What must the body continually supply for energy?

The body must continually supply ATP (adenosine triphosphate) for energy, as it is the primary energy currency of the cell. ATP is crucial for various cellular processes; it provides the energy needed for muscle contraction, nerve impulse transmission, synthesis of biomolecules, and many other biochemical reactions essential for sustaining life.

While glucose is an important source of energy and undergoes metabolic processes to be converted into ATP, it is not the direct form of energy that cells utilize. Instead, glucose must first be metabolized. Similarly, proteins are essential for a range of bodily functions, including tissue repair and enzyme production, but they primarily serve as building blocks rather than direct energy sources in most metabolic situations. Vitamins, while vital for various metabolic pathways, do not provide energy themselves but act as co-factors or co-enzymes in these processes.

The continuous regeneration of ATP from metabolic substrates like glucose, fats, and proteins means that the body must constantly supply ATP to maintain energy homeostasis, making it indispensable for all energy-requiring activities.