Complex carbohydrates
Such as insoluble fiber. Your body will break that down first because I is much faster than other source to convert to energy. If there isn't any carbs available your body will then convert fat into energy and lastly if there is t and carbs or fat your body will then breakdown protien into energy but that is truly the last resort. Sorry for the errors in this texts I was writing very fast and my phone will not allow me to edit.