Low amounts of complex carbs increases alertness. If you want to keep alert, keeping complex carbohydrates to a minimum, or fasting / [[intermittent fasting]], is valuable. Has to do with our ancestors becoming alert and ready to hunt when food in belly gets low. Need alertness and focus to hunt and gather.

Source:

• [[lex fridman podcast - 164 - andrew huberman - sleep, dreams, creativity, the limits of the human mind_rev2]]