CoffeeBox discusses black coffee within a sixteen-hour fasting and eight-hour eating pattern. The question of whether it breaks a fast needs context: a self-chosen eating schedule, a research protocol, religious practice and clinical fasting can have different requirements. A supposed universal calorie threshold does not resolve all of them.
Plain coffee differs from a latte or a drink with sugar, cream or butter, but that distinction does not prove a promised effect on fat loss, insulin or cellular autophagy. Laboratory or animal findings are not a direct measurement of those processes in a person drinking a morning cup. Coffee should not be presented as a way to guarantee the benefits attributed to fasting.
For a blood test or procedure, follow the healthcare team's exact instructions; water-only guidance does not allow coffee simply because it is black. Do not alter prescribed medicines or undertake a restrictive eating plan based on a coffee article. Where the question is simply a personal beverage routine, clarify the goal and the rules being followed before choosing. This is an explanation of the distinction, not a fasting or weight-loss prescription.

The conversation
A good question can make a better brew.