Question

explain how the energy we get from food directly comes from sun

Answer 1

Sun gives heat and light energy to earth. Plants use this energy and make food. The energy we get comes when we eat these plants. or when these plants are eaten by animals,they get the energy. they need. When we eat these animals, we get the energy which is in animals but originally was in plants.
 We also have electricity as a form of energy. It is mostly made from fossil fuels i.e. coal ,petroleum, natural gas. These fuels are formed from dead plants and animals, which had themselves used sun's energy.
Hence, we can say that sun is the source of all energy on earth