What type of energy is used to digest our food?

The energy that we use to digest food comes from the foods that we ate earlier. When we consume food, we are consuming a form of chemical energy. The body breaks that down into simpler and simpler units and can then store that energy in various formats. When energy is needed by cells for various processes, the stored energy is converted into the chemical energy form called ATP.

ATP then serves as a shuttle, delivering energy to places within the cell where energy-consuming activities are taking place.

As our body mechanically and chemically digests food, it uses ATP energy to do this. The energy of ATP is contained in the bonds that exist between the three phosphates that the molecule has. When those bonds are broken, the energy is released. Some students have a hard time understanding how a broken molecule can release useful energy. A snapped rubber band is a good example. When a rubber band is stretched, it is storing up potential energy. If the rubber band stretches far enough to break, then kinetic energy of motion is released as well as sound energy. The rubber band "molecule" has been broken and energy has been released. The body will do the same thing with ATP. Phosphates will be removed to release energy that is used by cells within the digestive tract to digest food. The ATP molecule is now ADP, and the body will have to use glucose from the digested food to produce more ATP units of energy.
https://www.britannica.com/science/adenosine-triphosphate