Introduction Although already of high prevalence, overweight and obesity are still increasing in many parts of the world. The objective was to evaluate the secular trend of overweight and obesity in adolescents of high socioeconomic level over a decade in a developed city of Brazil.

Method Two cross-sectional studies included 2825 students (1348 evaluated in 2001 and 1477 evaluated in 2010) of both genders and ages 7 to 18 years, from private schools in Campinas, SP, Brazil. The schools were randomly chosen. The first sample included 663 boys and 685 girls and the second included 709 boys and 763 girls. The BMI/age cut-off points of the Who Growth Standards 2007 were considered in the nutritional diagnosis: overweight >+1SD and obesity >+2SD. This study was approved by the Research Ethics Committee of PUC-Campinas (protocol no. 693/09).

Results The percentage of overweight adolescents (23%) remained stable during this period. Obesity increased from 10% (95% CI 8.4 to 11.6) in 2001 to 15% (95% CI 13.2 to 16.8) in 2010. Overweight and obesity were greater in boys than girls in both samples. Overweight and obesity were respectively 25% and 15% (95% CI 12.3 to 17.7) in 2001, 23% and 19% (95% CI 16.1 to 21.9) in 2010 for boys, and 22% and 6% (95% CI 5.1 to 6.9) in 2001 and 22% and 10% (95% CI 7.9 to 12.1) in 2010 for girls.

Conclusion These data show that obesity are increasing and point to the need for immediate interventions in order to prevent this trend.