Does Collagen Break a Fast?
Technically, collagen contains calories from protein, so a strict interpretation says it breaks a fast. Whether that matters depends on why you're fasting. If your goal is purely time-restricted eating for simplicity, a scoop of collagen in black coffee is a small amount many people don't worry about. If you're fasting for specific metabolic reasons, the protein does provide calories and amino acids, so it isn't a "zero" the way black coffee or water is.
The honest answer: it depends on your fasting goal, and this is genuinely a question for a professional if you're fasting for health reasons rather than habit. We're not going to give blanket fasting advice. If strict fasting matters to you, take collagen during your eating window to be safe. More in our collagen explainer.
This article is general information, not medical advice.