Does monk fruit break a fast Dr. Berg?

December 3, 2025 •

4 min read

Multiple sources confirm that pure monk fruit is a zero-calorie, natural sweetener that does not raise blood glucose or insulin levels. In alignment with this, Dr. Berg has stated that monk fruit is generally considered acceptable for most fasting goals.

Quick Summary

Pure monk fruit sweetener, a favorite of Dr. Berg, does not contain calories or carbohydrates and will not spike insulin, making it suitable for most fasts. The key is using pure extract and avoiding blends with hidden sugars like maltodextrin that can end ketosis.

Key Points

Dr. Berg's Approval: Dr. Berg confirms pure monk fruit is acceptable during most fasts because it does not cause an insulin spike.
The Insulin Rule: The primary determinant of whether a substance breaks a fast, according to Dr. Berg, is its effect on insulin, not just its caloric count.
Read Ingredients Carefully: The biggest risk comes from monk fruit blends containing high-glycemic fillers like maltodextrin or dextrose, which must be avoided.
Zero Calorie, Zero Carb: The mogrosides in pure monk fruit are not metabolized by the body as sugars, so they do not provide energy or trigger an insulin response.
Goals Matter: While safe for weight loss and ketosis, use with caution if fasting for gut rest, as trace absorption may occur.
Cravings Management: Be mindful of using any sweetener, even a non-caloric one, as it can potentially increase sugar cravings over time.

Dr. Berg's Take on Monk Fruit and Fasting

Dr. Eric Berg, a prominent figure in the keto and intermittent fasting communities, frequently addresses questions about sweeteners during a fast. His guidance is consistent: the primary concern is whether a substance elicits an insulin response, which would halt the fat-burning state of ketosis. Pure monk fruit sweetener, derived from the mogrosides of the monk fruit, contains no calories or carbohydrates that would cause such a spike. This is why he includes it, along with stevia and erythritol, on his list of fast-friendly sugar alternatives.

He explicitly warns against the common pitfall of monk fruit blends. Many commercial products combine monk fruit with high-glycemic fillers like maltodextrin or dextrose to improve taste and bulk. These additives can raise blood sugar levels even more aggressively than regular sugar, completely defeating the purpose of a fast. This is a critical distinction and a point Dr. Berg emphasizes when advising on sweeteners.

The Science Behind Monk Fruit and Insulin

The sweetness in monk fruit comes from mogrosides, which are powerful antioxidants, not sugars. The body does not metabolize these compounds for energy or recognize them as carbohydrates. This allows them to pass through the digestive system without impacting blood glucose or insulin levels. Clinical studies have shown that monk fruit sweeteners do not cause significant spikes in blood glucose or insulin. This metabolic pathway is why it is safe for individuals with diabetes and those following ketogenic diets. It is this zero-calorie, zero-glycemic impact that solidifies monk fruit's reputation as a safe sweetener during fasting for weight loss and ketosis.

Reading Labels: The Most Important Step

The risk of using monk fruit during a fast comes almost entirely from what manufacturers add to the product. A quick scan of the ingredients list is necessary to ensure it aligns with your fasting goals. Here’s what to look for on the label:

Safe Ingredients: Pure monk fruit extract, erythritol, and stevia are generally safe and won't break a fast.
Harmful Fillers to Avoid: Dextrose, maltodextrin, cane sugar, and honey will cause an insulin spike and should be avoided during a fast.

Monk Fruit and Different Fasting Goals

The impact of monk fruit can vary slightly depending on your specific fasting goals. For instance, while generally safe for metabolic health, it requires a little more consideration for deeper, cellular-level goals like autophagy and gut rest.

Weight Loss & Ketosis: For most people, monk fruit is perfectly fine. Since it doesn't cause an insulin response, it preserves the fat-burning state needed for weight loss and ketosis.
Autophagy (Cellular Repair): As a non-nutritive, zero-protein substance, monk fruit is unlikely to significantly interfere with autophagy. Some animal studies even suggest mogrosides may activate AMPK, a signaler involved in autophagy.
Gut Rest: The consensus is less clear regarding gut rest. Some studies suggest trace amounts of mogrosides may be absorbed, potentially interfering with a purely digestive rest. For a strict gut rest, some recommend avoiding all sweeteners, including monk fruit.

Sweetener Comparison for Fasting


Feature	Monk Fruit (Pure)	Stevia (Pure)	Erythritol	Artificial Sweeteners (e.g., Splenda)
Calorie Impact	Zero calories	Zero calories	Minimal calories (0.24 kcal/g)	Zero calories (but with high-glycemic fillers)
Insulin Response	No significant spike	No significant spike	No significant spike	Potential spike from fillers like maltodextrin
Carbohydrate Content	Zero carbs	Zero carbs	Minimal net carbs	Variable, can contain high-glycemic carbs
Dr. Berg's View	Approved, with caution on blends	Approved, with caution on blends	Approved, generally well-tolerated	Avoid due to fillers and potential metabolic disruption
Safety for Gut Rest	Potential minor impact	Generally safe	Breaks gut rest due to absorption	Avoid

Practical Tips for Fasting with Monk Fruit

Choose Pure Extracts: Always opt for products containing 100% monk fruit extract or a blend with only safe sugar alcohols like erythritol.
Read Labels Diligently: As Dr. Berg advises, check for hidden sugars and other fast-breaking additives.
Use in Moderation: Even if a sweetener doesn't break a fast, excessive use can trigger cravings for sweet foods, making adherence to fasting more difficult.
Test Your Body: Some individuals are more sensitive to non-nutritive sweeteners. If you notice unusual cravings or a physical response, consider cutting it out to see if it helps.

For more information on fasting and acceptable liquids, you can refer to Dr. Berg's blog What Can I Drink During a Fast? | Dr. Berg.

Conclusion

For most fasting protocols aimed at weight loss, ketosis, and metabolic health, pure monk fruit will not break your fast, a view consistent with Dr. Berg's advice. The mogrosides that provide sweetness do not affect blood sugar or insulin levels. The critical factor is to ensure you are using a clean product, free from fast-breaking additives and fillers like maltodextrin. By carefully reading labels and using it in moderation, monk fruit can be a valuable tool to help you stay compliant with your fasting goals, as confirmed by Dr. Berg and supported by scientific evidence.

Frequently Asked Questions

Dr. Berg approves monk fruit because its sweetening compounds, mogrosides, are non-caloric and do not raise blood sugar or spike insulin levels. He teaches that avoiding an insulin response is key to maintaining a fasted state for fat-burning.

Pure monk fruit and erythritol are both generally considered safe for fasting and keto, as they have minimal impact on blood sugar and insulin. Dr. Berg includes both on his list of acceptable sweeteners.

Pure monk fruit is the extract of the fruit's mogrosides. A monk fruit blend, however, is often cut with bulking agents like maltodextrin, dextrose, or other fillers. It is these additives, not the monk fruit itself, that can break a fast.

Yes, adding pure monk fruit to your coffee is acceptable during fasting, as it won't add calories or cause an insulin spike. Dr. Berg approves of sweeteners like monk fruit for black coffee and tea.

No, pure monk fruit will not knock you out of ketosis. Since it does not raise blood sugar or insulin, it allows your body to remain in a fat-burning state.

Dr. Berg generally recommends both monk fruit and stevia as good natural, zero-calorie options for fasting and keto. The choice between them often comes down to individual taste preference, though some people find stevia has a stronger aftertaste.

Always read the nutritional label and ingredients list. Look for products that list only 'monk fruit extract' or a blend with 'erythritol' or 'stevia.' Avoid any products containing sugars or maltodextrin.