on November 24, 2012
at 07:57 PM
Glycogen is stored in the liver and muscle tissue. The former is pretty standard across the board for human beings as the human liver does not vary a ton in size. Muscle glycogen storage is going to be relative to the amount of muscle mass a person had.
I'm sure you will be able to find slightly different answers, but liver glycogen storage is usually around 400-600 kcals of energy, or approximately 100-150 grams of carbohydrate. As you can imagine, this doesn't take much at all to deplete and if you do a simple 8-hour fast overnight, you're going to be glycogen-depleted in the liver.
To completely drain the body of stored glycogen, the easiest way would be to go anywhere from 24-48 hours without consuming carbohydrates, limiting protein and doing some activity. All of these, depending on the amount, will vary how long it takes to deplete glycogen. With that said, it's impossible to have completely empty glycogen stores as the body will do whatever is necessary to produce glucose. This will mean some glycogen stores, even VERY low levels, constantly being present. The only time you would have zero glycogen would be if you literally wasted away and died, and even then other things would probably cause death before glycogen was at 0%.
Even if you're jogging in a fasted state after an overnight fast, total glycogen will NOT deplete with a simple jog (liver glycogen will, overall glycogen won't) unless you're chronically on a very low carbohydrate and below average protein intake. The cumulative effect of lower starting levels of stored glycogen will make your threshold to depletion less than the standard American dieter.
To finally answer your question...which will be disappointing...it depends. It all depends on what you're trying to accomplish...care to elaborate?
on November 24, 2012
at 09:50 PM
No. Jogging is by default a "low-intensity" exercise, which means that it's predominantly "fat burning" (although obviously it burns some glycogen too).
If you do enough of it you'll will deplete your glycogen stores. 2 hours is the running duration for which most "joggers" eat carbohydrates to make suret that there muscle glycogen levels do not become too depleted ("hitting the wall" or "bonking"). If you stick to a VLC diet, you can become "keto-adapted" and begin burning glycogen at an even slower rate (delaying the onset of the "bonk" and reducing your need for carbohydrate).
No-one that can run for 2 hours still calls it "jogging" so I'm guessing that "bonking" isn't going to be an issue in your case.