You should read more carefully what Dr. Rosedale wrote in the link you supplied. Your characterization of it is entirely [sic] accurate.
I wrote that I read the articles a couple of times, and found them flabbergasting. Js290 wrote back:
The way I read it, Dr. Rosedale offered the most generalized solution. The abstraction he makes is we simply define a gradient of metabolic derangement from 0% (healthy) to 100% deranged (diabetic). His argument seems to be simply, the diet that is therapeutic for fully metabolically deranged cannot be unhealthy for the metabolically healthy.
Analogously, it's similar to most of the paleo stance on gluten grains: just because it's tolerable doesn't make it optimal.
Given that you have written about brains function on ketones, that for the same number of carbon atoms, fatty acids produce more ATP than glucose, that the body is capable of producing all the glucose it needs, Dr. Rosedale's view is by far the most generalized and better abstraction from a health perspective.
Why come up with many different models for different use cases when a single model will work? This is how evolution and natural selection does things: the best abstraction wins.I think js290 encompasses in a nutshell exactly why I find the theories so puzzling. I don't see why we should use sick people to tell us what is optimal for all people. Nor do I know the definition of "metabolically deranged" - do we mean pre-diabetic and type II diabetic? Obese? Metabolic syndrome?
I disagree with the characterization that the "derangements" are linear. My understanding of physiology is that those with healthy beta cell function can do very well with a wide variety of carbohydrate intake and it shouldn't matter that much for optimal health. We are obligated to use glucose for fuel - we have systems in place to deal with physiologic amounts of glucose. I also don't think that post-prandial glucose "spikes" are particularly abnormal or dangerous unless they are very high and last a long time. I don't think glucose or carbohydrates as a macronutrient class per se cause diabetes. Once you get past a tipping point and start taking out beta cells, hyperglycemia, insulin resistance, and increasing damage occurs, then you have fewer options, dietarily speaking. Even then, a hard core ketotic zero carber who never cheats may be in good stead, but those who cheat are now (physiologically) even more insulin resistant than they would have been if they ate enough carbs to keep them out of deep ketosis all the time… so glucose "spikes" and area under the curve for glucose and insulin would be even higher than if there were more carbs eaten on a regular basis.
In addition, since the liver will make a bunch of glucose via gluconeogenesis, I don't see much harm in eating moderate amounts of glucose so our liver doesn't need to make it, unless you are needing to stay in deep ketosis for medical reasons. Six of one, half a dozen the other.
And, of course, I think there are certain brain illnesses that could very well benefit from deep ketosis (for some of these conditions it is merely theoretical, for others there are case studies or even pilot data, for epilepsy there is a lot of data) - brain cancers, migraines, epilepsy, bipolar disorder, dementia, autism, and schizophrenia.
In general, I think it is reasonable that fasting and autophagy should be engaged in on an intermittent basis for all individuals, including heathy ones - I know that if on one particular day I personally eat high carb or low carb, I wake up the next morning in ketosis. That is a sign of metabolic flexibility, which is a positive sign of a healthy metabolism.
Well, that is my opinion. Starchy root vegetables and fruit are good sources of nutrients and in general less expensive than good quality meat, though perhaps not less expensive or easier to store than than good quality fat, calorie for calorie. The nutrients in starch tend to be somewhat different than the ones in fat. I find them pleasurable to eat, personally, and my kids certainly prefer the starch and fruit to just fat, green leafy vegetables, and meat. Perhaps they would truly want mountains of candy and chocolate and their preferences shouldn't guide our health speculations… well, that's my opinion. I simply don't think there is enough evidence to suggest that zero carb diets are optimal for everyone for longevity and health, either from an experimental perspective or from a common sense, physiologic perspective.