ABSTRACT:

Introduction:

Urbanization and industrialization have contributed to changes in eating patterns, as well as the emergence of sedentary behaviors and reduced physical activity.

Objectives:

To identify and describe the prevalence of eating habits, physical activity and sedentary behavior in Brazilian schoolchildren, and to analyze their association with sociodemographic characteristics.

Methods:

Data from the National Student Health Survey (PeNSE) of 2015 were used. Prevalence rates, prevalence ratios, and 95% confidence intervals (95%CI) were calculated. The analyses were adjusted for age and maternal schooling.

Results:

The majority of adolescents: consumed beans (65.1%) and snacks (52.3%); had more than three days of physical education at school (50.7%); practiced physical activity out of school for more than three days (55.4%); had a sedentary behavior (73.3%); and, had physical activity during 60min/day for less than four days a week (72.7%). In general, girls were more exposed to unhealthy eating habits and sedentary behavior, and a higher socioeconomic level was associated with higher prevalence of the indicators studied. High consumption of unhealthy foods, increased sedentary behavior and reduction in the practice of physical activity.

Conclusion:

An association of unhealthy attitudes with sociodemographic characteristics was observed among schoolchildren. Strategies that focus on reducing these behaviors will contribute to health promotion actions in the school and family environments.

Keywords:
Adolescent; School; Food habits; Physical activity

INTRODUCTION

Important changes in the dietary patterns and physical activity (PA) habits of the world population characterize the food and nutritional transition¹1. Popkin BM, Adair LS, Ng SW. Global nutrition transition and the pandemic of obesity in developing countries. Nutr Rev 2012; 70(1): 3-21. https://doi.org/10.1111/j.1753-4887.2011.00456.x
https://doi.org/https://doi.org/10.1111/... . Urbanization and industrialization contributed to the change in eating patterns²2. Gill M, Feliciano D, Macdiarmid J, Smith P. The environmental impact of nutrition transition in three case study countries. Food Secur 2015; 7: 493-504. https://doi.org/10.1007/s12571-015-0453-x
https://doi.org/https://doi.org/10.1007/... , as well as to the emergence of sedentary behaviors (SB) and the reduction of PA³3. Owen N, Sparling PB, Healy GN, Dunstan DW, Matthews CE. Sedentary behavior: emerging evidence for a new health risk. Mayo Clin Proc 2010; 85(12): 1138-41. https://dx.doi.org/10.4065%2Fmcp.2010.0444
https://doi.org/https://dx.doi.org/10.40... .

Recently, there has been a rapid increase of this transition in developing countries, which are in the process of social, economic and technological changes, generating greater purchasing power and access to industrialized products of low nutritional quality⁴4. Bielemann RM, Motta JVS, Minten GC, Horta BL, Gigante DP. Consumption of ultra-processed foods and their impact on the diet of young adults. Rev Saúde Pública 2015; 49: 28. https://doi.org/10.1590/s0034-8910.2015049005572
https://doi.org/https://doi.org/10.1590/... ^,55. Monteiro CA, Cannon G, Moubarac JC, Levy RB, Louzada MLC, Jaime PC. The UN Decade of Nutrition, the NOVA food classification and the trouble with ultra-processing. Public Health Nutr 2018; 21(1): 5-17. https://doi.org/10.1017/S1368980017000234
https://doi.org/https://doi.org/10.1017/... .

