Does Bone Broth Break a Fast? The Surprising Truth (for Keto & Carnivore)

Have you ever found yourself standing in your kitchen during a fast, staring at a steaming cup of bone broth and wondering, “Am I about to undo all my fasting efforts?” You’re not alone. The question of whether bone broth breaks a fast is one of the most hotly debated topics in the fasting community—especially among those following keto and carnivore lifestyles.

The answer isn’t as simple as yes or no. In fact, it depends entirely on why you’re fasting in the first place. In this comprehensive guide, we’ll cut through the confusion and give you the evidence-based insights you need to decide whether bone broth belongs in your fasting protocol.

What Does “Breaking a Fast” Actually Mean?

Before we can determine if bone broth breaks a fast, we need to understand what “breaking a fast” actually means. The truth is, it varies depending on your fasting goals:

1. Strict Zero Calorie Intake: The purist definition—absolutely nothing with calories enters your body.
2. Avoiding Insulin Response: Preventing significant insulin spikes to maintain metabolic benefits and fat burning.
3. Maximizing Autophagy: Supporting your body’s cellular cleanup process.
4. Maintaining Deep Ketosis: Preserving the fat-burning state central to carnivore diet ketosis.
5. Giving the Digestive System Rest: Allowing your gut complete downtime.

Each goal has different thresholds for what constitutes “breaking” the fast, which is why there’s so much confusion around this topic.

Bone Broth’s Nutritional Profile (Relevant to Fasting)

To understand how bone broth affects your fast, we need to examine what’s actually in it:

Calories

Bone broth is not calorie-free. A typical cup contains approximately 10-50 calories, depending on preparation methods and ingredients. While this is minimal compared to a meal, it’s definitely not zero.

Macronutrients

Bone broth primarily contains:

• Protein: Mainly collagen and gelatin (about 5-10g per cup)
• Fat: Variable amounts (0.5-5g per cup), especially if not defatted
• Carbohydrates: Nearly negligible, particularly if using a carnivore bone broth recipe

Insulin Impact

Bone broth typically has minimal impact on insulin levels due to its low carbohydrate content. However, it’s worth noting that protein can trigger a small insulin response. The amount in bone broth is usually insufficient to cause significant insulin spikes for most people, but it’s not completely neutral either.

Amino Acids

Bone broth contains various amino acids including glycine, proline, and glutamine. These compounds are beneficial for gut health and joint support but play an important role in the mTOR/autophagy discussion we’ll explore shortly.

Bone Broth’s Impact on Different Fasting Goals

Now for the big question: Does bone broth break your fast? Let’s analyze this goal by goal:

Goal: Zero Calorie / Water Fast

Verdict: Yes, it breaks this strict definition.

If you’re following a strict water fast that permits absolutely zero calories, then bone broth definitely breaks this fast. There’s no gray area here—bone broth contains calories, period.

Goal: Digestive Rest

Verdict: Technically interrupts complete rest.

Consuming bone broth does require some digestive processing, so it technically interrupts complete digestive rest. However, it’s much gentler on your system than solid food. Many people use bone broth therapeutically during modified fasts specifically to support gut health while still giving the digestive system substantial rest.

Goal: Maintaining Ketosis

Verdict: Generally NO, does NOT break ketosis.

Good news for keto enthusiasts—bone broth is unlikely to knock you out of ketosis. With its negligible carb content and moderate protein levels, it’s completely compatible with ketogenic metabolism. In fact, it can be supportive by providing electrolytes often depleted during ketosis and fasting.

Many people on the carnivore diet use bone broth specifically to enhance their ketogenic state by providing essential minerals without significant carb impact.

Goal: Maximizing Autophagy

Verdict: Likely YES, it reduces autophagy (to some degree).

This is where the answer gets more complex. To understand how bone broth impacts autophagy, we need a quick biology lesson:

1. Autophagy is your body’s cellular cleanup process that ramps up during nutrient deprivation.
2. The mTOR pathway (mechanistic Target Of Rapamycin) acts as a nutrient sensor that inhibits autophagy when activated.
3. Amino acids, particularly those found in protein sources like bone broth, can activate mTOR.
4. Therefore, consuming bone broth likely blunts or temporarily reduces peak autophagy.

Think of it this way: On a spectrum between drinking black coffee (generally considered to have negligible impact on autophagy) and consuming a protein shake (clear mTOR activation), bone broth falls somewhere in between—likely closer to having some impact, but not completely shutting down the process.

The exact degree of impact is still debated in scientific circles, and most research has been conducted on animals rather than humans. However, there’s reasonable evidence to suggest that the amino acids in bone broth would at least partially reduce autophagy.

Goal: Weight Loss / Hunger Management / Fasting Sustainability

Verdict: Often BENEFICIAL.

