CONTEXT:: Despite stabilization of childhood overweight and obesity prevalence, there is a shift toward more severe degrees of obesity, which results in an increasing prevalence of children with morbid obesity. Prior studies demonstrated that lifestyle modification without ongoing treatment has only a modest and not sustainable effect in children with morbid obesity. This suggests that a chronic care model is necessary for long-term effects on weight management and health. OBJECTIVE:: This study aimed to evaluate the effect of an ongoing lifestyle intervention in children with morbid obesity in comparison with children with overweight and obesity. DESIGN AND SETTING:: This was a nonrandomized prospective intervention study with 12- and 24-month followup at the Centre for Overweight Adolescent and Childrenʼs Healthcare. PATIENTS AND INTERVENTION:: Children and adolescents (n = 100 females and 72 males) with overweight, obesity, or morbid obesity were given long-term, outpatient, tailored lifestyle intervention. MAIN OUTCOME MEASURE:: Body mass index (BMI) z score was measured. RESULTS:: In children with morbid obesity, 12- and 24-month interventions resulted in a decrease of BMI z score of −0.13 ± 0.25 (P = .001) and −0.23 ± 0.32 (P = .01) respectively, whereas weight status category improved to obese in 21% and 25% of the children. Cardiovascular risk parameters including serum total cholesterol, low-density lipoprotein cholesterol, glycosylated hemoglobin (HbA1c), and diastolic blood pressure significantly improved after 1-year intervention in the complete group. Most important, BMI z score as well as cardiovascular risk parameters improved to a similar degree in children with overweight, obesity, and morbid obesity. CONCLUSIONS:: Children with overweight, obesity, and morbid obesity benefit equally from an ongoing, outpatient, tailored lifestyle intervention, and demonstrate significant weight loss and improvement of cardiovascular risk parameters.