What Fuel is Used Exclusively by Muscles Following a Day

Question

What fuel is used exclusively by muscles following a day of starvation?
A) glycogen
B) fatty acids
C) alanine
D) glucose
E) $\beta$-hydroxybutyrate

Accepted Answer

Following a day of starvation, the body shifts to using fatty acids as the primary fuel source for muscles, as glycogen stores are depleted and the body seeks to preserve glucose for the brain and red blood cells.