Muscle Loss

The muscle contains a larger amount of available energy. During fasting, muscle proteins are used as energy-rich substrates for the first 2 days; from day 2–3 onwards, fat is primarily used. It is therefore a positively selected program for providing energy in a state of hunger. In chronic inflammations, this program is used again, and cytokines are significantly involved in muscle breakdown. Furthermore, endogenous androgen loss and immobility promote muscle loss. In aging humans, there is also muscle loss, which can be explained by immobility, androgen loss, loss of growth hormone, and loss of appetite with malnutrition. Muscle loss in old age is associated with subsequent problems such as frailty, increasing immobility, bone fractures, bedriddenness, lower quality of life, and higher mortality.