What factors explain the increase in obesity in Brazil? An ecological analysis of contextual and behavioural components.

OBJECTIVES: It has been suggested that contextual factors may be related to obesity; however, they have not yet been widely investigated. The main objective of this ecological time-series study was to analyse factors associated with the increase in obesity in the adult and elderly population in Brazil from 2006 to 2020. STUDY DESIGN: This is an ecological time-series study. Data were collected by the Surveillance System for Risk and Protection Factors for Chronic Diseases by Telephone Survey (VIGITEL), the main health survey in Brazil. METHODS: The outcome was the annual obesity growth rate (in percentage points). Independent variables were behavioural and contextual factors. Data analysis was performed using Prais-Winsten regression for temporal analyses, and Spearman correlation and crude and adjusted linear regression (beta and 95% confidence intervals [CIs]). RESULTS: The annual obesity growth rate was 0.58 percentage points (p.p.) (95% CI: 0.54; 0.63) per year. Demographic density and the percentage of the population employed showed an inverse association with the growth of obesity. Variables such as Gross Domestic Product (GDP) per capita, Gini coefficient, urbanisation rate, percentage of the population with low level of education and percentage of the population without an income were directly associated with the increase in obesity rates. The variables maintained in the final model explained 81% of the growth in obesity in Brazil over the last 15 years (2006-2020). CONCLUSIONS: The growth of obesity in Brazil was mostly explained by contextual factors, especially those of a socio-economic nature. Therefore, interventions to mitigate the increase in obesity must go beyond behavioural factors.

Is the number of siblings associated with dietary patterns in adolescents? The 1993 birth cohort of Pelotas (Brazil).

Our study aimed to estimate the association between number of siblings and dietary patterns in adolescents. Prospective longitudinal study was developed using data from the birth cohort of the city of Pelotas, Brazil, which included 5249 participants. At the 18-year-old follow-up, from 4563 individuals located, 4106 were interviewed (follow-up rate 81.3%). Of these, 3751 were included in our principal component analysis of dietary patterns. Regular dietary intake of 45 food groups over the previous year was measured with a food frequency questionnaire. We identified four patterns, which accounted for 40% of the total variance in food group consumption. These were labeled "Protein and fast food", "Fruit and vegetables", "Common Brazilian", and "Sweets, soft drinks, and dairy products". Crude and adjusted analyses of the association between number of siblings and dietary patterns were performed using linear regression. The number of siblings was positively associated with a higher adherence to each dietary pattern, with the exception of the "Common Brazilian" patterns, for which there was no apparent relationship with number of siblings. The findings showed that a greater number of siblings is related to a more diverse diet in the later adolescence, which may predict better nutrient adequacy and health outcomes.

The influence of birth order and number of siblings on adolescent body composition: evidence from a Brazilian birth cohort study.

The aim of this study was to estimate the association between birth order and number of siblings with body composition in adolescents. Data are from a birth cohort study conducted in Pelotas, Brazil. At the age of 18 years, 4563 adolescents were located, of whom 4106 were interviewed (follow-up rate 81.3 %). Of these, 3974 had complete data and were thus included in our analysis. The variables used in the analysis were measured during the perinatal period, or at 11, 15 and/or 18 years of age. Body composition at 18 years was collected by air displacement plethysmography (BOD POD®). Crude and adjusted analyses of the association between birth order and number of siblings with body composition were performed using linear regression. All analyses were stratified by the adolescent sex. The means of BMI, fat mass index and fat-free mass index among adolescents were 23.4 (sd 4.5) kg/m², 6.1 (sd 3.9) kg/m² and 17.3 (sd 2.5) kg/m², respectively. In adjusted models, the total siblings remained inversely associated with fat mass index (ß = - 0.37 z-scores, 95 % CI - 0.52, - 0.23) and BMI in boys (ß = - 0.39 z-scores, 95 % CI - 0.55, - 0.22). Fat-free mass index was related to the total siblings in girls (ß = 0.06 z-scores, 95 % CI - 0.04, 0.17). This research has found that number of total siblings, and not birth order, is related to the fat mass index, fat-free mass index and BMI in adolescents. It suggests the need for early prevention of obesity or fat mass accumulation in only children.