That is not all that accurate; “muscle mass” lost during a relatively short fast (1-2 days) is due to glycogen depletion - ie. you’re burning your sugar stores, and your body sheds 3-4mL of stored water for every gram of glycogen burned.
If you stop to think about it, it’s a bit nonsensical to claim that the body would burn additional calories (that it doesn’t have) to convert existing muscle into fat, rather than just burn existing fat stores as a fall-back source of energy.
Muscle breakdown only really begins when the body starts to experience a significant shortfall in required essential amino acids over a prolonged period of time, or significant physical stress.
That is not all that accurate; “muscle mass” lost during a relatively short fast (1-2 days) is due to glycogen depletion - ie. you’re burning your sugar stores, and your body sheds 3-4mL of stored water for every gram of glycogen burned.
If you stop to think about it, it’s a bit nonsensical to claim that the body would burn additional calories (that it doesn’t have) to convert existing muscle into fat, rather than just burn existing fat stores as a fall-back source of energy.
Muscle breakdown only really begins when the body starts to experience a significant shortfall in required essential amino acids over a prolonged period of time, or significant physical stress.