Here is a bit of info on CLA. Keep in mind that in order for CLA to be effective, moderate to high doses must be used. The reason for this is that CLA is preferentially oxidized for fuel, rather than stored peripherally.
CLA is a naturally occurring fatty acid found primarily in beef and dairy fats. The reason that it is found primarily in beef and dairy products is because CLA is formed from linoleic acid by bacteria in the gut of cows (or herbavors). The cows then absorb the CLA and it becomes incorporated into lipids in the cows, including milk lipids.
How does it work?
CLA increases fat oxidation.
(West, D. B., J. P. DeLany, P. M. Camet, F. Blohm, A. A. Truett, and J. A. Scimeca. Effects of conjugated linoleic acid on body fat and energy metabolism in the mouse. Am. J. Physiol. 275 (Regulatory Integrative Comp. Physiol. 44): R667-R672, 1998)
CLA has been shown to increase certain enzymes responsible for fatty acid beta-oxidation. This means that the body’s ability to burn fat goes up significantly with CLA supplementation.
Inhibition of triglyceride uptake into fat cells.
(Park, Y., K. J. Albright, W. Liu, J. M. Storkson, M. E. Cook, and M. W. Pariza. Effect of conjugated linoleic acid on body composition in mice. Lipids 32: 853-858, 1997)
The best way to get fat is to send the fat you eat straight to the fat cell to be stored. This is generally what happens when we eat fat, however CLA supplementation has been shown to decrease the enzyme necessary for fat cells to take up fat and triglycerides from the blood. This fat is then more apt to be taken up by muscle tissue where it can be burned for fuel. In fact, CLA also increases the muscles ability to burn fat as fuel as mentioned previously.
CLA increases insulin sensitivity
(Houseknecht, K. L., J. P. Vanden Heuvel, S. Y. Moya-Camarena, C. P. Portocarrero, L. W. Peck, K. P. Nickel, and M. A. Belury. Dietary conjugated linoleic acid normalizes impaired glucose tolerance in the Zucker diabetic fatty fa/fa rat. Biochem. Biophys. Res. Commun. 244: 678-682, 1998)
The reason CLA has been labeled a “partitioning agent” is because of its ability to shift the flow of nutrients away from fat tissue and towards muscle tissue. So you are starving the fat and feeding your muscle, the end result being an increase or maintenance of muscle and a reduction in fat.
CLA acts to reduce body fat stores by chronically increasing metabolic rate.
(West DB, Blohm FY, Truett AA, DeLany JP. Conjugated linoleic acid persistently increases total energy expenditure in AKR/J mice without increasing uncoupling protein gene expression. J Nutr. 2000 Oct;130(10):2471-7.)
Treatment with CLA chronically increases basal metabolic rate. Over time this elevation leads to significant reductions in fat mass. The exact mechanism by which CLA raises energy expenditure has yet to be elucidated but could act through PPARs.