Most people consume way more carbohydrates then they think. When performing assessments with new clients it's very common to hear people eating a breakfast like this; yogurt (28g) with perhaps a bagel (56g) and an orange juice (25g). That's over 100g of carbs in one meal!
The first place your body will use fuel is where it's conveniently located for immediate use; in the blood stream. So if you eat a breakfast like the one above and go for a workout your body will be using that sugar for energy. Anywhere from 15-20g of sugar is free flowing at once. (Your body can also do a few other things with that sugar.) But let's say you ate that sugar and did no activity or not enough activity to burn it off, your body would then store the excess sugar in a reserve tank for later use. The 2 major reserve tanks are your liver and muscles. The liver can hold anywhere from 90-120g of stored glucose (called glycogen) at once and the muscles can hold around 250-325g of glycogen depending on how much muscle you have.
Now I know what you're thinking. Your thinking that the muscle can hold a lot, right! Well, not really because glycogen compounds itself over a matter of days and it's never fully depleted. So as an example; if you consumed 300g of carbohydrates one day and did no activity and the next day you repeated that, chances are you've "splilled over" into your third tank. (unless you were gifted with great genetics and a fast metabolism)
Now what about the third tank? The third tank you won't like so much. If your body is saturated with glycogen and the body has no more room to store it in the liver and muscles the body will convert the glucose to fat and store it in your fat cells for much later use, hopefully.
Now off to Kanata to do my own workout.