Therapeutic fasting has been used for many decades in naturopathy and integrative medicine clinically successfully in the treatment of chronic diseases and pain syndromes. In particular, fasting therapy is used for chronic rheumatic, inflammatory, and metabolic diseases with increasing patient demand in specialized clinical facilities (fasting clinics).~Within the various historically developed forms of fasting, the fasting program according to the Buchinger Wilhelmi method has established itself worldwide as the most frequently applied method. This involves a subtotal caloric restriction with a daily caloric intake (200-400kcal/day) in the form of liquid components over a defined period of at least 10 days, accompanied by supporting measures of a health-promoting lifestyle program with elements such as exercise therapy, manual procedures, stress reduction and hydro-balneotherapy.~In early randomized studies and a systematic review, the effectiveness of inpatient fasting therapy for patients with rheumatoid arthritis was proven with 1a evidence. For the other indications, there is mainly empirical evidence or data from observation or prospective uncontrolled studies. In recent years, extensive basic science research activity has developed in the area of caloric restriction and intermittent fasting. In this context, a large number of favorable animal experimental findings have been demonstrated by defined fasting periods, including reductions in insulin, IGF-1, increases in adiponectins, insulin sensitivity, neurotrophic factors, and, over longer observation periods, a decrease in the incidence of cardiovascular, inflammatory, and metabolic, and more recently oncological diseases in a wide variety of animal species.~Numerous experimental studies have demonstrated that fasting or total or subtotal caloric restriction is a potent inducer of cellular autophagy. For autophagy, numerous beneficial effects on chronic diseases or disease defense functions have now been experimentally documented and also hypothesized for humans, including neurodegenerative and metabolic diseases, but also acute infections and inflammatory diseases. Unclear to date is the kinetics of the autophagy enhancing effect of fasting. In theoretical transfer from animal experimental data, an increase is postulated between 12 and 36h of fasting and possibly a decrease after several days.~Against this background, autophagy will now be investigated for the first time in blood samples from fasting healthy and diseased individuals in an exploratory clinical study.
Autophagy is considered one of the key molecular mechanisms for the broad preventive and therapeutic effects of periodic fasting. While it is generally known that fasting induces autophagy, there are no human studies that focus on the size and temporal kinetics of autophagy and its association with fasting specific signaling pathways. The kinetics of autophagy in patients with chronic diseases will now be compared with the kinetics of autophagy in healthy subjects, who both fast according to the same scheme; and further changes in metabolic and inflammatory parameters will be investigated.