The long form is expressed in steroidogenic tissues such as testis, where it converts cholesteryl esters to free cholesterol for steroid hormone production.

The short form is expressed in adipose tissue, among others, where it hydrolyzes stored triglycerides to free fatty acids.

[8] During fasting-state the increased free fatty acid secretion by adipocyte cells was attributed to the hormone epinephrine, hence the name "hormone-sensitive lipase".

Such enzymatic action plays a key role in providing major source of energy for most cells.

[14][15] HSL is activated when the body needs to mobilize energy stores, and so responds positively to catecholamines and ACTH.