Asides from our TCM Mushroom Elixirs (Chaga + Reishi), all of our teas are calorie free and will not break your fast. In other words, you can consume them during your fasting window safely, which is one of their best qualities for supporting fasting goals. Our fasting teas especially are helpful here since they are designed for satiety, but our non-fasting, "fasting friendly" teas are still safe to consume during your fasting window. Macronutrients, or those with calories (i.e. protein, carbs, fats) will break your fast, but there is a grey area when it comes to supplements and medications to be wary about for your own personal health needs. Since it's really tricky sometimes to find out what does and doesn't, I would recommend for the best way to find out about which ones could break your fast to look them up individually and see what the internet says. I would also check out our blog for extra insight, The Flow, on these topics, especially our post here: The Beginner's Guide To Intermittent Fasting.