The process animals use to turn food into energy is called cellular respiration.

Here's a simplified explanation:

1. Food is broken down: Through digestion, food is broken down into smaller molecules, primarily glucose.

2. Glucose is used in cellular respiration: This process occurs within the cells, specifically in the mitochondria (often called the "powerhouse" of the cell).

3. Energy is released: During cellular respiration, glucose is broken down further, releasing energy in the form of ATP (adenosine triphosphate).

4. ATP is the usable energy: Cells use this ATP to fuel all their activities, such as muscle contraction, nerve impulses, and building new molecules.

Let me know if you'd like a more detailed explanation of cellular respiration!