Oh, I know it varies on a personal basis. I was just asking for what you, abracadabra girl (or anyone else reading this), thought.
I think teas are fine for a fast, as long as they're non-caffeinated and not drank (drunk?) for the calories (though I don't think there are calories in tea).
I think this depends on your body type. When I was a lot skinnier than I am now, I could hardly go a few hours without eating. I also became extremely anxious when I took caffeine while hungry. I tried to fast then but became extremely imbalanced and anxious. I could only fast for one day at a time, and I felt hardly any benefits.
In my current state, I can take 3 cups of coffee on an empty stomach and only get hungry. I have much more "meat" on my bones now, and have naturally shifted to a different set of food preferences.
Generally, in ayurveda and also in our local mode of healing, it is believed that "vata" people-- those who have anxiety, coldness, dryness, and a lot of "wind" in the body are not recommended for intense fasting. Incidentally, the "vata" element is also aggravated by caffeine. (These
profiles may be confusing for a lot of people, here is a basic intro. It will take a little reorientation for those steeped in Western orientation, but it is fun to see the patterns).
You can imagine how taking caffeinated drinks on a fast will spell failure for some people, and will be okay for others. Just think of how the different people you know react differently to both caffeine and being hungry.
In fact, fasting beyond two days is only recommended for certain body types, or for people with certain medical conditions.
Getting off a fast is as important as the fast itself. You need to be sure not to binge, but also to eat things that will help the process along, not negate your whole experience. In my experience, I feel best when I eat only very simple boiled vegetables, or some juices. You should also only eat when you are hungry.
Remember, a fast need not be drastic. It is sometimes as simple as skipping dinner and going to bed at 9PM! You will find that you feel great and light, and wake up without heaviness in the morning!