The function of HCAR3 (hydroxycarboxylic acid receptor 3, ENSG00000255398) is as follows. G protein-coupled receptor for 3-hydroxyoctanoate, a fatty acid beta-oxidation intermediate. Signals through the inhibitory G(i)/o family of G proteins (PubMed:19561068, PubMed:37736747, PubMed:39427321). Acts as a negative feedback regulator of adipocyte lipolysis, helping to counterbalance prolipolytic signals during physiological or pathological elevations in beta-oxidation (PubMed:19561068). Acts as a low affinity receptor for nicotinic acid. This pharmacological effect requires nicotinic acid doses that are much higher than those provided by a normal diet (PubMed:12522134). {ECO:0000269|PubMed:12522134, ECO:0000269|PubMed:19561068, ECO:0000269|PubMed:37736747, ECO:0000269|PubMed:39427321}.