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Objective: To analyse the dietary intake of Brazilian adolescents and investigate its association with sociodemographic factors as well as health-risk and health-protective behaviours., Design: Cross-sectional study., Setting: The study was based on data supplied by the National Survey of Schoolchildren's Health (2012) on sociodemographic factors, dietary intake and health-risk and health-protective behaviours of schoolchildren in Brazil. A nutritional scale was elaborated combining markers of healthy and unhealthy diets. Poisson regression analysis was applied to investigate the association between the sociodemographic factors and regular intake (≥5 times/week) of selected foods; linear regression analysis was applied to investigate the association of sociodemographic and behavioural factors with nutritional scale score., Subjects: A total of 109 104 adolescents attending the ninth year of education at 2842 schools in Brazil., Results: Fewer than 30 % of the adolescents consumed raw or cooked vegetables on a regular basis, whereas more than one-third reported regular intake of sweets, soft drinks and sweet biscuits. Adolescents from the southern area and the oldest ones were those most exposed to inadequate dietary intake. The nutritional scale average score was higher in the students attending public school and exhibited a positive correlation with protective behaviours, such as being physically active, having meals with parents and eating breakfast, and a negative correlation with risk behaviours such as eating while studying or watching television and having smoked, drunk alcohol or used other drugs in the previous 30 d., Conclusions: The results indicate an association between undesirable nutritional habits and other risk behaviours among Brazilian adolescents.

Background: Physical activity in adolescents is associated with short- and long-term health benefits. Physical activity can occur in various domains and is influenced by a complex network of factors. The aims of this study are 1) to describe the physical activity of Brazilian adolescents in physical education classes, during leisure time, and during active commuting and 2) to investigate the socio-demographic and behavioral factors associated with physical activity., Methods: The representative sample included 109,104 Brazilian students in the final year of elementary school from 2,842 schools. The weekly frequency and duration of physical activity were assessed. A variety of socio-demographic and behavioral factors were studied. A multiple Poisson regression analysis was used to test for associations between physical activity and the socio-demographic and behavioral variables., Results: Most of the students (97.0%) engaged in physical activity in at least one of the domains studied, especially physical education at school (81.7%) and leisure time physical activity (67.5%). However, only 29% of the adolescents reached the recommended level of physical activity. Among the adolescents who reached the minimum recommended time for physical activity, the various domains contributed the following proportions to total physical activity: leisure time physical activity (PR 12.5; 95% CI 11.17-13.97), active commuting (PR 1.63; 95% CI 1.59-1.67), and physical education at school (PR 1.36; 95% CI 1.29-1.44). The weekly frequency of all activities was greater among boys than among girls. Moreover, nearly two-thirds (61.8%) of students spent more than two hours per day engaging in sedentary behaviors; the prevalence of sedentary behaviors was similar between boys and girls (59.0 and 64.5%, respectively).Total level of physical activity, leisure time physical activity, and active commuting were associated with higher nutritional scores., Conclusions: Physical activity is important in any health promotion program. Therefore, it is necessary to invest in policies and interagency initiatives that promote all domains and to ensure that the general population helps determine the scope and design of such policies.

Objective: To identify the association of individual and school environment factors with overweight among adolescents., Design: Cross-sectional study. Sociodemographic and behavioural information was collected using an anonymous self-administered questionnaire. Indicators on human and physical resources of the schools were based on information collected in interviews with school principals. Overweight was defined based on the BMI Z-score for age and sex recommended by WHO. Logistic regression models were used for statistical analysis., Setting: Rio de Janeiro, Brazil., Subjects: By means of a two-stage (classrooms and students) probabilistic sampling, subjects comprised 1632 students enrolled in the last year of primary education of the municipal public school network, stratified by city region., Results: The mean prevalence of overweight at schools was 17·2%, ranging from 0% to 50%. Adolescents more likely to be overweight were those who attended schools without knives and forks or ceramic/glass plates for students in the school refectory (prevalence odds ratio (POR) = 1·40; P = 0·04), those whose head of household had completed between 8 and 10 years of schooling (POR = 1·46; P = 0·03), those who did not live with both parents (POR = 1·24; P = 0·06) and those who had not practised physical activity outside school on at least 1 d in the 7 d before the study (POR = 1·56; P = 0·04)., Conclusions: Sociodemographic and behavioural variables of adolescents and school characteristics were associated with overweight, confirming individual and context effects on this health disorder. Studies such as the present one, identifying variables in context, may support actions to prevent overweight among adolescents.

Objective: To assess time trends in the contribution of processed foods to food purchases made by Brazilian households and to explore the potential impact on the overall quality of the diet., Design: Application of a new classification of foodstuffs based on extent and purpose of food processing to data collected by comparable probabilistic household budget surveys. The classification assigns foodstuffs to the following groups: unprocessed/minimally processed foods (Group 1); processed culinary ingredients (Group 2); or ultra-processed ready-to-eat or ready-to-heat food products (Group 3)., Setting: Eleven metropolitan areas of Brazil., Subjects: Households; n 13,611 in 1987-8, n 16,014 in 1995-5 and n 13,848 in 2002-3., Results: Over the last three decades, the household consumption of Group 1 and Group 2 foods has been steadily replaced by consumption of Group 3 ultra-processed food products, both overall and in lower- and upper-income groups. In the 2002-3 survey, Group 3 items represented more than one-quarter of total energy (more than one-third for higher-income households). The overall nutrient profile of Group 3 items, compared with that of Group 1 and Group 2 items, revealed more added sugar, more saturated fat, more sodium, less fibre and much higher energy density., Conclusions: The high energy density and the unfavourable nutrition profiling of Group 3 food products, and also their potential harmful effects on eating and drinking behaviours, indicate that governments and health authorities should use all possible methods, including legislation and statutory regulation, to halt and reverse the replacement of minimally processed foods and processed culinary ingredients by ultra-processed food products.

Based on three comparable surveys conducted in the last quarter of the 20th century in the most heavily populated areas of Brazil, a substantial change was observed in the secular trend towards obesity based on levels of schooling in the population. While during the first period (1975-1989) there was an increasing risk of obesity for all levels of schooling, with the greatest upward trend for men and women with more schooling, during the second period (1989-1997) the increase in obesity was the greatest for individuals with no schooling, along with a stabilization or even decrease in this condition among groups of females with medium or higher education. As a result of the upward trend, the positive relationship decreased between schooling and risk of obesity in men, and the inverse relationship already observed in the female population was further increased. The main potential implications of these findings are for public health.