Brain Metabolism during Fasting*

Abstract
Catheterization of cerebral vessels in three obese patients undergoing 5-6 wk of starvation demonstrated that β-hydroxybutyrate and acetoacetate replaced glucose as the predominant fuel for brain metabolism. A strikingly low respiratory quotient was also observed, suggesting a carboxylation mechanism as a means of disposing of some of the carbon of the consumed substrates.
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