The first thing that happens is that the process of lipolysis is stopped. Lipolysis is the process of the release of stored body fat from your fat cells. Your body cannot use stored body fat for energy, it just sits there in storage. Your fat cells need the proper signal to release its fat stores from storage into the form of free fatty acids and glycerol.
Once your stored triglyceride is released from your fat cells as free fatty acids the fatty acids are bound to the blood protein albumin. Your skeletal muscle and heart muscle can use these free fatty acids as direct energy, if these cells receive the proper signaling of glucagon over insulin.
Your brain cannot use these free fatty acids for direct energy because the blood protein albumin cannot cross the blood brain barrier. Your brain has a protective barrier surrounding it called the blood brain barrier (BBB).
Your brain cannot use these free fatty acids but your liver can take these free fatty acids and make ketones for the brain. If insulin levels are low enough in the blood this increases the flow of these free fatty acids from your fat cells. These excess free fatty acids are converted into ketones by the liver. Ketones are water soluble and are capable of crossing the blood brain barrier, Presto energy for the brain.
This is what a ketogenic diet does it eliminates your dependency on carbs/insulin and allows your liver to make ketones for the brain. You do not need insulin to use fat as fuel, in fact you need the very opposite, less insulin. Your cells have what are known as Glut transporters on them. These Glut transporters need the signal of insulin over glucagon to bring the glucose transporters to the cell surface to allow glucose entry into the cell to be used as energy. You won`t need these glut transporters to be activated if your burn fat as fuel instead of glucose.
If your insulin glucagon ratio in the blood ( at the current time) is correct your skeletal muscle and heart muscle will use free fatty acids for direct energy. Your liver will also be able to make ketones for the brain with these free fatty acids. Your liver will also maintain the necessary glucose that is needed to furnish your glucose dependent tissues and the amount needed for your brain via the process known as gluconeogenesis.
You have very few cells that actually need glucose. Your brain (100% if not keto-adapted), your red blood cells, the inner parts of your kidneys (renal medulla) and your retinas, everything else inside of you can be fueled by FAT.
Stop this madness of the SAD high carbohydrate diet. Adopt a ketogenic diet today and your life will change. You will go back in time, don`t take my word for it, do your own research.