CLA (Conjugated Linoleic Acid)
Derived from sunflower, and safflower oils. Also, naturally occurring in dairy (although only a % of what it used to be).
Not only has CLA been shown to increase muscle mass while reducing body fat, but studies done over the last 2 decades have also shown remarkable anti-catabolic, antioxidant, and immune enhancement benefits.
Very extensive research has also been done at the Life Extention Foundation, (which were one of the first to introduce the weight reduction possibilities) and the results have been amazing.
You should have no trouble finding info on CLA.
P.S. Contrary to popular belief. CLA is best taken 4g (usually 4 gel caps) first thing in the morning on an empty stomach, rather than before, or after meals - as directed on most labels.