This study explores what happens in the body and wellbeing during and after a period of long-term fasting. At the Buchinger Wilhelmi Clinic, participants follow a medically supervised fasting program lasting five or more days, followed by a structured food reintroduction phase. The study observes participants over time to better understand how fasting and the return to eating affect weight, metabolism, nutrition habits, and overall well-being. All participants will complete online questionnaires during the fasting phase and for up to three months afterward. These surveys help track changes in lifestyle, mood, and health. In addition during the first two weeks after fasting ends participants wear a continuous glucose monitor (CGM) to track blood sugar levels in real time, use a mobile app to document meals with photos, and perform simple at-home blood tests using dried blood spot (DBS) kits. By combining digital tools with personal reports and at home tests, the study aims to gain a clearer picture of how the body adapts after a prolonged fast. The goal is to better understand the short- and medium-term effects of extended fasting on metabolism, diet, and well-being-and to provide practical guidance for those interested in fasting as a health practice.
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Body weight
Timeframe: From the fasting start until 3 month after fasting