The other day I was watching TV and saw an advertisement for One a Day Weight Smart Vitamins. Most of the diet plans that I've seen lately recommend augmenting your diet with vitamin supplements, something that I've done only irregularly through my year and a half attempt to reduce my weight. Since I was out of vitamins, I trudged down to Long's and picked up a bottle. The selling point of this particular brand is that it contains EGCG (green tea extract) which they claim enhances your metabolism, and doses of chromium, selenium and B vitamins. I was curious about EGCG's effects on the body. Studies have shown that consumption of green tea can have lots of good health benefits, including effects on inhibiting the growth of certain cancer tumors and possibly effects on luekemia. But I found it relatively hard to find data on the effects on diet and metabolism. The best link I found was:
Despite its many beneficial effects, I know of no good evidence to suggest that EGCG promotes weight loss. A study at the University of Chicago did show that rats injected with EGCG lost their appetites and ate up to 60 percent less than normal, but there was no effect on the rats' appetites when they were given EGCG orally. The researchers who conducted the study speculated that long-term oral administration of EGCG might have the same effect on appetite as the injections but cautioned that humans would have to drink green tea constantly to get the results seen in the animal study. Furthermore, the EGCG injections caused hormonal changes in the rats that could have negative effects on health if they occurred in humans.
In other words, pretty speculative effects for weight loss. Dr. Weil does recommend drinking green tea, which (because you are consuming multiple cups of a liquid) probably does help you eat less, and has other proven health benefits.
Finding good information about diet is still really difficult.