i’m drinking some as we speak and started a fast today. since i fast primarily for weight loss currently i don’t mind it. it helps me with cravings when i’m starting out.
but if you’re trying to get full benefits it probably gets in the way a tiny bit.
It depends on your definition of fasting.
Coffee doesn’t have calories. So, no, it does not break a fast, just like diet soda does not.
Caffeine and other trace components of coffee require the body to first metabolize those supstances, activating your circadian cycle, which in humans is 10-12 hours long. So, yes, it does break a fast, just like diet soda does.
Opinion: When I fast I also caffeine detox so my preworkout hits harder. However, I also go by Stan Efferding’s recommendations and dose 500-600mg of caffeine. I stay away from coffee and other sources of caffeine so my workouts get the fullest effect.
I drink water and black coffee in my fasts. Since it does not have calories or artificial sweeteners, I do not see the harm. I guess, as argued in another comment, it could be considered breaking a fast but I do not see it in that way - especially if it keeps you fasting!
But… One day, I would like to fast with nothing other than water; no (required) medication or substances, no coffee or green teas, etc…
However, it seems there is a wide consensus that black coffee is perfectly fine! I do not think it interferes with autophagy (definitely not ketosis either) and black coffee CAN speed up weightloss when cutting. Additionally, black coffee contains many antioxidants!
What is the purpose of your fast? This may help answer.
On the Joe Rogan podcast, Dr. Rhonda Patrick said that coffee is uptaken by the liver and begins a set of metabolic processes. Not only is she super smart, and knows her stuff, she’s interviewed several top scientists whose focus is in fasting, like Dr. Satchin Panda.
And yes I’m bummed about it too.