What are the bodys primary and immediate source of energy

Carbohydrates are the body primary and immediate source of energy.

Explanation:

It is the best form of energy. Carbohydrates are the immediate source of the energy. The macro nutrients in our body are carbohydrates, proteins, vitamins etc, the catabolism is breaking down the process of the nutrients from the body to form the energy.

The energy from the food is coming from the three forms that are  carbohydrates, fats, and the proteins. Some of the fuels are stored in our body so that the muscles and the organs can use them as an immediate source of the energy.

that is wrong, its not thymus.