Bone broth breaks a fast. It contains protein, fat, and calories that raise insulin, so it ends a fast, though it is a gentle option for breaking longer fasts.
| Calories | ~30-50 kcal per cup |
|---|---|
| Breaks a weight-loss fast? | Yes |
| Breaks ketosis? | No |
| Breaks autophagy? | Yes |
| Insulin impact | Yes |
Bone broth provides protein, some fat, and 30 to 50 calories per cup. The protein in particular raises insulin and switches off autophagy, so technically bone broth breaks a fast. It has little carbohydrate, so it will not knock you out of ketosis, but it still ends a true fast.
Despite breaking a strict fast, bone broth is widely used on multi-day fasts because it replaces electrolytes and makes the fast easier to sustain without spiking blood sugar. If your goal is maximum autophagy, avoid it; if your goal is getting through a long fast comfortably, a cup of broth is a reasonable compromise.
On a 16:8 fast it breaks the window, so save it for your eating window; on multi-day fasts a cup can be a deliberate compromise.
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