What is the order of storage compounds utilized by the body when food intake is absent?

The order of storage compounds utilized by the body during periods of food intake absence is primarily driven by the availability of these compounds and the body’s energy needs. Initially, the body uses glycogen, which is a readily accessible form of energy stored in the liver and muscles. Glycogen can be quickly broken down into glucose for immediate energy needs, making it the first source the body taps into when food is not being consumed.

Once glycogen stores are depleted, which typically happens within 24 to 48 hours of fasting or intense exercise, the body turns to fat stores. Fats are broken down into fatty acids and glycerol, which can then be used as an energy source through a process called lipolysis. This allows the body to sustain itself for a longer duration since fat stores are generally more abundant than glycogen reserves.

Only after glycogen and fat stores have been significantly used does the body begin to utilize protein for energy. Proteins are usually preserved for tissue repair and various metabolic functions, but in extended fasting or starvation, the body can break down proteins into amino acids, which can then be converted into glucose through gluconeogenesis.

Consequently, the correct sequence of energy sources utilized is glycogen first, followed by fat, and