Does bone broth break a fast?
Yes. A cup of bone broth carries meaningful protein and calories, so it ends a fasted state. Whether that matters depends on what you are fasting for.
This is the question where the honest answer is not the popular one. Bone broth is often sold as fast-friendly, but a cup carries real protein and a real calorie load. By any definition that involves not eating, it counts as eating.
Whether that is a problem depends on your goal. If you are fasting to manage overall intake and appetite, a cup of broth is a small cost and it genuinely helps people get through a long fast. If you are specifically chasing a prolonged fasted state, it is not a free pass.
It is a good first thing to have when you break a longer fast, which is a different job entirely: warm, salty, easy to digest, and gentle on a stomach that has been empty for a while.
General information, not medical advice. Intermittent fasting is not right for everyone. Talk to a clinician before starting if you are pregnant or breastfeeding, have or have had an eating disorder, have diabetes, or take prescription medication.