Does Bone broth break a fast?
Bone broth breaks a fast. It provides meaningful calories or triggers an insulin response that ends the fasted metabolic state.
Calories
~30–50 kcal per 240 ml cup (varies by preparation)
Why — the calorie and insulin logic
Bone broth contains protein (primarily collagen/gelatin peptides), fat, and small amounts of minerals. Even a cup provides 30–50 kcal and a meaningful dose of amino acids — particularly glycine and proline — that stimulate insulin secretion and activate digestive processes. It clearly ends a fast from a caloric and metabolic standpoint.
Does it depend on your fasting goal?
Bone broth breaks a fast for autophagy (protein/amino acids activate mTOR) and for strict metabolic fasting (amino acids and calories trigger insulin). Some extended-fast practitioners use bone broth as a 'modified fast' to replace electrolytes and prevent muscle loss while fasting for 3–5+ days — this is a different practice from standard 16:8 or 18:6 intermittent fasting.
Frequently asked questions
- Does bone broth break intermittent fasting?
- Yes. Bone broth contains protein and calories that trigger insulin and end a metabolic fast. It is not suitable for the fasting window of a 16:8 or 18:6 protocol.