Body Mass Index and Prevalence of Obesity in Brazilian Adult Women: Temporal Comparison of Repeated Population-Based Cross-Sectional Surveys.

Background: Obesity is a complex multifactorial disease that has been associated with higher morbidity and mortality. Objectives: This study aimed to compare changes in body mass index (BMI) and obesity prevalence between two cross-sectional samples of Brazilian women. Furthermore, retrospective assessments of lifetime body weight changes were explored. Methods: Two independent population-based cross-sectional surveys were conducted in 2003 (first survey) and 2015 (second survey) with women living in the urban area city in southern Brazil. Both surveys had a similar design and included 981 women aged 20-60 years. Mean BMI and the presence of obesity (BMI ≥ 30 kg/m²) were estimated. Additionally, lifetime body weight change was obtained for the retrospective longitudinal assessment. Results: After 12 years, there was a significant increase from 25.9 ± 5.3 kg/m² to 28.1 ± 6.2 kg/m² in mean BMI. Between 2003 and 2015, the prevalence of obesity increased by 73% (18.0%; 95% CI: 15.8-20.6 vs. 31.2%; 95% CI: 28.3-34.1; p < 0.001). The means of estimated cumulative body weight gain from 15 to 50 years were 15.2 kg (95% CI: 13.3-17.1) and 17.2 kg (95% CI: 15.5-18.9) in 2003 and 2015, respectively; the greater cumulative difference between the two periods was observed at 40 years of age (3.3 kg). Conclusions: There was a significant increase in the mean BMI and prevalence of obesity between 2003 and 2015. Moreover, women experienced higher body weight gain during their lives in both survey periods, mainly in early adulthood.