While fasting, you can drink several beverages that do not break your fast or significantly impact insulin levels. The best options include:

• Water : Plain still or sparkling water is ideal and essential for hydration during fasting

• Black coffee : Unsweetened and without milk or cream, black coffee provides a caffeine boost without calories and is widely accepted during fasting

• Unsweetened tea : Green, black, or herbal teas without any added sugar, milk, or cream are allowed and can provide antioxidants and mild caffeine (except herbal teas which are usually caffeine-free)

• Zero-calorie drinks : Sparkling water, lemon water (without added sugar), and sugar-free electrolyte drinks are generally okay

You should avoid any drinks containing calories such as regular soda, juices, milk teas, or sweetened beverages, as these break the fast

. For medical fasting (e.g., before blood tests), only water is recommended

. In summary, stick to water, black coffee, plain tea, and zero-calorie flavored waters like lemon or sparkling water during your fasting window to maintain the fasted state and hydration effectively.