What is the chemical process of converting food into usable energy known as?

The chemical process of converting food into usable energy is known as metabolism. Metabolism encompasses all the biochemical reactions that occur within living organisms to maintain life. It includes both the breaking down of food (catabolism) to release energy and the building up of components needed for growth and repair (anabolism). Essentially, metabolism transforms the nutrients in food into energy that cells can use to perform their functions.

Digestion refers specifically to the mechanical and chemical process of breaking down food into smaller components in the gastrointestinal tract, which is a preliminary step before metabolism can occur. Absorption pertains to the process by which nutrients from digested food pass through the intestinal wall into the bloodstream to be transported and utilized by the body, but is not the same as the energy conversion process itself. Fermentation is a type of metabolism occurring in anaerobic conditions, often associated with the breakdown of carbohydrates by microorganisms, but it’s not the broad term for the overall process in humans and many other animals.

Thus, metabolism is the correct choice as it encapsulates the entire series of chemical reactions that transform food into energy.