I say black coffee or tea no sweeteners or flavorings. Two cups worth of coffee in my thermos for the morning and then water the rest of the day. Creamer contains calories and flavor taking away from fasting, well in my opinion but then again in most cases I’d say it does so just have it plain. If day black coffee and you’ll learn to work with it, otherwise tea without adding sweeteners. And no diet soda, that’s clearly cheating to me and plus I heard studies say that flavoring sets off taste receptors in the brain making you feel like you’re taking in calories so it’s just not worth doing. Stick with water and you’ll be fine, hunger will naturally become suppressed in my opinion as you progress with intermittent fasting. I do 18 hour fasting and 6 hiur eating window so 8pm to 2pm the next day I fast, and then break my fast at 2pm or later at my work lunchbreak depending if it gets busy then it will be a longer fasting period like closer to 20 hours and that much less of an eating window. Hope this helps our. Stay hydrated and stay strong with the progress
Better if you just keep it simple and drink it black. You’ll get used to it. Drinking black coffee is better if you drink better quality stuff, and light or medium roast instead of dark roast, since you taste it a lot more since it’s not masked with creams and sweeteners. You could add cinnamon to it for some flavor though. I don’t believe that would provoke an insulin response.