Glucose Can Be Formed from Muscle Protein
The body can also use proteins as a source of nutrition. After all, it is from them that glucose is formed when necessary. Imagine: glycogen reserves have been depleted, and sugar still does not enter the blood from the outside. What should the brain eat? So the body begins to convert muscle proteins into glucose, and fats help it, providing this process with energy. But proteins are also expensive fuel. After all, first of all, they serve as building material for the formation and renewal of cells, as well as for the production of antibodies. Some of the proteins are essential participants in biochemical processes. The bulk of the protein mass is contained in the muscles.
The state of the body, when the amount of protein reserves decreases by 30-50%, is incompatible with life. The death of a starving person does not occur from a lack of glucose, although in these cases there is also little of it, but from depletion of protein reserves. Because, let us repeat, protein is the most important building material of cells.
In fairness, it must be said that both the components of fat and proteins are almost constantly converted into glucose, and not only during fasting or heavy physical activity. But the percentage of their participation in a, so to speak, calm, measured life is very small. It is not for nothing that such a life is conducive to completeness. Haven't you noticed?