We consume that which is already refined. The gasoline in the tank of my car is a very potent distillation of bones, leaves, trees. The sugar in my tea had to be worked out of a sugar cane - beating it to a pulp, processing it to squeeze out the sugars. Not long ago a person was considered “refined” when they wore the most fashionable clothes and spoke with a certain accent and vocabulary.
The things that sustain us physically are abundant in nature and hidden within it. Eating refined sugar causes the body all sorts of problems because the sugar enters the bloodstream too quickly. We get an immediate high and a corresponding low, and no lasting benefit. Eating something like a vegetable requires digestion - the participation of the body in breaking down what we eat into nutrients and waste.
This is also the process of uncovering wisdom - taking information, often from various sources, and breaking it apart to find what nourishes us, leaving what doesn’t behind. Your personal yoga practice is the nourishment of your teaching. The process of practice, inquiry, digestion and deepening understanding is a radically personal one. Taking workshops from traveling teachers can be fun and energizing - much like eating refined sugar. That experience either moves through you quickly without digestion, as the teachings are the experience of another. Worse, one can end up parroting the language of another teacher without the digestive process in place at all.
The process of refinement must be ours, because it is that internal processing that creates wisdom from information.
Once we’ve done that, we become nourishment for others to do the same.