Exercise, a behavior that is inherently associated with energy metabolism, impacts the molecular systems important for synaptic plasticity and learning and memory. This implies that a close association must exist between these systems to ensure proper neuronal function. This review emphasizes the ability of exercise and other lifestyle implementations that modulate energy metabolism, such as diet, to impact brain function. Mechanisms believed to interface metabolism and cognition seem to play a critical role with the brain derived neurotrophic factor (BDNF) system. Behaviors concerned with activity and metabolism may have developed simultaneously and interdependently during evolution to determine the influence of exercise and diet on cognition. A look into our evolutionary past indicates that our genome remains unchanged from the times of our hunter-gatherer ancestors, whose active lifestyle predominated throughout almost 100% of humankind's existence. Consequently, the sedentary lifestyle and eating behaviors enabled by the comforts of technologic progress may be reaping "revenge" on the health of both our bodies and brains. In the 21st century we are confronted by the ever-increasing incidence of metabolic disorders in both the adult and child population. The ability of exercise and diet to impact systems that promote cell survival and plasticity may be applicable for combating the deleterious effects of disease and ageing on brain health and cognition.