Scientific evidence shows that physical exercise helps you build a brain that not only resists shrinkage, but increases cognitive abilities.
Exercise encourages your brain to work at optimum capacity by causing neurogenesis (production of new brain cells), strengthening their interconnections, and protecting them from damage. During exercise, nerve cells release proteins known as neurotrophic factors, such as brain-derived neurotrophic factor or BDNF, which activates brain stem cells to convert into new neurons. BDNF also triggers numerous other chemicals that promote neural health.
BDNF also expresses itself in the neuromuscular system where it protects motor neurons from degradation. BDNF’s activity in both the muscles and the brain appear to be a major part of the explanation for why a physical workout can have such a beneficial impact on brain tissue. It helps prevent, and even reverse, brain decay as much as it prevents and reverses age-related muscle decay.
Exercise also lowers the activity of bone-morphogenetic protein or BMP, which slows the production of new brain cells, while simultaneously increasing Noggin, a brain protein that acts as a BMP antagonist. The more Noggin present in your brain, the less BMP activity there is, and the more stem cell divisions and neurogenesis takes place.
Sugar suppresses BDNF, which helps explain why a low-sugar diet in combination with regular exercise is so effective for protecting memory and staving off depression.
Source: Genes, Brain and Behavior April 2011;10(3):345-53