I was prescribed green tea by my dietitian for weight loss. I tried it but I then switched to earl grey (with bergamot) black tea. I just wanted to know is earl grey also helpful in mobilizing excess fat and weight reduction? What about chamomile? Moreover, how many cups a day should I take for the weight loss effect to be substantial?
So with everything related with diet there are two effects: whether a particularly diet affects what macronutrients you eat, and the effect of the food itself.
According to NHS advice green tea in the amounts that you would consume by drinking it have limited effects on the metabolism. Missing from this advice is the evidence that in larger doses green tea can have a modest effect on energy expenditure ~5% increase in energy consumption.
I suspect that the benefits of regularly tea consumption may have more to do with behaviour than energy use though, in which case it doesn't really matter which tea you drink. To get an idea what's going on here you might like to track your calories / what you eat during the day to get a feel for the effect that that tea might be having. There can be a bit of a heisenberg effect here.
Coffee on the other hand can act as quite an effective appetite suppressant.