According to a recent study done on mice, drinking green tea might be able to help reduce the risk of obesity and their symptoms. Researchers from Ohio State University in Columbus looked at how the compounds in green tea might interact with the bacteria in the gut and hence have an effect on obesity and their symptoms.
The researchers studied male mice for 8 weeks. Half of the mice were fed a standard diet and the other half ate a high fat diet diet. Green tea extract was fed into half of each groups. After 8 weeks, mice that ate a high fat diet with green tea extract gained 20% less weight as compared to the mice that ate just the high fat diet. In addition, they also had lower levels of insulin resistance. From this study, it suggests that green tea encourages the growth of good gut bacteria. However, readers should make note that this study was done with mice and not human participants and therefore in my opinion, it cannot be conclusively said that the same effect will happen on humans. Furthermore, to reach the amount of green tea the rats were fed would require humans to drink around 10 cups of green tea a day (or take green tea supplements).
Green tea also contains caffeine (well known stimulant that aids fat burning and improve exercise performance) and antioxidants. Studies have shown that drinking green tea can increase the amount of antioxidants in your bloodstream. In particular, the antioxidants called catechins are quite high in green tea. In particular, epigallocatechin gallate (EGCG) is well known for boosting metabolism.
EGCG can help inhibit an enzyme that breaks down the hormone norepinephrine. This leads to an increase of norepinephrine and therefore promoting more fat breakdown. Combined with caffeine, this might create a synergistic effect. The fat cell breaks down more fat and therefore releases into your bloodstream for energy. EGCG is also able to interfere with oxidation and therefore it should minimise the oxidative damage in cells. These oxidative damage is known to contribute to several illnesses such as cancer. There has been studies on animals that show that EGCG has the ability to interfere with the formation of several types of cancer, however this has not been fully understood in humans.
Personally, I think matcha is the best to fully enhance the benefits as you actually consume the leaves as well!