During which metabolic state are epinephrine and growth hormone most likely to activate hormone-sensitive lipase?

Epinephrine and growth hormone play crucial roles in mobilizing fatty acids from adipose tissue, particularly during periods of caloric deficit or increased energy demand. In the fasting state, the body requires additional energy because glucose levels drop and glycogen stores are depleted. During this time, hormone-sensitive lipase (HSL) is activated, leading to the breakdown of triglycerides into free fatty acids and glycerol, which can then be utilized by various tissues for energy production.

Epinephrine stimulates the release of fatty acids through a signaling pathway involving cyclic AMP, which activates protein kinase A. This ultimately enhances HSL activity, promoting lipolysis. Similarly, growth hormone also contributes to the mobilization of fatty acids by inhibiting the re-esterification of free fatty acids and stimulating HSL activity.

In contrast, during the fed state, the body is focused on storage rather than mobilization of energy stores, and insulin predominates, which downregulates lipolysis. The post-absorptive state does involve some lipolytic activity, but it is not as pronounced as in the fasting state. The restorative state suggests a recovery phase after a metabolic challenge, typically implying a return to storage rather than mobilization. Thus, the fasting state is