Low carb, or starvation metabolism, is the 'normal' metabolism. Low carb intake, or starvation, presents the opposite challenge than what we neolithic humans usually face (how to dispose of excess blood sugar before it damages our nervous system), in that it has to generate enough glucose to feed glucose dependent tissues (primarily, the brain!).
A quote from the article: "the metabolism of carb restriction = the metabolism of starvation. I would maintain, however, based on my study of the Paleolithic diet, that starvation and carb restriction are simply the polar ends of a continuum, and that carb restriction was the norm for most of our existence as upright walking beings on this planet, making the metabolism of what biochemistry textbook authors call starvation the ‘normal’ metabolism."
Where does the body come up with glucose when you are either starving or restricting carb intake? First, from muscle tissue, protein from which is broken down in the liver to create glucose. However, this isn't an ideal solution for the long term, for the obvious reason that you'll live better with more muscle, especially if you need to hunt and kill some food. So keeping mind, as Dr. Eades reports that "normal blood sugar represents only about a teaspoon of sugar dissolved in the entire blood volume", you might assume that an "average person requires about 200 grams of sugar per day to meet all the needs of the glucose-dependent tissues". So, how can a starving human spare glucose? Easy, ketones, which are a fabulous glucose substitute, and are a by product of the break down of fats in the liver which is part of gluconeogenesis. That's right - the machine is so incredibly efficient that it converts protein to sugar, a process powered by the body's really big energy storage tissue, fat, the by product of which (ketones) reduces the amount of gluconeogenesis required.
"Although ketones can’t totally replace all the sugar required by the brain, they can replace a pretty good chunk of it. By reducing the body’s need for sugar, less protein is required, allowing the muscle mass (the protein reservoir) to last a lot longer before it is depleted. And ketones are the preferred fuel for the heart, making that organ operate at about 28 percent greater efficiency."
As the Dr. says, "Fat is the perfect fuel." This process is beautiful, man, just beautiful. At least, it is if you are a *geek like me.*
Dr. Eades again: "If, instead of starving, you’re following a low-carb diet, it gets even better. The protein you eat is converted to glucose instead of the protein in your muscles. If you keep the carbs low enough so that the liver still has to make some sugar, then you will be in fat-burning mode while maintaining your muscle mass, the best of all worlds. How low is low enough? Well, when the ketosis process is humming along nicely and the brain and other tissues have converted to ketones for fuel, the requirement for glucose drops to about 120-130 gm per day. If you keep your carbs below that at, say, 60 grams per day, you’re liver will have to produce at least 60-70 grams of glucose to make up the deficit, so you will generate ketones that entire time."
In the mean time, while you are making your own sugar and ketones from stored fat and ingested fat and protein, your body's systems are not fully engaged transforming and packing excess sugars into fat cells. When not tied down by that emergency, your body will clean up AGEs (advanced glycation end products), amyloid plaques and such, while sustaining a low blood sugar level, meaning these things are not regenerated in as great a volume.
Low blood sugar, fewer AGEs and decreased amyloid plaques is likely an all win scenario - unless you would like the challenge of rapid aging with atherosclerotic disease, loss of internal tissue pliability, loss of memory and cognition, and the other not-so-delicious results of metabolic syndrome.
Edited 10 March, 2011
Edited 10 March, 2011
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