Scientists have found that drinking this healthy tea will increase the heat production of your body, also called thermogenesis. This effect was first thought to be due to the caffeine content of green tea as caffeine is known for this effect. However, the caffeine amount in this kind of tea has a bigger effect on the extra calories burned than the same amount of pure caffeine.
This suggests that there are more active ingredients in green tea, and catechins, especially EGCG (epigallocatechin gallate), are thought to work synergistically together with the caffeine. This is especially important for people who are sensitive to caffeine as tea is the lower caffeine option, so in case your are sensitive to caffeine or want to reduce it's consumption for health reasons, tea is the safer option.
