Originally Posted by
RH Clark
What I would like to know is when glycogen stores become depleted, how much they are depleted, how fast they regenerate on sugar compared to being simply left alone.
I'm sure consuming sugar will immediately raise your blood sugar. I also know that your body will release insulin to lower it at some point. I don't know how much actual energy that may make available VS how you may just feel better for a short time by the blood sugar increase.
I am actually more concerned about the detrimental effects of the insulin it takes to lower blood sugar.
What would be the difference in someone who has entered ketosis compared to a high carb burner in replenishing glycogen from body fat compared to X amount of sugar in the carb burner? It does make a difference and they are questions worth exploring.
Partial answer:
There are three (IIRC) glycogen compartments in muscle. Only one of them is readily available to energy metabolism and gets depleted under normal circumstances. The other glycogen may serve more of a structural role and only gets consumed under extreme conditions and it’s probably not a good thing when that happens.
Fat cannot replenish glycogen. Fat is either burned directly for energy in muscle or forms ketone bodies, which are burned in muscle and other tissues. Glucose can be reconstituted from amino acids and other scavenged molecules, but not in large amounts and under conditions where that mechanism is important, much of it is consumed by brain, which needs about 30% of its energy in that form, unlike other tissues. I don’t think know for sure, but I don’t think gluconeogenesis can replete glycogen during exercise.
Glucose uptake into muscle under exercise conditions is not insulin dependent and ingested glucose is cleared very rapidly without much insulin release.