DonM, yerba mate is a very nice alternative for those trying to wean themselves off of caffeine. Caffeine is one of xanthines in the larger trimethlxanthine family. The xanthines have a similar chemistry/structure but each has its own unique set of properties and widely varying pharmacological properties.
Others xanthines are theophylline and theobromine, mateine (found in yerba mate), guaraneine (found in guarna). There is only one effect that seems to be shared by all; smooth muscle relaxation.
Mateine, like other xanthines, stimulates the central nervous system, but is not habituating or addicting. Likewise, unlike caffeine, it induces BETTER, not worse, sleep.
It is a mild diuretic, as are many of the xanthines. It relaxes peripheral blood vessels, thereby reducing blood pressure, without the strong effect on the medulla and heart exhibited by some of the other xanthines.
It improves psychomotor performance without the typical xanthine-induced depressant after effects.
While mateine has a chemical constituency similar to caffeine, the molecular binding is different, and it is believed to IMPROVE insulin sensitivity (as does green tea). You will find it in a number of diet/thermogenic/insulin-sensitivity-enhancing formulas. Since mateine seems to enhance insulin sensitivity, I would consider it to be ANTI-lipogenic. I don't know about appetite suppression, though.
After testing, researchers have concluded that even if there were caffeine in mate, the amount would be so tiny that it would take 100 tea bags of mate in a six ounce cup of water to equal the caffeine in a six ounce serving of regular coffee.
Interesting fact I picked up along the way, but caffeine suppresses insulin sensitivity by 15%. That being the case, would anyone like to join me in a cup of yerba mate? (grin)