If your primary goal is weight loss or making fasting sustainable long-term, bone broth can be incredibly helpful:

1. It provides satiety with minimal calories—warm liquid with small amounts of protein and fat can reduce hunger significantly.
2. It replenishes vital electrolytes—reducing fatigue, headaches, and other unpleasant fasting side effects.
3. It makes longer fasting periods more tolerable—many people find they can extend their fasts substantially when they include bone broth.

For those struggling to stick with intermittent fasting, bone broth can be the difference between success and failure.

Bone Broth in Different Fasting Protocols

Bone broth fits differently into various fasting approaches:

Intermittent Fasting (IF – e.g., 16/8, OMAD)

During your fasting window on intermittent fasting, the decision to include bone broth should align with your primary goal:

• Avoid: If maximizing autophagy is your sole focus for that specific fasting period
• Consider including: If your goals are maintaining ketosis, hunger control, or simply making IF more sustainable

Many people doing carnivore diet and intermittent fasting include bone broth in their routine and still achieve excellent results.

Prolonged Fasting (24+ hours)

During extended fasts, bone broth is commonly used as a “modified fast” tool. Its primary purpose is electrolyte replenishment and fasting sustainability.

Users typically accept the potential reduction in peak autophagy benefits in exchange for the ability to complete a longer fast safely and more comfortably. If you’re doing a multi-day fast and concerned about when does autophagy start, bone broth may delay the process somewhat, but the extended fasting duration may still provide substantial benefits.

The Verdict: Does Bone Broth Break a Fast? (It Depends!)

Let’s summarize what we’ve learned:

The bottom line? There’s no one-size-fits-all answer. The effect of bone broth on your fast depends entirely on YOUR specific reason for fasting.

Practical Recommendations (When to Use vs. Avoid)

Use Bone Broth If:

• You’re easing into fasting and need support transitioning
• Managing hunger is your primary challenge
• You need electrolyte replenishment during longer fasts
• Gut health support is a priority during modified fasts
• You want to maintain ketosis while fasting
• You’re experiencing fasting-related symptoms like headaches or fatigue
• You’re using fasting primarily for weight loss rather than autophagy

Avoid Bone Broth If:

• Your absolute priority is achieving the deepest possible state of autophagy
• You’re adhering to a strict water-only fast for specific therapeutic purposes
• You’re doing a digestive rest protocol that prohibits any food substances

Listen to Your Body

The best approach is often to experiment and observe how your body responds. Some questions to ask yourself:

• Do you feel better when including bone broth in your fast?
• Are you achieving your desired outcomes with or without it?
• Does bone broth help you maintain fasting consistency?

Remember that fasting benefits exist on a spectrum—it’s not all-or-nothing. Even if bone broth slightly reduces certain benefits, the ability to fast consistently and for longer periods might outweigh those considerations.

Conclusion

The question “Does bone broth break a fast?” isn’t binary. The answer depends on your definition of fasting and your specific goals. For many people following keto and carnivore lifestyles, bone broth can be a valuable tool that makes fasting more sustainable without significantly compromising the primary benefits they’re seeking.

If you’re interested in incorporating bone broth into your fasting routine, consider making your own high-quality carnivore bone broth to ensure you know exactly what’s in it and to maximize nutritional benefits.

What’s your take? Do you use bone broth during your fasts? Share your experience below! And if you’re interested in learning more about how fasting impacts other aspects of health, check out our article on does fasting increase testosterone for more insights.

Disclaimer: This article is for informational purposes only and should not be considered medical advice. Always consult with a healthcare professional before making significant changes to your diet or fasting regimen, especially if you have underlying health conditions.

For the autophagy section:

• National Institutes of Health: Autophagy research – Scientific review on fasting and autophagy mechanisms
• Cell Journal: mTOR Signaling in Growth and Metabolism – Research on how amino acids affect mTOR pathway

For fasting benefits:

• New England Journal of Medicine: Effects of Intermittent Fasting on Health and Aging – Comprehensive review of fasting research
• Harvard Health: Intermittent Fasting – Accessible overview of fasting benefits

For bone broth nutritional information:

• USDA Food Data Central: Bone Broth Nutrition – Official nutritional composition data
• Journal of Clinical Nutrition: Collagen and Amino Acid Content – Research on collagen protein composition

For insulin response information:

• American Diabetes Association: Protein and Insulin – Research on how proteins affect insulin
• Journal of Nutrition: Impact of Different Macronutrients on Insulin Response – Comparison of how different nutrients affect insulin

For ketosis information:

• Frontiers in Physiology: Ketogenic Diet Research – Scientific review of ketosis mechanisms
• Diet Doctor: Guide to Ketosis – Accessible explanation of ketosis for your readers