What is the primary source of energy for all metabolic processes in the body?

Glucose is the primary source of energy for all metabolic processes in the body. It is a simple sugar that is rapidly utilized by cells for energy production through a process known as glycolysis and is fundamental for generating adenosine triphosphate (ATP), the energy currency of the cell. Metabolic processes rely heavily on glucose, particularly in tissues that require quick bursts of energy, such as the brain and muscles during exercise.

While proteins, fats, and amino acids can also serve as energy sources, glucose is the preferred substrate in many metabolic pathways. The body can convert fats and proteins into glucose through a series of metabolic reactions, but this is usually out of necessity when glucose availability is low. In regular circumstances, glucose is readily obtained from dietary carbohydrates and is the most accessible form of energy for immediate use by the body.