Metabolism is the process of converting food energy into human energy to power chemical reactions.

“fundamentally when we're talking about metabolism we're talking about how we convert food energy to human energy so we take in a astonishing 70 metric tons or so of food in our lifetime and that is potential energy it's energy from the environment that's outside of us that through our metabolic pathways gets converted to a currency of energy that can then be used to pay for essentially Every chemical reaction inside our body and the bubbling up of all of those chemical reactions is our lives”