Final answer:
Glucose is the most readily available fuel that the body can quickly metabolize for immediate energy, which is used through glycolysis to form ATP, and any excess is stored as glycogen or fat.
Step-by-step explanation:
The readily available fuel that can be quickly metabolized for immediate energy in the body is glucose.
After eating, dietary carbohydrates are broken down into glucose, which is transported into the bloodstream.
When immediate energy is required, this blood glucose is taken up by cells and converted to energy through a process known as glycolysis, creating ATP (adenosine triphosphate), which cells use for energy.
Any excess glucose is then stored as glycogen in the liver and muscles or as fat in adipose tissue.