«Glycogen is a multibranched polysaccharide of glucose that serves as a form of energy storage in humans,animals,fungi, and bacteria. The polysaccharide structure represents the main storage form of glucose in the body.
Glycogen functions as one of two forms of long-term energy reserves, with the other form being triglyceride stores in adipose tissue (i.e., body fat). In humans, glycogen is made and stored primarily in the cell of the liver and skeletal muscle. In the liver, glycogen can make up from 5–6% of the organ's fresh weight and the liver of an adult weighing 70 kg can store roughly 100–120 grams of glycogen. In skeletal muscle, glycogen is found in a low concentration (1–2% of the muscle mass) and the skeletal muscle of an adult weighing 70 kg stores roughly 400 grams of glycogen. The amount of glycogen stored in the body—particularly within the muscles and liver—mostly depends on physical training, basal metabolic rate, and eating habits. Small amounts of glycogen are also found in other tissues and cell, including the kidney, red blood cell,white blood cell,[medical citation needed] and glial cell in the brain. The uterus also stores glycogen during pregnancy to nourish the embryo.