Does a 72 hour fast reduce inflammation? Understanding the Science

October 11, 2025 •

4 min read

While popular discourse often suggests a direct link between extended fasting and reduced inflammation, scientific evidence presents a more intricate picture [1, 3]. Research indicates that the body's response to a 72 hour fast can be multifaceted, with potential temporary increases in inflammatory markers in some individuals [1, 3]. Understanding this complexity is vital for those considering prolonged fasting.

Quick Summary

Studies on prolonged fasting and inflammation show varied results. While some research suggests a potential for reduced inflammation through mechanisms like autophagy, an initial increase in inflammatory markers during a 72-hour fast is also possible. These findings underscore the need for further research and caution.

Key Points

Complex inflammatory response: Research suggests that the body's inflammatory response during a 72-hour fast can be complex, and a temporary increase in inflammatory markers is possible [1, 3].
Potential mechanisms: Fasting is thought to influence inflammation through mechanisms such as impacting monocyte activity and activating autophagy [4, 6].
Varied study outcomes: Research on prolonged fasting and inflammation has yielded inconsistent results, highlighting the need for further investigation [1, 3].
Medical guidance is essential: Due to the potential physiological changes and risks associated with prolonged fasting, medical supervision is strongly recommended [7].
Individualized approach: The safety and effects of a 72-hour fast can vary greatly depending on individual health status and circumstances [7].

The Complex Relationship Between Fasting and Inflammation

For some time, fasting has been explored for potential health benefits, including aspects related to inflammation. However, the direct impact of a 72-hour fast on inflammation is a subject of ongoing scientific investigation with complex findings [1, 3]. The body's response to prolonged periods without food is a intricate process that can involve various physiological changes. While some mechanisms triggered by fasting are thought to have anti-inflammatory potential, the acute effects during a 72-hour period are not always a simple reduction in inflammation [1, 3].

Acute vs. Potential Longer-Term Effects of Prolonged Fasting

Distinguishing between the immediate effects during a fast and potential longer-term outcomes is important. Some research indicates that while certain markers may show changes during a fast, the more significant effects might be observed after refeeding or through repeated fasting cycles [1, 3]. The body's adaptive response to fasting can initiate cellular processes that, over time, may contribute to a reduction in inflammation.

Potential Mechanisms Investigated in Research

Monocyte activity: Research has explored how fasting might influence the activity of certain immune cells, like monocytes, which play a role in inflammation [4]. Studies have suggested a potential reduction in the number or activity of these cells with fasting [4].
Biochemical pathways: Investigations have looked into how fasting affects various biochemical pathways in the body. Some studies have identified specific chemicals, such as arachidonic acid, that may be influenced by fasting and could potentially inhibit inflammatory responses [5].
Metabolic changes: Fasting can lead to shifts in metabolic processes, including changes in insulin sensitivity and blood sugar levels [6]. Since chronic metabolic dysfunction is linked to inflammation, these changes are an area of interest [6].
Autophagy: This cellular process involves the body's cleanup and recycling of damaged components, and it is known to be activated during fasting [6]. Autophagy is believed to have potential anti-inflammatory effects [6].

The Data: Understanding the Research

Studies on prolonged fasting and inflammation have produced varied results, emphasizing the need for a nuanced understanding. Factors such as the study design, participant characteristics, and the specific inflammatory markers measured can influence the findings.

A Look at Study Outcomes Related to Fasting and Inflammation


Study Approach	Observed Changes in Inflammation during Fasting	Observed Changes after Refeeding	Research Insights
Prolonged Fasting Studies (e.g., ≥72 hours)	Some studies have reported temporary increases in inflammatory markers like C-reactive protein (CRP), particularly in certain populations [1, 3].	CRP levels in some studies have shown a tendency to normalize or decrease after a refeeding period [1, 3].	The initial inflammatory response during a prolonged fast can be complex and may be transient.
Intermittent Fasting Studies (e.g., shorter duration)	Research in this area has explored potential reductions in specific immune cells and inflammatory activity [4].	Anti-inflammatory effects have been a focus of these studies [4].	Shorter fasting periods may have different acute effects on inflammatory markers compared to prolonged fasting.
Modified Fasting Studies (calorie restriction)	Outcomes have varied, with some studies noting changes in CRP while others found no significant acute change [1].	CRP levels in these studies often showed normalization or decline after the refeeding phase [1].	The degree and type of calorie restriction can influence the body's inflammatory response during a fasting period.

Important Considerations Regarding Prolonged Fasting

Prolonged fasting, such as a 72-hour fast, is a significant physiological intervention that should not be undertaken without careful consideration and professional medical guidance. The body undergoes substantial changes during extended periods without food, and there are potential risks involved [7].

Medical Consultation: It is strongly recommended to consult with a qualified healthcare provider before considering a 72-hour fast, especially if you have any pre-existing health conditions [7]. A doctor can assess your individual health status and advise on the appropriateness and safety of such a practice.
Individual Responses Vary: The body's response to fasting is highly individual. Factors such as age, overall health, body composition, and lifestyle can all influence how a person reacts to prolonged calorie restriction [7]. What might be manageable for one person could be risky for another.
Potential Risks: Prolonged fasting carries potential risks, including electrolyte imbalances, dehydration, and in rare cases, refeeding syndrome upon reintroduction of food [8]. These complications can be serious and require medical attention [8].
Listen to Your Body: Paying close attention to physical sensations and any adverse symptoms is crucial during any period of fasting. If concerning symptoms arise, it is important to stop the fast and seek medical advice [7].

Conclusion

The question of whether a 72-hour fast directly reduces inflammation has a complex answer based on current research. While fasting can trigger mechanisms with potential anti-inflammatory benefits, studies also suggest that an initial increase in inflammatory markers is possible during the fasting period. The potential benefits are often discussed in the context of longer-term effects or the refeeding phase, and the scientific understanding is still developing. Given the significant physiological changes involved and the potential risks, prolonged fasting, including a 72-hour fast, should always be approached with caution and ideally under the supervision of a healthcare professional. Individual circumstances and health status are critical factors to consider before undertaking such a practice.

Disclaimer: This article provides general information and is not a substitute for professional medical advice. Always consult with a healthcare provider before making decisions about your health or diet, particularly regarding fasting.

Frequently Asked Questions

A 72-hour fast is not universally recommended. The decision to undertake prolonged fasting should be made in consultation with a healthcare professional, as it may not be suitable or safe for all individuals, particularly those with underlying health conditions [7].

Individuals with conditions such as diabetes (especially Type 1), heart problems, kidney disease, a history of eating disorders, or those who are pregnant or breastfeeding should generally avoid prolonged fasting unless specifically advised and monitored by a medical professional [7].

Some studies have indicated that a 72-hour fast can be associated with a temporary increase in certain inflammatory markers during the fasting period itself, particularly in some individuals [1, 3].

Autophagy is a cellular process activated by fasting that helps the body clear out damaged cells. This process is believed to have potential anti-inflammatory effects [6].

Intermittent fasting protocols (shorter daily or weekly fasting periods) and dietary changes focused on anti-inflammatory foods are often considered safer and more sustainable approaches for potentially influencing inflammation for many individuals [4, 7].

Symptoms such as severe dizziness, confusion, irregular heartbeat, chest pain, or extreme weakness are signs that a fast should be broken immediately, and medical attention should be sought [7].

Current scientific research on the direct and long-term effects of a 72-hour fast on chronic inflammation is still evolving and presents varied findings. While potential mechanisms are being explored, a definitive conclusion requires more comprehensive research [1, 3].