“Will this break my fast” questions aren’t as clear cut as they might seem, because people fast for different reasons and with different goals. Are you fasting for GI rest? Autophagy? Weight loss?
I’m ok with black coffee and water with lime juice on a fast. I’ve found that artificial sweeteners seem to make me feel hungry, so I avoid them while fasting.
(My latest discovery is a sparkling water flavored with hops, which has zero calories and no artificial sweeteners, but somehow scratches the itch for a hoppy beer.)
So I would say for me, personally, a Coke Zero is a fast-breaker, but I think the answer to that question is a lot less clear cut than you’d think.
Coca-Cola Zero Sugar (Coke Zero) uses several common artificial sweeteners, including aspartame and acesulfame potassium (Ace-K).
Aspartame: The oldest and most studied sweetener, aspartame has zero grams of sugar and won’t spike insulin levels after it’s consumed.
The answer is no. The logic is very simple. Your body did not receive any energy to “break” your fast. The fact that no insulin was produced to burn glucose for energy is the answer to your question. For those who claim it breaks the fast, please explain where did the energy come from? No increase in insulin to burn the drink for energy, the body continues to use your stored fats, so how does it break the fast?
Studies did show it causes unwanted food and sugar cravings from the stimulated cephalic response. So it might make your fast a bit tougher.
I totally drink diet cokes and sparkling water. It might not let you reach autophagy, but your fast will be fine. Be mindful that it can (and I can attest to this) make you hungry with how sweet it is.
It probably won’t break your fast, but, the stevia/non-sugary sugars in there create a false sense of sugar in system which leads to a rise in insulin and a lowering of ghrelin horomone making you crave carbs… so up to you, if you feel like it helps your fast without inducing your hunger cravings, then have at it!