Drinking green tea
I have seen quite a number of articles promoting drinking green tea if you want to lose weight.
From what I read, green tea has been proven to aid weight loss by speeding up the metabolism, inhibiting fat absorption and aiding glucose regulation. This is not because of the caffeine it contains, but is instead due to the high concentration of natural antioxidants called catechin polyphenols.
However, to really notice a difference, you have to be drinking three to five cups a day, or take in supplement form.