This could be a mechanism for future intracellular repair. Build little repair robots that look like mitochondria, have them insert into cells, do their magic, then leave.
Or you could occasionally fast for 5-7 days to dramatically ramp up the intensity of autophagy/mitophagy in order to have your body do this for you. No robots needed. You may also discover that you like the way your brain and body operate with a different ketone/glucose energy balance.
Not trying to persuade you to try again, but if you ever desire to, electrolyte deficiency (particularly potassium) is a common reason that people experience headaches or cramps when fasting or starting ketogenic diets. Watch out for sugar in commercial electrolyte tablets though!