A single act of giving has a value beyond what we can imagine. So much of the spiritual path is expressed and realized in giving: love, compassion, sympathetic joy, equanimity; letting go of grasping, aversion, and delusion. To give is powerful. That is why the Buddha said that if we knew as he did, the power of giving, we would not let a single meal pass without sharing some of it.
Sharing food is a metaphor for all giving. When we offer someone food, we are not just giving that person something to eat; we are giving far more. We give strength, health, beauty, clarity of mind, and even life, because none of those things would be possible without food. So when we feed another, this is what we are offering: the substance of life itself.