Question

During starvation, muscle primarily uses which fuel?

• A. Fatty acids
• B. Ketone bodies
• C. Glucose
• D. Proteins

Hint:

Muscle burns fat to spare glucose for the brain.

Answer 1

The Correct Option is A

Step 1: The metabolic logic of starvation is to protect glucose for glucose-dependent tissues and to burn stored fat everywhere else.

Step 2: Lipolysis floods the plasma with free fatty acids. Muscle, having abundant mitochondria, oxidises these fatty acids efficiently to meet its energy demand.

Step 3: Because muscle preferentially oxidises fatty acids, it stops consuming glucose, keeping circulating glucose available for the brain. This makes fatty acids the chief muscle fuel.

Step 4: Ketone use by muscle wanes as fasting deepens, glucose uptake is deliberately reduced, and proteolysis is spared to protect muscle bulk, so options b, c and d do not represent the main fuel.

\[\boxed{\text{Fatty acids}}\]