The chemical that speeds up the changing of food into a usable form is enzymes.

Here's why:

* Enzymes are biological catalysts: They accelerate chemical reactions without being consumed in the process.

* Digestion is a series of chemical reactions: Food molecules are broken down into smaller, simpler molecules that our bodies can absorb and use for energy, growth, and repair.

* Enzymes are specific: Each enzyme has a specific shape that allows it to bind to a particular molecule (its substrate) and facilitate its breakdown.

For example, the enzyme amylase breaks down starch into simpler sugars, while protease breaks down proteins into amino acids.

So, enzymes are essential for digestion and the efficient conversion of food into usable energy and building blocks for our bodies.