What SHOULD You Drink During Fasting: ACCEPTABLE LIQUIDS – Dr. Berg

Water is the best drink that you can take during intermittent fasting to keep you hydrated. It is completely calorie-free, so it will not break your fast. Some signs[1] that you are not getting enough water during your intermittent fast include headaches, muscle cramps, dizziness, and fatigue. 
Water serves as a source of some micronutrients such as magnesium. Sadly, during the purification process, some bottled water brands remove some of the minerals. This type of water known as demineralized water[2] will not be giving you those essential minerals that you need. Consider choosing water brands that do not remove the natural minerals present in water or brands that replace the minerals after purification. 
Mineral Water ea offers numerous health benefits[7], and it is an excellent beverage for your fasting hours. A refreshing cup of tea can help you relax and feel better[8]. It does not matter the type of tea you are taking for intermittent fasting, so black, green, and herbal teas are all great. They are typically calorie-free, so they will not negatively affect your fast. However, do not add cream, sugar, or artificial sweeteners to your tea if you want them to remain zero-calorie.  
Green tea may help with hunger pangs. It offers other benefits[9] such as reduction in blood sugar levels, improved fat burning, cardioprotective properties, and improved metabolism. Herbal teas confer the benefits of the herb used in making them. You may also experience better gut health[10] by taking teas. 
https://www.tnhealth.org/nutrition/what-you-drink-during-intermittent-fasting