How long should you fast for inflammation? A comprehensive guide

October 14, 2025 •

4 min read

While fasting is not a new concept, modern research is shedding light on its potential to modulate the body's inflammatory responses. The key to understanding how long should you fast for inflammation lies in differentiating between types of fasting and recognizing that not all protocols are equal or suitable for everyone.

Quick Summary

Studies reveal that moderate, regular intermittent fasting, particularly time-restricted eating, can reduce inflammatory markers and improve metabolic health. Conversely, evidence suggests prolonged fasting (over 48 hours) may cause an acute, temporary increase in inflammation, although markers can drop below baseline upon refeeding. Fasting's effects are complex and depend on duration, protocol, and individual health status. An anti-inflammatory diet complements these benefits.

Key Points

Intermittent fasting is generally effective for chronic inflammation: Time-restricted eating (e.g., 16:8, 14:10) and alternate-day fasting have shown consistent benefits by reducing inflammatory markers over time.
Prolonged fasting (48+ hours) may initially increase inflammation: Studies show that during extended fasts, inflammatory markers like CRP may rise, which could be a temporary, adaptive stress response.
Refeeding is crucial after a prolonged fast: The potential anti-inflammatory benefits of prolonged fasting are more likely to occur after the fast is broken, when inflammatory markers can drop below baseline.
Fasting works by modulating immune cells and gut health: Intermittent fasting reduces circulating pro-inflammatory monocytes and supports a healthier gut microbiome, which can lead to a long-term reduction in inflammation.
Combine fasting with a balanced diet: To maximize anti-inflammatory effects, fasting should be paired with a diet rich in fruits, vegetables, and healthy fats, while avoiding processed and sugary foods.
Fasting is not suitable for everyone: People with diabetes, eating disorders, or those who are pregnant or breastfeeding should avoid fasting without professional medical guidance due to potential health risks.

The Link Between Fasting and Inflammation

Chronic, low-grade inflammation is a contributing factor to numerous health conditions, including heart disease, type 2 diabetes, and autoimmune disorders. Intermittent fasting, which involves cycling between periods of eating and abstaining from food, has gained popularity as a dietary strategy to combat this chronic inflammation. During fasting, the body undergoes several cellular changes that can affect the immune system and its inflammatory pathways.

One of the primary mechanisms involves the suppression of the NLRP3 inflammasome, a multi-protein complex that triggers inflammatory responses. Fasting has been shown to increase levels of arachidonic acid, a chemical that inhibits the activity of this inflammasome. Fasting also appears to influence immune cells directly. A study at Mount Sinai found that intermittent fasting reduced the number of pro-inflammatory monocytes circulating in the blood, and that these cells were less inflammatory than those from non-fasting individuals.

Intermittent Fasting: A Measured Approach to Reducing Inflammation

For most people looking to leverage fasting's anti-inflammatory benefits, moderate intermittent fasting appears to be the most consistent and safer approach. Unlike prolonged fasts, which can induce stress responses, intermittent fasting works gradually to improve metabolic and immune function.

Common intermittent fasting protocols:

Time-Restricted Eating (TRE): This is one of the most studied and accessible forms of intermittent fasting. Popular schedules include the 16:8 and 14:10 methods, where eating is confined to a specific window of 8 to 10 hours daily. Research suggests that TRE can significantly reduce inflammatory markers like interleukin-6 (IL-6), interleukin 1-beta (IL-1β), and TNF-alpha after several months.
Alternate-Day Fasting (ADF): This involves alternating between a normal eating day and a "fasting" day where either no calories or a very low number (e.g., 500 calories) are consumed. Studies on ADF have shown reductions in C-reactive protein (CRP), a key inflammatory marker, particularly when combined with at least 6% weight loss.
The 5:2 Method: With this approach, individuals eat normally for five days of the week and restrict calories to 500-600 on the other two non-consecutive days. This method offers a more flexible way to achieve periodic caloric restriction and can help reduce inflammatory pathways over time.

Prolonged Fasting: A Higher-Risk Strategy

While shorter, consistent fasts have shown positive anti-inflammatory effects, the impact of prolonged fasting (defined as over 48 hours) is more complex and potentially more risky. Recent systematic reviews have highlighted that during a prolonged fast, inflammatory markers often paradoxically increase. This may be an adaptive physiological stress response.

Potential for a pro-inflammatory spike: A 2025 review found that most studies show a rise in CRP, IL-6, and TNF-α during fasts of 48 hours or longer, with especially pronounced increases in those with overweight or obesity.
Normalization after refeeding: Crucially, some studies show these elevated markers return to baseline or even decrease below it after a refeeding period. This suggests the inflammatory spike might be a temporary effect of the stress on the body. However, the outcomes are inconsistent and highlight the need for further research.
Increased risks: Prolonged fasting comes with risks such as malnutrition, muscle loss, fatigue, headaches, and for at-risk individuals, increased cardiovascular risk due to elevated inflammatory markers.

