Deficits in cerebral glucose utilization in Alzheimer’s disease (AD) arise decades before cognitive impairment and accumulation of amyloid plaques and neurofibrillary tangles in brain. Addressing this metabolic deficit has greater potential in treating AD than targeting later disease processes – an approach that has failed consistently in the clinic. Cerebral glucose utilization requires numerous enzymes, many of which have been shown to decline in AD. Perhaps the most important is pyruvate dehydrogenase (PDH), which links glycolysis with the Krebs cycle and aerobic metabolism, and whose activity is greatly suppressed in AD. The unique metabolism of ketone bodies allows them to bypass the block at pyruvate dehydrogenase and restore brain metabolism. Recent studies in mouse genetic models of AD and in a human Alzheimer’s patient showed the potential of ketones in maintaining brain energetics and function. Oral ketone bodies might be a promising avenue for treatment of Alzheimer’s disease.