What causes obesity in children and adolescents?

To present the different aspects that may be involved in the genesis and maintenance of obesity in children and adolescents. Narrative review of articles published in the PubMed, Scielo, Lilacs, Scopus and Google Scholar databases, using the search terms: overweight, obesity, pre-conception, prenatal, infants, schoolchildren, children, and adolescents. The search was conducted in studies written in Portuguese, English and Spanish, including narrative, integrative or systematic reviews, meta-analyses, cross-sectional, case-control and cohort studies, published between 2003 and 2023. A total of 598 studies were initially screened and 60 of them, which showed the main biopsychosocial aspects related to greater risks of excessive adiposity in the pediatric age, were included in the review. The data were presented taking into account the incidence of risk factors and their consequences in six periods: pre-conception, pre-natal, infant, preschool, school age, and adolescence. The causal factors described in the scientific literature that have been shown to be related to obesity in childhood and adolescence are presented.