In a follow-up study overweight and obese patients fasting according to Buchinger (modified) and a control group treated by a weight reduction diet in the context of an inpatient naturopathic complex treatment were compared using a questionnaire developed for a standardized phone interview 6.8 ± 1.1 years after inpatient treatment. During the inpatient treatment the fasting patients significantly more body weight, but at the time of the interview significantly more weight was gained again. 10.7% of the fasting patients and 31.9% of the control group lowered their weight at least 5% of their initial weight up to the interview. 42% of the fasting and 74% of the control group persistently changed their diet. The control group followed a significantly higher number of trained nutritional aspects. 21% of the fasting and 40% of the control group increased their leisure activity permanently. Continued improvement in quality of life was achieved by 16% of the fasting patients and 28% of the control group. The fasting therapy, carried out as part of the inpatient naturopathic complex treatment, turned out to be less suitable for the treatment of overweight and obesity compared to standard therapy. One likely determinant is the minor poststationary lifestyle modification.