I think compound because there were no dependent/independent clauses.
The food that we eat is made up of different types of macro molecules. Energy are stored in the chemical bonds of these macro molecules in form of chemical energy. When humans consume these food, the chemical energy in the food is transferred into their systems and it is this energy that is used to carry out all the life activities. This chemical energy can be inter converted into various forms. When the body needs warmth, the chemical energy will be converted to thermal energy to produce heat.
