FiberNEW2026-08

Intermittent Fasting and the Gut Microbiota: Mechanisms Linking Microbial Remodeling to Metabolic and Immune Regulation.

Diaz-Garrido Natalia, Regaldiz Alejandro, Zagmutt Sebastián, Cisternas Pedro et al. — Nutrients

Summary

This paper explores how intermittent fasting, a popular eating pattern, influences the community of bacteria living in our gut. It suggests that changes in these gut bacteria might be a key reason why fasting can improve our metabolism and immune system. The review also looks at how specific food components like fiber could enhance these positive effects.

AI-generated summary — read the original

Key points

Intermittent fasting can change the types and balance of bacteria in your gut.
These changes in gut bacteria may contribute to improved metabolism and immune function.
Fasting influences gut bacteria by affecting their byproducts and their interaction with the body's internal clock.
Including dietary fiber and prebiotics might amplify the health benefits of intermittent fasting by supporting gut health.

What the study looked at

What question did the study ask? This review paper aimed to understand how intermittent fasting, an eating pattern that cycles between periods of eating and not eating, affects the bacteria living in our gut and how these changes might explain its reported health benefits for metabolism and immunity. How was it studied? This was a review article, meaning the authors synthesized and summarized findings from many existing scientific studies on intermittent fasting, gut microbiota, metabolism, and immune regulation. They examined research that explored how fasting influences the diversity and composition of gut bacteria, as well as the substances these bacteria produce. What did it find? The review found that intermittent fasting can indeed reshape the gut microbiota, leading to shifts in bacterial populations that are linked to better metabolic health. It highlighted that fasting affects important bacterial byproducts, like short-chain fatty acids, which play roles in energy balance and gut barrier function. The paper also noted that fasting interacts with our body's natural daily rhythms and can influence immune responses through these microbial changes. Finally, it suggested that incorporating dietary fiber and prebiotics could further enhance these positive effects.

Dietary takeaway

While intermittent fasting is gaining popularity, this review suggests that focusing on a diet rich in fiber, found in fruits, vegetables, and whole grains, could be a valuable strategy to support a healthy gut microbiome. These fiber-rich foods provide prebiotics that nourish beneficial gut bacteria, potentially enhancing the metabolic and immune benefits discussed. Remember, this is a review of existing research, and individual studies, even when summarized, don't provide definitive proof for everyone.

Abstract

Intermittent fasting (IF) has gained increasing attention as a dietary strategy to improve metabolic health and prevent cardiometabolic disorders. Accumulating evidence suggests that modulation of the gut microbiota may represent one of the mechanisms underlying the physiological benefits of IF. This review summarizes the current knowledge on the mechanisms by which IF modulates gut microbial ecology and how these changes influence host metabolic and immune functions. We examine the effects of IF on gut microbiota diversity and composition, highlighting shifts in key microbial taxa associated with metabolic regulation. In addition, we discuss how fasting-induced microbial remodeling affects microbiota-derived metabolites, including short-chain fatty acids and bile acids, which play central roles in energy homeostasis, intestinal barrier integrity, and inflammatory signaling. Increasing evidence indicates that IF interacts with circadian rhythms, influencing both microbial oscillations and host metabolic pathways that coordinate nutrient sensing and energy metabolism. Furthermore, we explore the bidirectional crosstalk between the gut microbiota and the intestinal immune system, emphasizing that fasting-driven microbial changes may modulate inflammatory responses, epithelial barrier function, and immune cell activity. Finally, we discuss nutritional strategies that may enhance the beneficial effects of IF, including the incorporation of prebiotics, dietary fiber, and probiotic supplementation, to promote microbial diversity and functional resilience. Collectively, these findings support a model in which IF acts as a key modulator of the gut microbiota-immune-metabolic axis. Future integrative studies combining gut microbiome, metabolomic, and immunological approaches are needed to better understand these interactions and optimize microbiota-targeted dietary interventions.

View on PubMed →DOI: 10.3390/nu18162657