How can you remove energy conservation mechanisms to increase brain performance? (70) - Incrium

Sid (of NY) mentioned that when he had a near death experience he was able to think ultra fast about his options for survival, at a level he couldn't normally. He also said he was more hungry afterwards.

Brains consume lots of calories. Evolutionarily, this is inconvenient. It seems likely that brains are operating at some curve of balance between energy consumption and performance.

How could you remove this inhibition and what would the effects be?