What can be defined as the overall process of breaking down food for energy?

The overall process of breaking down food for energy is known as digestion. This complex process involves several stages, beginning in the mouth with mechanical breakdown and enzymatic action on food, and continuing in the stomach and intestines, where further chemical breakdown occurs. As food is digested, nutrients are released and absorbed into the bloodstream, providing the energy required for the body's various functions.

Ingestion refers to the act of taking food into the body, while defecation is the process of expelling waste materials. Excretion involves the elimination of waste products from the body but does not pertain to the breakdown of food. Therefore, digestion encompasses all these processes as it specifically focuses on converting food into energy through chemical and mechanical means.