Fasting Conditions

Type of Study: Clinical Trial Goal: The goal of this clinical trial is to investigate whether combining the Buchinger Wilhelmi prolonged fasting program with a structured exercise program can improve physical fitness, body composition, cardiometabolic health, sleep quality, and health-related quality of life. The study will also investigate metabolic responses to prolonged fasting and whether these responses are influenced by exercise. Participant Population/Health Conditions: The study will involve adults attending the Buchinger Wilhelmi Clinic who undergo the prolonged fasting program and meet the study eligibility criteria. Main Questions: * Does structured exercise performed before and/or during prolonged fasting enhance its effects on physical fitness, body composition, and cardiometabolic health? * Does structured exercise improve sleep quality and health-related quality of life during prolonged fasting? Participants Will: * Undergo the Buchinger Wilhelmi prolonged fasting program. * Choose whether to complete an online exercise program before the clinical stay and/or a supervised exercise program during fasting. * Undergo physiological, physical fitness, and body composition assessments before and after the intervention. * Provide blood samples to assess cardiometabolic and metabolic responses. * Complete assessments of sleep and health-related quality of life. Comparison Groups: Researchers will compare the four study conditions to determine whether structured exercise performed before and/or during prolonged fasting enhances the physiological, metabolic, and functional effects of the Buchinger Wilhelmi fasting program.