Mitochondria uses ketones (fat) to generate energy via the electron tealnser chain, not sugar.

also, mitochondria, as the key energy producer, is responsible to maintaining many of our biological functions, from catabolic to anabolic one’s. To get a better concept, it is now well eastabliahed that cells with highest energy need have the highest number of mitochondria in them; brain cells have for example the highest, which is up to 1500 mitochondria per cell. When energey production, that is mitochondrial health, is compromised, so is health and wellness. So, keeping mitochondria healthy is mandatory for health and anything, from drug to life style, that can do that is a hot commodity. 

Just as a science tidbit, we inherit out mitochondrial genes from our mothers not from both, mothers & fathers!