incredible science going on with a ketone fueled brain and there's so many positive things likely emanating from that but I'm going to focus on on muscle and I'm going to start first here with um some data on keto adaptation in glycogen metabolism and showing you a graph here from uh a study we published back I believe it was 2015 uh in Elite group of ultraendurance athletes that were either following a traditional High carbohydrate or traditional low carbohydrate diet I'm not going to go through all the data in that paper but the low carb athletes were prodigious fat burners they had twice the level of fat oxidation and U performed a three-hour B of exercise using about 90% fat compared to the high carb athletes which were using more along the lines of 40 or 50% fat uh but what was actually absolutely astonishing uh to me uh was that their resting glycogen their post exercise glycogen and their recovery glycogen levels were almost exactly the same and and you're seeing the individual responses here so there's also a remarkable homogeneity in the responses here there's no real outliers um and and then this is in the context of these low carb athletes eating a very low amount of carbohydrate so quite unexpected because I think we're we're taught that to maintain optimal glycogen levels you need to be consuming a lot of exogenous carbohydrate so how how could this you know how could this happen uh so first of all if you look at the rate of glycogen breakdown and calculate that out um you know again it's nearly identical no difference at all between low carb and high carb uh in terms of glycogen utilized per unit time and if you but if you do the math here there's something quite odd um so if you kind of make a few assumptions here in terms of uh you know the uh amount of active tissue involved uh you can calculate it in actual gram amounts how much glycogen was utilized So based on these calculations about 160 grams of glycogen was depleted during exercise but we actually have indirect calorimetry data on the total amount of glucose oxidized that actually was terminally oxidized to generate ATP and that was only around 60 a little over 60 grams so the big question is what the heck happened to 100 grams of glycogen if it can't be accounted for in breath and glucose oxidation and I'm not sure I have the answer it's U it really has not been followed up on but if we take a look here um drill down a little deeper into the biochemistry so you've got glycogen break broken down into glucose and then of course glycolysis and typically if you look at the end product of glycolysis pyate u a lot of that is being converted to aceto COA through pyrovate dehydrogenase and that's the entry point into the kreb cycle for terminal oxidation and of course fatty acids can also serve as a source of acetyl COA but we know that ketogenic diets actually decrease pdh activity uh and most of the aceto COA that's being used to generate atps coming from fatty acids because you have an abundance of fatty acids when you're keto adapted so that's why I kind of have that red it out um it's unlikely a lot of pyate is going in that direction but pyate can also it has other Fates so it can be converted into oxelo acetate and this is interesting because oxelo acetate is necessary it's kind of an anapol actic substrate for the kreb cycle you need oxelo acetate uh for the CB cycle to run in fact I don't know if if it's still in the textbooks or not but you I was taught that fat Burns in the flame of carbohydrate which doesn't make a whole lot of sense um when you think about it um but the basis of that was that if you're U burning fat you have to have a source of axilo acetate and typically ailo acetate is is derived from from glucose so that's where that comes from even though it doesn't make a lot of sense but that's likely perhaps one reason why in a keto adapted State you need to have a fully functioning kreb cycle that perhaps breaking down glycogen and going through glycolysis helps keep the crab cycle running by providing a source of axillo acetate pyate could also be converted to lactate uh and that also I have that you know green because I think that likely occurs to a greater extent in these keto adapted athletes and lactate is a great you know source of carbon uh for the cell and can even be used directly as an energy source and then you also have this sort of other pathway parallel to glycolysis uh the pentos phosphate pathway and that produces some important um products as well like reducing equivalents uh and adph as well as uh five carbon sugars that are necessary for nucleotide synthesis for RNA DNA repair so there could be advantages to having a source of glucose in the keto adapted state in terms of promoting reducing power and and five carbon sugars as well so I think this is all hypothetical but all reasons why from an evolutionary perspective uh being keto adapted um you still might want to have normal glycogen levels typical glycogen levels for