The outpatient lifestyle interventions Obeldicks (for 8- to 16-year-old obese children; 1-year intervention), Obeldicks Light (for 8- to 16-year-old overweight children; 6-month intervention), and Obeldicks Mini (for 4- to 7-year-old obese children; 1-year intervention) are based on nutrition education, physical activity, behavior therapy, and individual psychological care. Only 17% dropped out of the intervention, and 79% of the more than 1,000 participants reduced their degree of overweight. The mean SDS-BMI reduction was 0.4 (~1.5-2 kg/m(2) BMI reduction) and was associated with a significant improvement of hypertension, dyslipidemia, and disturbed glucose metabolism in the participants compared to an untreated control group. This efficiency was also proven by a multicenter randomized controlled trial. Furthermore, the quality of life of the participants improved significantly. Even 4 years after the end of intervention, the achieved weight loss was sustained. Training manuals and training seminars for professionals assist in the implementation of these lifestyle interventions at further locations.