Autophagy, the process of recycling cellular components, is known to be important to the benefits of calorie restriction. This makes sense: more recycling of damaged components should mean they have less of a chance to cause additional damage due to their malfunctioning. Calorie restriction is known to slow onset of neurodegenerative conditions, and this also may have something to do with autophagy: "Protein aggregates or inclusion bodies are common hallmarks of age-related neurodegenerative disorders. ... Increasing evidence, [supports] the notion that in general aggregates confer toxicity and disturb neuronal function by hampering axonal transport, synaptic integrity, transcriptional regulation, and mitochondrial function. Thus, neuroscientists in search of effective treatments to slow neural loss during neurodegeneration have long been interested in finding new ways to clear inclusion bodies. Intriguingly, two studies [indicate] that autophagy may be a built-in defense mechanism to clear the nervous system of inclusion bodies. This new finding has implications for our understanding of aging and neurodegeneration and the development of new therapies."

Link: http://www.ncbi.nlm.nih.gov/pubmed/19305790