Could Fasting Increase Life Expectancy?

The Gut Microbiome, Fasting, and Longevity: A Holistic Perspective


The gut microbiome, fasting, and longevity are interconnected in fascinating ways, offering profound insights into human health and well-being. The gut microbiome, a complex ecosystem of trillions of microorganisms residing in the gastrointestinal tract, plays a pivotal role in various aspects of health, including immune function, metabolism, and even longevity. Fasting, a practice of abstaining from food for defined periods, has gained attention for its potential to influence the gut microbiome and promote longevity. This article delves into the relationship between these three aspects and their implications for human health and longevity.

The Gut Microbiome

The gut microbiome refers to the diverse community of microorganisms inhabiting the digestive system. This ecosystem consists of bacteria, viruses, fungi, and other microorganisms that play a crucial role in nutrient digestion, immune regulation, and the synthesis of essential compounds. The gut microbiome’s composition is influenced by a myriad of factors, including genetics, diet, and environmental exposures.

Research indicates that a balanced and diverse gut microbiome is essential for health. A healthy gut microbiome is associated with:

  1. Enhanced Immune Function: Gut bacteria interact with the immune system, helping to distinguish between harmful pathogens and beneficial microorganisms. A well-balanced microbiome can strengthen the body’s defense mechanisms.
  2. Nutrient Metabolism: The gut microbiome assists in the digestion of dietary fiber, producing short-chain fatty acids that serve as an energy source and have anti-inflammatory effects.
  3. Metabolic Health: Dysbiosis, an imbalance in the gut microbiome, has been linked to obesity and metabolic disorders such as type 2 diabetes.
  4. Brain-Gut Axis: Emerging research highlights the gut-brain connection, suggesting that the gut microbiome can influence mood, cognition, and mental health.
The brain-gut connection is increasingly recognised in science.

Fasting and the Gut Microbiome

Fasting, the voluntary abstention from food for defined periods, can profoundly affect the gut microbiome. The effects of fasting on the gut microbiome can be summarised as follows:

  1. Microbiome Diversity: Fasting can lead to an increased diversity of gut bacteria. A more diverse gut microbiome is associated with better health outcomes and is linked to improved immune function.
  2. Autophagy: Fasting induces autophagy, a cellular recycling process that removes damaged cells and cellular components. This process can help eliminate harmful bacteria from the gut and promote a healthier microbiome.
  3. Changes in Microbial Composition: Fasting can lead to shifts in the relative abundance of various microbial species. Certain fasting protocols, such as intermittent fasting, may promote the growth of beneficial bacteria, including those associated with improved metabolic health.
  4. Enhanced Gut Barrier Function: Fasting may help improve the gut’s barrier function, reducing the risk of bacterial translocation and inflammation.

Longevity and the Gut Microbiome

The gut microbiome’s influence on longevity is an emerging area of research. There is evidence to suggest that a healthy gut microbiome can promote longevity through several mechanisms:

  1. Inflammation: A balanced gut microbiome can help mitigate chronic inflammation, a key driver of aging and age-related diseases.
  2. Immune Function: A well-regulated gut microbiome can support a robust immune system, which is crucial for defending against infections and maintaining overall health in old age.
  3. Metabolism: The gut microbiome influences metabolic health, and improved metabolic function is associated with increased lifespan.
  4. Nutrient Absorption: A healthy gut microbiome can enhance the absorption of essential nutrients, potentially increasing the body’s resilience to age-related declines.
Chronic inflammation is a known cause of disease.

Scientific Evidence

Several studies support the connection between the gut microbiome, fasting, and longevity. For example, a 2017 study published in the journal “Cell Metabolism” demonstrated that fasting mimicking diets (FMDs) could promote longevity in mice by improving the gut microbiome and reducing markers of aging. Similarly, a 2020 study in “Nature Communications” explored the effects of time-restricted feeding on the gut microbiome and found that this approach improved metabolic health and longevity in mice.

The potential link between the gut microbiome and human longevity is further reinforced by observational studies that have shown associations between the composition of the gut microbiome and age-related diseases like cardiovascular disease, neurodegenerative conditions, and metabolic disorders.

Ancient humans were thought to go through cycles of fasting, then foraging, then feasting, as they would be going numerous hours before catching each prey. Fasting between meals, therefore, appears to have been the norm throughout the development of the homo sapien species for thorusands of years.

Ancient humans were thought to eat meat and then spend hours to days fasting and foraging berries, roots & leafy vegetation.


The gut microbiome, fasting, and longevity are intricately connected, offering valuable insights into the maintenance of health and well-being. A healthy gut microbiome is essential for immune function, metabolism, and overall health, while fasting has the potential to positively influence the gut microbiome. Together, they may contribute to increased longevity through reduced inflammation, improved metabolic health, and enhanced immune function.

However, it is essential to acknowledge that the field of microbiome research is continuously evolving, and there is still much to learn about the precise mechanisms and interplay between these factors. As such, individuals should approach fasting and gut microbiome modulation through seeking guidance from healthcare professionals and considering individual health needs and goals.

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