Süleyman ULUPINAR, Serhat ÖZBAY, Deniz BEDİR, Ayşe TÜRKSOY IŞIM, Fatih KIYICI, Hasan Hüseyin YILMAZ, Selim ASAN, Murat TURAN
Archives of Health Science and Research - 2025;12(1):1-6
Objective: Prolonged water-only fasting has garnered significant interest for its potential health benefits, including enhanced metabolic flexibility and cardiovascular improvements. This case study explores the physiological and metabolic responses of a healthy 36-year-old male during a 10-day water-only fast, followed by a structured 5-day refeeding phase. Methods: Key parameters such as heart rate variability (HRV), respiratory quotient (RQ), resting metabolic rate (RMR), oxygen consumption (VO?), and sleep quality were monitored throughout the fasting and refeeding periods. Data col- lection was conducted at the Laboratory of Atatürk University Faculty of Medicine in February 2025. Results: Findings revealed substantial metabolic adaptations, including a decline in RMR from 2040 kcal/day to 1342 kcal/day and a reduction in RQ from 0.89 to 0.74 by fasting day 7, indicating a shift from carbohydrate to fat oxidation. Cardiovascular parameters, including blood pressure and heart rate, remained stable, while sleep patterns exhibited notable variability, with a marked reduction in deep sleep after the third day of fasting. During the refeeding phase, metabolic and physiological parameters progressively returned to baseline levels, underscoring the importance of dietary reintroduction in restoring homeostasis. Conclusion: This study highlights the dynamic interplay between metabolic rate, substrate utilization, and cardio- vascular stability during prolonged fasting and refeeding. While the findings align with existing literature, the results emphasize the individuality of fasting responses and the necessity for medical supervision. These insights contribute to the growing body of evidence supporting water-only fasting as a potentially safe and effective intervention for met- abolic health, warranting further investigation in diverse populations.
