**5. Conclusions**

We can conclude that: (1) Behavioral management in an outpatient specialized clinic for childhood and adolescent obesity can be effective in a significant number of patients and it does not impair lineal growth (privative of this age range and absent in adult patients) that contributes to the effective achievement of BMI reduction. (2) The outcome of the intervention is conditioned by a high attrition rate whose predictive factors should be considered when individually designing the intervention schedule for each patient. (3) BMI reduction is the main determinant of metabolic improvement in children and adolescents with obesity, with the latter being achieved even after a sustained modest BMI reduction and not related to the time spent to achieve weight loss. (4) The best results in BMI reduction are attained during the first year of intervention, particularly in a subset of patients, and can be maintained if follow-up is retained. However, weight can be regained if intervention is stopped prematurely. Consequently, a sufficient follow-up duration must be ensured for these patients.

In summary, our observations support the concept that in a chronic disease such as obesity, long-term, if not life-long, treatment is often required and that the intervention to improve weight and metabolic status must be started at early ages in an attempt to achieve a healthy adulthood.

**Author Contributions:** Conceptualization, G.Á.M.-M. and J.A.; methodology, G.Á.M.-M. and J.A.; software, G.Á.M.-M., J.M.-V.F., A.F.-H. and Á.M.-R.; validation G.Á.M.-M. and J.A.; formal analysis, G.Á.M.-M., J.M.-V.F. and J.A.; investigation, G.Á.M.-M., J.M.-V.F., A.F.-H., Á.M.-R. and J.A.; resources, J.A.; writing—original draft preparation, G.Á.M.-M., J.M.-V.F. and A.F.-H.; writing—review and editing, G.Á.M.-M., J.M.-V.F., A.F.-H., Á.M.-R. and J.A.; visualization, G.Á.M.-M., J.M.-V.F., A.F.-H., Á.M.-R. and J.A.; supervision, G.Á.M.-M. and J.A.; project administration J.A.; funding acquisition, J.A. All authors have read and agreed to the published version of the manuscript.

**Funding:** This work was supported by CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn) and the Instituto de Salud Carlos III, FIS (FIS PI09/91060; FIS PI10/00747; FIS 13/01295 and FIS PI16/00485).

**Institutional Review Board Statement:** The study was conducted according to the guidelines of the Declaration of Helsinki, and approved by Ethics Committee of the Hospital Infantil Universitario Niño Jesús (protocol code R0014/10 and date of approval 29 June 2010).

**Informed Consent Statement:** Informed consent was obtained from parents or guardians of all subjects involved in the study.

**Data Availability Statement:** Data supporting reported results are preserved in investigators' records and available.

**Conflicts of Interest:** The authors declare no conflict of interest.
