Here's a breakdown:

* Decomposition of food: This is known as catabolism. It involves breaking down complex food molecules into simpler ones, releasing energy in the process. This energy is often stored in the form of ATP (adenosine triphosphate).

* Synthesis of energy tissue: This is known as anabolism. It involves using the energy released from catabolism to build complex molecules, such as proteins, carbohydrates, lipids, and nucleic acids, which are essential for growth, repair, and other vital functions.

So, metabolism encompasses both catabolism and anabolism, working together to maintain the life of an organism.