Provided are alternative sources of ketone bodies for reducing or eliminating symptoms of Parkinson's disease, amyotrophic lateral sclerosis (ALS, also called Lou Gehrig's disease), Alzheimer's disease, Huntington's disease, epilepsy and other diseases or disorders characterized by impaired glucose metabolism. The alternative sources of ketone bodies include mono-, di- and triglyceride esters of acetoacetate and mixtures thereof, and/or mono-, di- and triglyceride esters of 3-hydroxybutyrate and mixtures thereof. These glyceride esters can be administered orally as a dietary supplement or in a nutritional composition.