A

Isoleucine is catabolized to both acetyl-CoA (a ketogenic precursor) and propionyl-CoA → succinyl-CoA (a glucogenic precursor), so it is classified as both ketogenic and glucogenic. Leucine is exclusively ketogenic, whereas arginine and glycine are purely glucogenic [Doi et al., 2007, PMID 17299083; Yu et al., 2021, PMID 33887198].