Background: Overweight and obesity are major risk factors for many chronic diseases in modern societies. A retrospective follow-up study showed an advantage of weight reduction diet (WRD) to fasting therapy  concerning long-term weight loss.
Objective: Prospective comparison of WRD to fasting therapy concerning long-term weight loss. 
Methods: From 08/2007 to 02/2009 90 patients with overweight or obesity were observed with a follow-up period of 6 months, who received either a fasting therapy or a WRD in the context of naturopathic complex in-patient treatment including physical activity.
Results: During the in-patient treatment the fasting patients loosed significantly more weight than the WRD patients, but regained weight during the follow-up, while the weight loss of the WRD patients persisted. 32% of the fasting and 81% of the WRD patients achieved a 5% weight loss after 6 months. Total and LDL-cholesterol were significantly more reduced, controlled eating habits, physical leisure activity and tendentially physical quality of life increased more after 6 months in the WRD group, while the systolic blood pressure declined more in the fasting patients.
Conclusion: Weight loss and improvement of obesity-associated parameters were long-term significantly inferior in fasting patients compared to patients treated with a WRD. The reduced success of the fasting patients is probably caused by the minor lifestyle modification.