There are four ways to be food, to be life; to eat, to be eaten, to excrete, to be excreted. Every interaction which can exist can be described absolutely in terms of eating, and of being food.
On the macroscopic scales we see the grand unifying concept of eating appear to break down into three fundamental activities: Eating, Breeding, and Migrating, known as the EBM triad. Migrating is simply eating yourself in the reverse direction of being eaten, or eating yourself in the forward direction of eating. 'Eating Yourself' is incorrect in strict terms, as the migrant looses calories to the environment, in reality, Migrating is being eaten by the environment.
The whole environment where all your intents and purposes can be placed, is known as GOD and usually corresponds to the biosphere and the atmosphere of your planet, along with all the information about your biosphere and the atmosphere. GOD is the only actor, or being, which can eat itself. All other actors are being eaten by another being or by GOD at any one time.
Not to be confused with 'I am Eating Itself', which is simply your enteric nervous system hijacking your thinking gear and introducing itself. We have two fully developed centres of consciousness within our bodies. The 'mind' is the one we think is in control (it's not) and the 'gut' is the one which really is in control (we credit it with the achievements of a dog, it's own experience of existence is that of a God).