Lipolysis

Lipolysis is the catabolic process by which triglycerides stored in adipocytes are hydrolysed into free fatty acids (FFAs) and glycerol, which are then released into the bloodstream for use as energy substrates by other tissues, particularly skeletal muscle, the liver, and the heart. The process is initiated by hormone-sensitive lipase (HSL) and adipose triglyceride lipase (ATGL), with monoacylglycerol lipase completing the final hydrolysis step. Lipolysis is stimulated by catecholamines (adrenaline, noradrenaline), growth hormone, glucagon, and natriuretic peptides, while insulin is its primary inhibitor. In metabolic peptide research, GLP-1 and GIP receptor agonists such as Tirzepatide promote lipolysis indirectly by improving insulin sensitivity and reducing hyperinsulinaemia, allowing the natural fat-mobilising hormones to function more effectively. Growth hormone secretagogues like CJC-1295 and Ipamorelin enhance lipolysis directly through GH-mediated activation of HSL in adipose tissue, contributing to favourable body composition changes observed in research settings.