It will break a fast for gut rest and will slow autophagy but should be ok for weightloss. I tend to feel intense hunger when I drink it but that’s me. Honestly, you would be better off using plain seltzer, I have a Soda Stream, and flavor drops like Stur or Sweetleaf that are sweetened with Stevia which will not break a fast. There is a soda brand called Zevia that has lots of flavors. Herbal tea and coffee are also allowed. Don’t forget about pickle juice! It’s a great source of electrolytes and can give you that pep when you feel weak.
It depends on your personal health, as the main issue is the insulin spike associated. You can check how much of an impact it is having with a glucose monitor. Drink one in the morning, check your blood sugar right after and then at 45 and 90 minutes. If it’s moving more than 20%, you should toss it because you have the discipline to do 21 days without food.
wouldn’t it be better to drink herb teas during a fast, or tisanes, if one uses that word instead? which of those would people here recommend? if stevia really isn’t a concern then sweetening them with that would be easy to manage, to drink hot or iced.