The category of biological molecule called are almost universally used as an immediate energy source for living organisms.

Carbohydrates, they are found in almost every food and are used by the body to create sugar in the blood. Carbohydrates can either be found in the form of sugars or starches, and are used primarily to provide energy for the body. Most of the energy we have is used from burning fats and carbohydrates, since the body likes to use proteins to rebuild itself.

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