The researchers identified 44 different blood-based metabolites significantly increasing in abundance after 58 hours of fasting, including 30 that have never before been connected to the practice. Alongside known markers signaling the body is moving to utilizing alternative energy stores, such as butyrates and branched-chain amino acids, an interesting increase in anti-oxidant metabolites was found. It is suggested this could be an evolutionary defense against the oxidative stress put on the body during fasting.

Interestingly, three specific metabolites known to be associated with aging and longevity – leucine, isoleucine, and ophthalmic acid – all increased in levels after fasting. Prior study by the same research team revealed these specific metabolites decrease with age and are found in notably low levels in the elderly.