Hi margauxmorgan
I'm late answering, and someone else will probably have a much better answer for you. There's probably some science out there that says yes, and there's probably some that says no. But personally, I've never found anything that will physically *make me* lose a craving. There are things I can do to distract myself til the craving passes, and there are things I can substitute for a craving, but sadly, nothing short of hypnosis is going to make me forget about kettle chips. >droolz<
Drinking tea (green, black, white or otherwise herbal) does give me something to do instead of chasing my craving, but that's all it is for me - a substitute. Like a similar food, exercise or more water.
Which can be cool, imo - and I'm no expert! - because about half of what I think are cravings have turned out to be thirst. So that's something else that tea does, cravings-wise, but it's nothing that water can't do just as well.
What I *have* noticed with green, barley and brown rice teas is better skin (heh - I'll wake up tomorrow with a pizza-face just for writing that), better circulation, fewer headaches, less urgency to snack at my desk, and more energy throughout the day. I'm just more likely to actually drink it than water, which I'll plan for but reliably forget about. But no magical cravings lost through tea consumption here.
tl;dr - nah, afaik. It's something relatively healthy to do and it really doesn't hurt (unless a person is a nutbar about it, I'm sure). Plus, tea is endlessly fun to play with. Which, for folks who like to concoct in the kitchen, is a blessing. Happy dunking!
post edit: Ah! I see you've asked and answered the same question yourself in at least of couple of other threads.

Glad to hear you're figuring out what works and doesn't for you! See you on the boards.
(& a very late bump - AvaTea! Thanks for your insider post about that company! Very interesting.)