In our country, the eating habits of adolescents have been characterized by the high consumption of ultra-processed foods (UPF)⁶6. Monteiro CA, Moubarac JC, Cannon G, Ng SW, Popkin B. Ultra-processed products are becoming dominant in the global food system. Obes Rev 2013; 14(Supl. 2): 21-8. https://doi.org/10.1111/obr.12107
https://doi.org/https://doi.org/10.1111/... that are rich in fats, sugar and sodium, and by the low consumption of fruits and vegetables⁷7. Rauber F, Campagnolo P, Hoffman D, Vitolo M. Consumption of ultra-processed food products and its effects on children’s lipid profiles: a longitudinal study. Nutr Metab Cardiovasc Dis 2015; 25(1): 116-22. https://doi.org/10.1016/j.numecd.2014.08.001
https://doi.org/https://doi.org/10.1016/... ^,88. Pereira TS, Pereira RC, Angelis-Pereira MC. Influência de intervenções educativas no conhecimento sobre alimentação e nutrição de adolescentes de uma escola pública. Ciên Saúde Colet 2017; 22(2): 427-35. http://dx.doi.org/10.1590/1413-81232017222.16582015
https://doi.org/http://dx.doi.org/10.159... ^,99. Howe AS, Black KE, Wong JE, Parnel WR, Skidmore PML. Dieting status influences associations between dietary patterns and body composition in adolescents: a cross-sectional study. Nutr J 2013; 12: 51. https://doi.org/10.1186/1475-2891-12-51
https://doi.org/https://doi.org/10.1186/... ^,1010. Tavares LF, Castro IRR, Levy RB, Cardoso LO, Passos MD, Brito FSB. Validade relativa de indicadores de práticas alimentares da Pesquisa Nacional de Saúde do Escolar entre adolescentes do Rio de Janeiro, Brasil. Cad Saúde Pública 2014; 30(5): 1029-41. http://dx.doi.org/10.1590/0102-311X00000413
https://doi.org/http://dx.doi.org/10.159... ^,1111. Monteiro CA, Cannon G. The impact of transnational “big food” companies on the South: a view from Brazil. PLoS Med 2012; 9(7): e1001252. https://dx.doi.org/10.1371%2Fjournal.pmed.1001252
https://doi.org/https://dx.doi.org/10.13... . In middle-income countries, such as Brazil, UPF consumption is growing rapidly⁶6. Monteiro CA, Moubarac JC, Cannon G, Ng SW, Popkin B. Ultra-processed products are becoming dominant in the global food system. Obes Rev 2013; 14(Supl. 2): 21-8. https://doi.org/10.1111/obr.12107
https://doi.org/https://doi.org/10.1111/... . Examples of these products include sandwich cookies, packaged snacks, soft drinks, instant noodles, among others⁵5. Monteiro CA, Cannon G, Moubarac JC, Levy RB, Louzada MLC, Jaime PC. The UN Decade of Nutrition, the NOVA food classification and the trouble with ultra-processing. Public Health Nutr 2018; 21(1): 5-17. https://doi.org/10.1017/S1368980017000234
https://doi.org/https://doi.org/10.1017/... .

Concomitantly, among adolescents, the time spent in SB with little movement and generally in a sitting or reclined position having an energy expenditure of less than 1.5 MET, such as watching television and using video games and computers, has also grown over time¹²12. Moreno LA, Gottrand F, Huybrechts I, Ruiz JR, González-Gross M, DeHenauw S, et al. Nutrition and lifestyle in european adolescents: the HELENA (Healthy Lifestyle in Europe by Nutrition in Adolescence) study. Adv Nutr 2014; 5(5): 615S-23S. https://doi.org/10.3945/an.113.005678
https://doi.org/https://doi.org/10.3945/... ^,1313. Costigan SA, Barnett L, Plotnikoff RC, Lubans DR. The health indicators associated with screen-based sedentary behavior among adolescent girls: a systematic review. J Adolesc Health 2013; 52(4): 382-92. https://doi.org/10.1016/j.jadohealth.2012.07.018
https://doi.org/https://doi.org/10.1016/... ^,1414. Pate RR, O’Neill JR, Lobelo F. The evolving definition of “sedentary”. Exerc Sport Sci Rev 2008; 36(4): 173-8. https://doi.org/10.1097/JES.0b013e3181877d1a
https://doi.org/https://doi.org/10.1097/... . The habit of sitting for longer times is associated with a series of unfavorable health outcomes¹³13. Costigan SA, Barnett L, Plotnikoff RC, Lubans DR. The health indicators associated with screen-based sedentary behavior among adolescent girls: a systematic review. J Adolesc Health 2013; 52(4): 382-92. https://doi.org/10.1016/j.jadohealth.2012.07.018
https://doi.org/https://doi.org/10.1016/... , including obesity³3. Owen N, Sparling PB, Healy GN, Dunstan DW, Matthews CE. Sedentary behavior: emerging evidence for a new health risk. Mayo Clin Proc 2010; 85(12): 1138-41. https://dx.doi.org/10.4065%2Fmcp.2010.0444
https://doi.org/https://dx.doi.org/10.40... , and can lead to greater consumption of UPF¹³13. Costigan SA, Barnett L, Plotnikoff RC, Lubans DR. The health indicators associated with screen-based sedentary behavior among adolescent girls: a systematic review. J Adolesc Health 2013; 52(4): 382-92. https://doi.org/10.1016/j.jadohealth.2012.07.018
https://doi.org/https://doi.org/10.1016/... due to the convenience of ingesting these products, since they are purchased in packages, ready to eat or to warm up⁵5. Monteiro CA, Cannon G, Moubarac JC, Levy RB, Louzada MLC, Jaime PC. The UN Decade of Nutrition, the NOVA food classification and the trouble with ultra-processing. Public Health Nutr 2018; 21(1): 5-17. https://doi.org/10.1017/S1368980017000234
https://doi.org/https://doi.org/10.1017/... .

