I think everyone's tbi is going to affect them differently.

I know for myself, if I am hungry, then I experience an increase in symptoms - even on my best days.

I need to eat a lot of protein now in order to function as well as possible, much more than I ate before the TBI.

I would strongly caution against anyone trying to fast to help them to relieve symptoms - especially considering the desperation that most people feel to get better with PCS which may lead them to trying almost anything.