Carbohydrate Guide
What is glycogen?
Every gram of carbohydrate you eat and don't use immediately gets bundled into glycogen — your body's rechargeable energy battery.
How it works
After digestion, carbohydrates become glucose in your bloodstream. Glucose not needed right away is linked together into a branched storage molecule called glycogen and stored mainly in two places: your muscles (used locally by that muscle during activity) and your liver (which can release glucose back into the bloodstream to keep blood sugar stable, including fueling your brain between meals).
Combined muscle and liver glycogen typically stores somewhere in the range of 400–500 grams of carbohydrate in an average adult, though this varies with body size, muscle mass, and training status.
Depletion and refilling
During prolonged or intense exercise, glycogen stores gradually empty, which is a major contributor to fatigue and declining performance late in a workout or endurance event.[1] Refilling glycogen happens through eating carbohydrates — athletes with heavy training schedules sometimes deliberately "carb load" before long events to maximize stores. See our carb loading guide for the details.
Keep reading: What carbohydrates actually do · Carb loading for athletes · How many carbs per day