In the episode discussing George St-Pierre's diet, it is mentioned that the ketogenic diet is medically relevant and particularly effective in treating conditions like epilepsy, due to its impact on brain metabolism. Specifically, the ketogenic diet shifts brain metabolism to predominantly ketone utilization rather than glucose. This alteration in metabolism increases the transmission of GABA (gamma-aminobutyric acid), an inhibitory neurotransmitter that reduces the electrical activity of neurons.
While this was not directly connected to George St-Pierre in the clip, it explains the potential neurological benefits of a ketogenic diet, which might relate to why an athlete like St-Pierre chooses to adhere to this type of diet year-round 1.