You need enough energy to reach the finish line. Eat was is necessary, but make sure you understand which foods give more energy and which ones help rebuild cells to succeed in this marathon.
There is no good or bad food; for example, fats give energy and can be stored in case we need them afterwards, although in excess they can be over stored. Carbohydrates, if not used, also end up in the warehouse. It all depends on your activities and needs, in this game you will visit your intestines to find out.