On average 300g glycogen in the whole body - I guess that number would vary with how much muscle you carry. There is another theory that a certain amount of glucose is needed to completely metabolize fatty acids for energy. This might explain why some people don't lose body fat on a high fat diet if carbs are too low. HOwever, some people, if this theory is true, manage to make enough glucose out of surplus protein to burn the fatty acids. Those would be the zero carbers who are successful. Just a theory though. Incompletely metabolized fatty acids are ketones - but ironically a lot of people don't seem to be able to lose fat on a keto-driven metabolism. Dr K's diet, because of the carbs, could be called a fat-driven metabolism, which is different. It may be easier to lose weight - especially it seems for females, on a fat driven metabolism and not a ketone-driven one. These are ideas that have been discussed on a yahoo group I'm part of.