Catalyzes the initial step in triglyceride hydrolysis in adipocyte and non-adipocyte lipid droplets (By similarity). Component of a feedback loop involving atfs-1, atgl-1 and hlh-11 (PubMed:33078707). Promotes fat oxidation in response to mitochondrial stress (PubMed:33078707). May play a role in the response of the organism to starvation, enhancing hydrolysis of triglycerides and providing free fatty acids to other tissues to be oxidized in situations of energy depletion (PubMed:19052547, PubMed:20176933, PubMed:24120942, PubMed:25202121, PubMed:26083785, PubMed:26098762). Acts coordinately with lid-1 within the lipolytic cascade to distribute stored energy to tissues (PubMed:25202121). Together with lipid droplet protein cgi-58, regulates lipid reserves as well as lipid droplet size and localization during the dauer phase in response to phosphorylation by ampk (PubMed:19052547, PubMed:26083785, PubMed:26098762). May regulate serotonin-mediated lipolysis in metabolic tissues (PubMed:24120942). a triacylglycerol + H2O = a diacylglycerol + a fatty acid + H(+) Glycerolipid metabolism; triacylglycerol degradation. Interacts with par-5 (PubMed:26098762). Interacts with lid-1 (PubMed:25202121). Interacts with cgi-58 (PubMed:26083785). Accumulates in the cytoplasm when phosphorylated and within lipid droplets when unphosphorylated during the dauer phase (PubMed:26098762). Localization on lipid droplets enhanced by interaction with cgi-58 (PubMed:26083785). Expressed in the hypodermis (PubMed:19052547, PubMed:26098762). Expressed in the intestine (at protein level) (PubMed:24120942, PubMed:33078707). May be induced by serotonin. Phosphorylation at Ser-303 by aak-2 results in possible instability and cytoplasmic accumulation during the dauer phase. Ubiquitinated (PubMed:25202121, PubMed:26098762). Ubiquitination may decrease upon phosphorylation by kin-1 (PubMed:25202121). RNAi-mediated knockdown reduces stored lipid droplet hydrolysis during fasting resulting in retained/increased lipid droplets and there are also increased lipid droplets in the fed state (PubMed:24120942, PubMed:25202121). Suppresses fasting-induced oxygen consumption (PubMed:25202121). RNAi-mediated knockdown abrogates the increased fat loss and increased oxygen consumption rate observed in the hlh-11 ok2944 mutant (PubMed:33078707). RNAi-mediated knockdown also abrogates the increased fat loss observed following overexpression of flp-7 (PubMed:28128367, PubMed:33078707). Furthermore, RNAi-mediated knockdown reduces the induction of hsp-60, an indicator of mitochondrial stress following overexpression of either flp-7 or hlh-11 (PubMed:33078707). RNAi-mediated knockdown in aak-2 mutants improves the survival of dauer larvae (PubMed:19052547). RNAi-mediated knockdown in daf-2 constitutive dauer phase mutants results in enlarged lipid droplets possibly due to an accumulation of unhydrolyzed triglycerides (PubMed:26098762).