Comparison of Fasting Approaches for Inflammation


Feature	Intermittent Fasting (e.g., 16:8, 5:2)	Prolonged Fasting (48+ Hours)
Typical Duration	12-24 hours, regularly repeated	Continuous 48 hours or longer, done rarely
Effect on Inflammation	Consistently shown to reduce markers like CRP and IL-6 over time.	May cause an acute increase in inflammatory markers during the fast.
Risk Profile	Generally considered lower risk for most healthy adults.	Higher risk of nutrient deficiencies, muscle loss, and adverse side effects.
Safety Considerations	Requires proper hydration and nutrient-dense eating during windows.	Should only be undertaken with medical supervision, especially for high-risk individuals.
Mechanism	Promotes anti-inflammatory monocytes and optimizes gut health.	Involves a complex, potentially adaptive pro-inflammatory stress response.
Accessibility	Easier to integrate into daily life and sustain long-term.	Difficult to sustain, requires a significant lifestyle commitment.

The Importance of Diet Beyond Fasting

Fasting is a tool, not a cure-all. For sustainable reduction of chronic inflammation, it must be paired with an overall anti-inflammatory diet. This involves eating whole, unprocessed foods and avoiding pro-inflammatory ones.

Best practices for an anti-inflammatory diet:

Eat nutrient-dense foods: Prioritize fruits, vegetables, nuts, seeds, and healthy fats like olive oil.
Include oily fish: Consume oily fish, such as salmon and mackerel, for their omega-3 fatty acids.
Avoid processed foods: Minimize intake of processed and fried foods, sugary drinks, and refined carbohydrates, which can fuel inflammation.
Prioritize a healthy gut: Since gut health is strongly linked to immune response, incorporating fermented foods and prebiotics can be beneficial.

A Conclusive Answer for Inflammation

In conclusion, for most individuals seeking to mitigate chronic inflammation, consistent, shorter periods of intermittent fasting (such as the 16:8 or 5:2 method) are generally the best approach. These methods have a lower risk profile and more consistent evidence of long-term anti-inflammatory benefits compared to prolonged fasts. Prolonged fasting (48+ hours) is a higher-risk strategy with more variable outcomes regarding inflammatory markers and should only be pursued with medical oversight. When combined with a nutrient-dense, anti-inflammatory diet and healthy lifestyle choices like exercise and stress management, fasting can be a powerful tool for promoting overall wellness and reducing inflammation.

Safety First: Who Should Avoid Fasting?

Fasting is not suitable for everyone. Certain individuals should avoid fasting or only attempt it under strict medical supervision. These include:

Individuals with diabetes or blood sugar control issues: Fasting can lead to dangerous fluctuations in blood sugar.
Pregnant or breastfeeding women: Adequate nutrition is critical during these life stages.
Those with a history of eating disorders: Fasting can trigger or exacerbate disordered eating patterns.
Individuals who are underweight or nutrient deficient: Fasting can worsen these conditions.
People taking certain medications: Some drugs, including insulin, blood pressure medication, and blood thinners, require regular food intake.

It is always recommended to consult with a healthcare professional before beginning any new fasting regimen.

Frequently Asked Questions

For reducing chronic inflammation, research generally supports intermittent fasting protocols, such as time-restricted eating (12–24 hours daily) or the 5:2 method, as they show consistent anti-inflammatory effects over time with a lower risk profile.

Yes, several recent studies suggest that prolonged fasting (48 hours or more) can lead to an acute, temporary increase in inflammatory markers like C-reactive protein (CRP), especially in overweight individuals. However, markers may normalize or decrease below baseline after the refeeding period.

During intermittent fasting, the body reduces the release of pro-inflammatory immune cells called monocytes into the bloodstream. These cells also become less inflammatory during fasting, a process that helps to suppress the body's overall inflammatory state.

Yes, studies indicate that the inflammatory response to fasting can differ based on an individual's health status. The transient inflammatory increase during prolonged fasting is often more pronounced in overweight or obese individuals. Weight loss achieved through intermittent fasting, especially in overweight individuals, can significantly reduce inflammatory markers like CRP.

The anti-inflammatory effects are not instantaneous and typically manifest over a period of weeks or months of consistent practice. For example, some studies on intermittent fasting have observed reduced inflammatory markers after 8 to 12 weeks.

To break a fast effectively and support an anti-inflammatory response, it is best to start with a light, nutrient-dense snack, such as almonds. A diet focused on whole, anti-inflammatory foods like fruits, vegetables, and healthy fats is crucial, while avoiding processed foods and sugar.

Yes, combining a nutrient-dense, anti-inflammatory diet (rich in fruits, vegetables, and healthy fats) with intermittent fasting is a highly effective strategy for reducing chronic inflammation. Fasting's effects on metabolic function and immune response complement the anti-inflammatory properties of a healthy diet.

Yes, research shows that both intermittent and prolonged fasting can positively modulate the gut microbiome. Fasting may increase beneficial bacterial populations, which can reduce the production of pro-inflammatory metabolites and support healthy immune function.