Branched fatty acid esters of hydroxy fatty acids (FAHFAs) are recently discovered lipids that play a role in the bodys response to fasting and high-fat diets, with a link to insulin sensitivity. These compounds consist of a long-chain fatty acid (such as palmitoleic, palmitic, oleic, or stearic acid) bonded to a hydroxy fatty acid, both ranging in length from C-16 to C-18. Specifically, 12-OAHSA is a type of FAHFA where oleic acid is attached to the 12th carbon of hydroxy stearic acid. Within the FAHFA family, OAHSAs are particularly notable for their high concentration in the serum of AG4OX mice, a strain engineered to express the Glut4 glucose transporter predominantly in their adipose tissue, which demonstrates an enhanced glucose tolerance.