In this third podcast in the Bioenergetics and Brain Health series I talk about how intermittent exercise and fasting affect brain function, neuroplasticity, and resilience. Research has shown that both of these bioenergetic challenges can enhance learning and memory, improve mood, counteract aging, and protect neurons against injury and disease. I provide an overview of evidence that over periods of weeks and months cycling between challenge (exercise and fasting) and recovery (resting, eating, sleeping) periods stimulates the formation of new synaptic connections between neurons, increases neurogenesis, and bolsters neuronal stress resistance. These adaptations of brain cells to bioenergetic challenges are mediated by hormonal factors released from peripheral organs including ketones, and by changes in gene expression in brain cells. A better understanding of how bioenergetic challenges affect the brain provides a rationale for incorporating exercise and fasting into lifestyles and is also revealing new approaches for pharmacological interventions in neurological disorders.