Topics:
Animal Physiology, Animal Refresher
Sequence of Fuel Utilization During Starvation
During starvation, the correct sequence of fuel utilization is:
- Glycogen → Fatty acids → Ketone → Protein — Correct Answer
- Glycogen → Protein → Fatty acids → Ketone
- Creatine-PO₄ → Glycogen → Protein → Fatty acids → Ketone
- Creatine-PO₄ → Fatty acids → Glycogen → Protein
Explanation:
Correct Answer: Glycogen → Fatty acids → Ketone → Protein
During starvation, the body utilizes fuels in a specific metabolic priority order to preserve vital functions as long as possible:
Starvation Fuel Utilization Sequence
- Glycogen (hours): Immediate glycogen reserves in liver (~100g) and muscle (~400g) are mobilized to maintain blood glucose.
- Fatty acids (days to weeks): Once glycogen depletes, adipose tissue lipase is activated; triglycerides → free fatty acids → β-oxidation in mitochondria → acetyl-CoA → Krebs cycle + ATP.
- Ketone bodies (days to weeks): Excess acetyl-CoA in liver is converted to ketone bodies (acetoacetate, β-hydroxybutyrate, acetone). The brain and heart adapt to use ketones as fuel when glucose is scarce.
- Protein (weeks — last resort): Muscle protein is catabolized to amino acids → gluconeogenesis in liver → glucose for the brain. This stage indicates severe muscle wasting and is fatal if prolonged.
Why Other Options Are Wrong
- Options including Creatine-PO₄ → Creatine phosphate is relevant only for explosive exercise energy, not starvation metabolism.
- Protein before Fatty acids → Wrong; the body always preserves protein (muscle) as long as fat stores are available.
📚 About this Topic — Animal Physiology
This multiple choice question is from Animal Physiology, Animal Refresher. It has 4 options with a detailed explanation of the correct answer. Practice more MCQs from Animal Physiology to strengthen your preparation.
