I am asking out of two reasons:
1. I do not trust there is such a thing as zero-calorie drink
2. Artificial flavour in zero-calorie energy drink may break fasting
Answer
Anything that’s not plain green/black tea, black coffee, or unflavored water breaks a fast no matter if there’s zero calories or not. It’s not the calories, it’s the artificial flavors that break the fast by triggering an insulin response.