According to the mystic traditions of the East, all that you think you are is nothing but food. Your body is food, your mind is food, your soul is food. Beyond the soul there is certainly something which is not food. That something is known as anatta, no-self. It is utter emptiness. Buddha calls it shunya, the void. It is pure space. It contains nothing but itself; it is contentless consciousness.
While the content persists, the food persists. By "food" is meant that which is ingested from the outside. The body needs physical food; without it, it will start withering away.
This is how it survives; it contains nothing but physical food.
Your mind contains memories, thoughts, desires, jealousies, power trips, and a thousand and one things. All that is also food; on a little more subtle plane it is food. Thought is food. Hence when you have nourishing thoughts your chest expands. When you have thoughts which give you energy you feel good.