I haven't noticed any effects, but both green and black tea make me feel better. I attribute that to caffeine though. Exercise seems the most surefire way to increase metabolism, I have had lots of success with weightloss and I have totally disregarded what I am eating, only the calories it contains and the calories I spend, and I have noticed that exercise has a lasting effect within a few weeks on the calories I spend even while not exercising, however food of any type hasn't seemed to make an effect that I can see in numbers in my testing, but my sample size is tiny, being just me.