Introduction to energy storage in the human body

Energy in the human body is mainly stored in two storage substances - triacylglycerols (TAG) and glycogen. TAGs are more convenient for storage. The complete oxidation of 1 g of TAG yields approximately 38 kJ (9 kcal), from 1 g of carbohydrates or proteins only 17 kJ (4.1 kcal). During starvation, some plasma proteins (e.g. albumin ) and also muscle proteins are broken down first.

The energy reserve of a man with an average weight of 70 kg at the beginning of starvation is:

1. 400,000 kJ in TAG (about 10.5 kg, about 15% of body weight)
2. 100,000 kJ in proteins (muscles)
3. 8,000 kJ in glycogen (2,500 kJ in liver glycogen and more than twice that in muscle glycogen)
4. 170 kJ in glucose

If we calculate that our body consumes approximately 2,000 kcal daily, the reserves of liver glycogen and glucose would be enough for one day at most. But TAG can cover these claims for a period of weeks.