The world’s largest fasting study, led by Dr. Françoise Wilhelmi de Toledo, the eminent head of the research department at the Buchinger Wilhelmi Clinics, marks a significant milestone in the scientific exploration of fasting as a therapeutic intervention. Located in Überlingen, Germany, and Marbella, Spain, these clinics are renowned for their specialization in periodic fasting, drawing on over seven decades of clinical expertise. Dr. Toledo, who embraced fasting as a personal health practice at the age of 17, spearheaded this groundbreaking research initiated in 2016, which meticulously tracked the fasting journeys of 1,422 participants over periods ranging from four to twenty days.

Introduction to the Largest Fasting Study

The primary objective of this ambitious study was to systematically capture and analyze the wealth of clinical observations accumulated over years of practice at the Buchinger Wilhelmi Clinics. By doing so, the research sought to substantiate the clinics’ longstanding advocacy of fasting as a potent, natural method for addressing a spectrum of diseases. Unique to the fasting program at these clinics is its holistic approach, which integrates medical supervision, community support, and emotional-spiritual nourishment, thereby offering participants a comprehensive fasting experience.

Findings and Implications

The findings from this extensive study are not just voluminous but profoundly illuminating, shedding light on the multifaceted benefits of fasting. Participants reported significant improvements in various health markers, including reductions in body weight, lower cholesterol levels, and enhanced glucose metabolism. Additionally, many observed a marked decrease in inflammation markers, suggesting a potential for fasting to mitigate chronic inflammatory conditions.

Beyond the physical health benefits, the study also highlighted the psychological and emotional gains associated with fasting. Participants frequently cited increased mental clarity, improved emotional well-being, and a deeper sense of spiritual connection during and after their fasting periods. This aligns with the clinic’s three-dimensional approach to fasting, emphasizing the importance of nurturing the mind and spirit alongside the body.

Methodology and Participant Experience

The methodology of the world’s largest fasting study was rigorously designed to ensure both the reliability and validity of its findings. Participants underwent a comprehensive pre-fasting evaluation to assess their baseline health status, followed by continuous medical monitoring throughout their fasting journey. Post-fasting assessments were conducted to document physiological changes, psychological states, and overall well-being.

The participant experience, as detailed in the study, reveals the transformative potential of fasting when conducted in a supportive, medically supervised environment. The communal aspect of fasting at the Buchinger Wilhelmi Clinics, where individuals come together to share their journey, played a crucial role in enhancing the fasting experience, providing both motivation and comfort.


Main Points of Largest Fasting Study:

  • Metabolic Improvements: Significant improvements were observed in metabolic parameters, including weight loss (particularly around the abdomen), reduced blood pressure (both systolic and diastolic), normalized blood sugar levels, and increased ketone bodies in urine, indicating a metabolic shift from a “feeding program” to a “fasting program.”
  • Blood Parameters: There was a reduction in blood lipids, including triglycerides and LDL cholesterol. Liver and kidney functions remained normal, and there was notable recovery in cases of fatty liver.
  • Inflammation and Immune Response: The study documented a decrease in inflammation markers, supporting previous research that inflammation tends to reduce during fasting. Additionally, a reduction in blood cells through autophagy and apoptosis suggested the elimination of aging cells and damaged structures.
  • Post-Fasting Regeneration: Participants were advised to reintroduce food slowly over four to five days post-fasting, a period marked by cell and tissue regeneration, including the rejuvenation of immune cells in the blood, facilitated by the activation of stem cells during fasting.


500 fasting participants
  • Participant Groups

    The study included healthy individuals seeking preventive care and approximately 500 participants with specific conditions, categorized into three groups: those with metabolic issues (e.g., hypertension, Type 2 diabetes), chronic inflammatory diseases (e.g., arthritis, skin problems), and psychological or physical exhaustion (e.g., pre-burnout, depression). An overwhelming 85% reported a significant subjective improvement in their conditions.

    fasting intervention


    The 2020 Buchinger Wilhelmi fasting study, published in PLOS ONE in January 2019, offers compelling evidence of the benefits of fasting, not only for weight management and metabolic health but also for inflammation reduction, immune system regeneration, and overall well-being. Dr. Toledo encourages viewers to explore fasting, emphasizing its feasibility and benefits for adults seeking to rejuvenate their bodies and improve their health.

    Dr. Toledo concludes by advocating for the integration of fasting into regular health routines, highlighting its potential for regeneration and rejuvenation. She assures that fasting can be an enjoyable and beneficial experience, contrary to common misconceptions of hunger and discomfort.

    For those interested in exploring fasting further or seeking guidance, especially if dealing with health issues, professional medical supervision is recommended. The study’s findings underscore fasting’s role in promoting better health practices and its potential as a transformative health strategy.

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