I feel that apart from exercise, how much on uses their brain is bound to make a big difference given how much energy it can consume during tasks like playing c

I feel that apart from exercise, how much on uses their brain is bound to make a big difference given how much energy it can consume during tasks like playing chess or programming vs idle. Not sure to what extent this is taken into consideration in studies such as this. At least from personal experience carbs seem like the preferred fuel for the brain and its no wonder why its popular at long coding sessions and hackathons