"It takes at least several weeks to fully adapt to extremely low sugar intake, such that the body can effectively burn fatty acids and ketones… Let's see what George Cahill has to say about glucose needs in a person well adapted to no carbohydrate intake… [Cahill] recently wrote a paper summarizing many of his long professional career's findings. They are the following:
"Total splanchnic glucose production [to fulfill body needs] in several weeks' starvation amounts to approximately 80 grams daily. About 10–11 grams/day come from glucose synthesis from ketone bodies, 35–40 grams from recycled lactate and pyruvate, 20 grams from fat-derived glycerol, and the remaining 15–20 grams from protein-derived amino acids, mainly alanine."
"… An approximation for clinical use is that if a diet contains over 100 grams carbohydrate, there is no ketosis (<0.1 mM). As one decreases dietary carbohydrate, ketogenesis begins...Glucose administration to fasting normals reverses starvation metabolism rapidly..." [Emphasis mine.]
Therefore, Dr. Rosedale summarizes:
"[u]nder a fully adapted, zero carbohydrate milieu, one only needs approximately 80 g (~320 cal) of glucose daily, the vast majority of which could be derived from fat and non protein sources. Only 15 to 20g need come from proteins, and likely less if one was actually eating fat that would allow for greater glycerol production and protein sparing." [Emphasis mine.]
In Dr Jaminet's reply to Dr Rosedale, he argues that although people can survive on zero glucose consumption due to ketone generation, this is not optimal. For "perfect health," one should provide the body with some dietary glucose. Dr. Jaminet acknowledges that some level of ketosis is desirable, but this can be achieved even with consumption of 100 grams carbohydrate daily if coconut oil is consumed, or transiently during the latter parts of the overnight fast.