When fasting, it is important to drink calorie-free beverages that will not activate an insulin response or break your fast. Here are some drinks that you can consume during a fast:

• Water: Plain or carbonated water contains no calories and will keep you hydrated during a fast.

• Tea: Unsweetened tea is a good option during a fast. Black, green, oolong, lapsang souchong, and all manner of herbal teas are acceptable.

• Coffee: One cup of black coffee is okay during your fasting window, but consider other beverage options if you get thirsty again. It is best to brew your coffee at home. If you must drink coffee from coffee shops, remember to explicitly tell them not to add anything extra if you do not want to break your fast.

• Apple cider vinegar: Diluted apple cider vinegar mixed into water can help you stay hydrated and prevent cravings during a fast.

• Seltzer: Seltzer is one of the non-caloric drinks that you can take during your intermittent fast. Most brands contain natural flavors and will not raise insulin levels.

Here are some drinks that you should avoid during a fast:

• Alcohol: Alcohol should not be consumed during a fast, as its effects can intensify when consumed on an empty stomach. Alcohol is also a source of calories, which can break the fast and stimulate appetite and cravings.

• Diet sodas: Diet sodas should be avoided during a fast, as they contain artificial sweeteners that can trigger an insulin response and break the fast.

• Coconut water: Coconut water contains carbohydrates and should be avoided during a fast.

• Milk: Milk contains calories and carbs, which can break the fast and trigger an insulin response. One or two tablespoons of milk in your coffee or tea won’t bust you out of a fasted state, but a quarter cup or more will break your fast.

In summary, the best drinks to consume during a fast are water, tea, coffee, apple cider vinegar, and seltzer. It is important to avoid drinks that contain calories, artificial sweeteners, or carbohydrates, as they can break the fast and trigger an insulin response.