Systematic review on obesity in Brazilian adolescents

The purpose of this study was to systematically review the Brazilian literature on the prevalence of obesity and associated factors in adolescents. The literature search was carried out in the electronic databases Pubmed and Bireme, using the keywords: obesity, overweight, BMI, adolescents and Brazil. The following inclusion criteria were considered: Brazilian adolescents, BMI-based obesity estimates, publication until 2007, and adequate methodology. After the examination of titles, abstracts and full texts, 27 papers fulfilled our inclusion criteria. For describing the studies, the following variables were used: type of survey, design, age range, sample size, place of data collection. For evaluating the evidence, the following indicators were used: methods used, independent variables studied, statistical analyses employed, and cut-off used for defining obesity. Most studies used cross-sectional designs (77.7%) and were carried out through home interviews (51.7%). Only one study used a nationally-based sample and three used regional-based samples (Northeast and Southeast). Regardless the design, place, type of survey, age range and cut-off used, the prevalence of obesity tended to be higher in the following groups: adolescents living in the Southeast region, living in urban areas, from high socioeconomic level and from private schools. In terms of behavioral determinants of obesity, the paucity of prospective studies and the difficulties of adequately measuring physical activity and food consumption, make the results less clear. Although the number of studies has increased, it is still necessary to stimulate surveys in the North, Southeast and Mideast regions. Prospective studies are also necessary, in order to evaluate the association between obesity and behavioral exposures