Conjugated Linoleic Acid, or CLA, is a term used to refer to a mixture of fatty acids that have the general structure of linoleic acid (18 carbons in length, 2 double bonds) where the double bonds exist two carbons away from each other; they are all polyunsaturated fatty acids, and some may be trans fatty acids.
Although many exist, only two are commonly referred to. One called c9t11 (cis-9, trans-11) and the other t10c12 (trans-10, cis-12), named after what bond occurs where on the side chain.
CLA has been investigated to be a fat burner and health promoting agent due to its effect on a molecular signalling receptor family named PPAR which is related to fat burning, steroid signalling, inflammation, and glucose/lipid metabolism.
However, human studies on CLA are very unreliable and the overall effects seen with CLA are not overly potent as well as sometimes contradicting. CLA is a good research standard to investigated fatty acids and the PPAR system, but its usage as a supplement for personal goals is quite lacklustre.