Under which metabolic circumstance would amino acids be routed toward gluconeogenesis rather than toward new protein synthesis?

• A. Whenever dietary fat intake is above average, because high fat intake prevents any amino acid from being used in anabolic pathways including glucose production.
• B. Immediately after a high-protein meal when insulin and amino acid availability drive exclusive and complete conversion of amino acids into lipid storage rather than glucose or proteins.
• C. During the first 5 minutes after consuming a carbohydrate-rich snack when gluconeogenesis is maximized to clear excess blood glucose.
• D. During prolonged fasting or very low carbohydrate intake, when maintaining blood glucose becomes necessary and amino acids are used as substrates for glucose production.

Answer: (D)