The objective of this study is to obtain reliable data from recent studies concerned with obesity and its determinants in Portuguese children and adolescents. We searched in Medline/PubMed published data on overweight and obesity in Portuguese children and adolescents; search terms included “Portugal”, “overweight”, “obesity”, “children” and “adolescents”. We also conducted limited hand-searching of additional studies from PhD theses and other academic theses that addressed overweight or obesity in children and adolescents. Studies that considered body mass index based on self-reported weight and height were excluded. We identified 15 studies that reported overweight and obesity in children and adolescents in Portugal, but 1 study was excluded because it included self-reported weight and height. The International Task Force Recommendation (IOTF) using Cole cut-offs was the most used criterion to estimate overweight and obesity, followed by the age- and sex-specific BMI reference percentiles developed by the United States Centers for Disease Control and Prevention (CDC). The range of ages in these studies was between 2 and 15 years. There were some variations in the prevalence of overweight and obesity among studies and different regions. In children between 3 and 5 years of age, one study reported that overweight reached 13.6% in boys and 20.4% in girls, and obesity varied between 6.5% and 6.9%, respectively, in boys and girls. Between 6 and 10 years of age (using the IOTF definition), in boys, the prevalence of overweight varied from 14.7 to 30.5% and obesity from 5.3 to 13.2%; in girls, overweight values ranged from 16.5 to 29.1% and obesity from 6.4 to 12.6%. One study evaluated only adolescents that were born in 1990 (ages varied between 13 and 14 years) and reported both prevalences of overweight and obesity; the applied method was CDC criteria; in boys, the percentage of overweight was 16.9%, and obesity prevalence was 11.3%; in girls, overweight was 16.0% and the percentage of obese was 9.2%. The prevalence of overweight and obesity in Portuguese children and adolescents may be considered as alarming, and early intervention to prevent obesity is needed.