Stanton D. answered 03/07/21
Hi Chichi O.,
The body brings the ATP and the starting other reactant together enzymatically so that as the ATP hydrolyses a phosphate off, the energy is used to lever the reactant to product.
Then you make more ATP.
Incidentally, your body uses at least 6 distinct types/locations of molecules as energy storage. Do you know them all?
--Cheers, --Mr. d.