In answer to this May 16, 2007 post: "There is no way for brain cell to use ketones or modify fat for energetic purpose. Ketones are highly toxic and cause the brain tissue damage, irreversible by the way." I have found the following contradiction from my new favorite book, Good Calories, Bad Calories
by Gary Taubes.
On page 456.
Without carbohydrates in the diet....the brain and central nervous system will run on ketone bodies, converted from dietary fat and from the fatty acids released by the adipose tissue; on glycerol, also released from the fat tissue with the breakdown of triglycerides into free fatty acids; and on glucose, converted from the protein in the diet.
Further on page 456.
A good discussion of the rationale for a minimal amount of carbohydrates in the diet can be found in the 2002 Institute of Medicine (IOM) report, Dietary Reference Intakes. The IOM sets an "estimated average requirement" of a hundred grams of carbohydrates a day for adults, so that the brain can run exclusively on glucose, "without having to rely on a partial replacement of glucose by ketone bodies." It then sets the "recommended dietary allowance" at 130 grams to allow margin for error. But the IOM report also acknowledges that the brain will be fine without these carbohydrates, because it runs perfectly well on ketone bodies, glycerol, and the protein-derived glucose.
Although I have not consulted the original source cited, the 2002 Institute of Medicine report, I trust that the author has. I have found this idea that the brain runs "perfectly" on ketones in a couple reliable sources and tend to believe it.
So I have redoubled my effort to remove carbs from my diet more completely in an attempt to reduce my insulin level.