Ingesting Athletic Greens does not break a fast for most people because it contains minimal carbohydrate or sugar.

“for most people, including me, because I've measured it, ingesting Athletic Greens does not break a fast and if it happens to break a fast, it would be a very transient break in fast. So without knowing your resting blood glucose levels on an individual basis, there's no way I can say for sure that it doesn't break a fast, but chances are it does not because it doesn't contain much carbohydrate or sugar and it doesn't tend to therefore pull you out of the molecular mill you associated with low blood glucose states.”