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Medical AI Inquiry: You were designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.
user
In a well fed state, acetyl CoA obtained from diet is least used in the synthesis of
assistant
The correct answer is  Ketone bodies (acetoacetate) synthesis is decreased in fed state, so acetyl-CoA is not used for synthesis of ketone bodies in fed state.

About other options

Fatty acid (palimitoyl CoA) synthesis is increased in fed state. Fatty acids are synthesized from acetyl-CoA.
In fed state acetyl-CoA is oxidized via TCA cycle. Acetyl-CoA condenses with oxaloacetate to form citrate.
Oxalosuccinate is an intermediate of TCA cycle.