Childhood and adolescence are particularly relevant times for the study of SB, as it is characterized by marked physical and mental changes¹⁵15. Alberga AS, Sigal RJ, Goldfield G, Prud’homme D, Kenny GP. Overweight and obese teenagers: why is adolescence a critical period? Pediatr Obes 2012; 7(4): 261-73. https://doi.org/10.1111/j.2047-6310.2011.00046.x
https://doi.org/https://doi.org/10.1111/... . In this sense, there is evidence that SB has a direct impact on health outcomes, such as obesity, metabolic syndrome and cardiovascular diseases¹⁶16. Ferreira RW, Rombaldi AJ, Ricardo LIC, Hallal PC, Azevedo MR. Prevalência de comportamento sedentário de escolares e fatores associados. Rev Paul Pediat 2016; 34(1): 56-63. http://dx.doi.org/10.1016/j.rppede.2015.09.002
https://doi.org/http://dx.doi.org/10.101... ^,1717. Boulos R, Vikre EK, Oppenheimer S, Chang H, Kanarek RB. ObesiTV: how television is influencing the obesity epidemic. Physiol Behav 2012; 107(1): 146-53. https://doi.org/10.1016/j.physbeh.2012.05.022
https://doi.org/https://doi.org/10.1016/... , also having been described as related to reductions in life expectancy¹⁸18. Rezende LF, Rodrigues Lopes M, Rey-López JP, Matsudo VK, Luiz Odo C. Sedentary behavior and health outcomes: an overview of systematic reviews. PLoS One 2014; 9(8): e105620. https://doi.org/10.1371/journal.pone.0105620
https://doi.org/https://doi.org/10.1371/... ^,1919. World Health Organization. Diet, nutrition and the prevention of chronic diseases. Genebra: World Health Organization; 2003. (WHO Technical Report Series, 916)..

Thus, insufficient levels of PA practice can also cause damage to health and well-being and increase the risk of cardiovascular disease, high blood pressure, diabetes, certain types of cancer, obesity and early mortality²⁰20. Silva DAS, Silva RJS. Associação entre prática de atividade física com consumo de frutas, verduras e legumes em adolescentes do Nordeste do Brasil. Rev Paul Pediatr 2015; 33(2): 167-73. https://doi.org/10.1016/j.rpped.2014.09.003
https://doi.org/https://doi.org/10.1016/... . Clinical and epidemiological studies have reported that people with insufficient levels of PA are more affected by depression and anxiety²¹21. Brown DR, Carroll DD, Workman LM, Carlson SA, Brown DW. Physical activity and health-related quality of life: US adults with and without limitations. Qual Life Res 2014; 23(10): 2673-80. https://doi.org/10.1007/s11136-014-0739-z
https://doi.org/https://doi.org/10.1007/... .

Despite having evidence that PA can act to prevent diseases and promote quality of life, a large population remains exposed to insufficient levels of PA practice. In Brazil, for example, data from the National School Health Survey (PeNSE) identified that 56.9% of Brazilian students in the 9^th grade of elementary school did not meet the recommendations for PA practice (≥ 300 minutes per week)²²22. Malta DC, Silva MMA, Albuquerque GM, Lima CM, Cavalcante T, Jaime PC, et al. A implementação das prioridades da Política Nacional de Promoção da Saúde, um balanço, 2006 a 2014. Ciên Saúde Colet 2014; 19(11): 4301-12. http://dx.doi.org/10.1590/1413-812320141911.07732014
https://doi.org/http://dx.doi.org/10.159... . Recent research has shown that more than 70% of adolescents from different countries do not reach the recommendations for PA practice²³23. Hallal PC, Andersen LB, Bull FC, Guthold R, Haskell W, Ekelund U. Global physical activity levels: surveillance progress, pitfalls, and prospects. Lancet 2012; 380(9838): 247-57. https://doi.org/10.1016/S0140-6736(12)60646-1
https://doi.org/https://doi.org/10.1016/... .

Thus, the objectives of this study were to identify and describe the prevalence of eating habits, PA practice and sedentary behavior in Brazilian schoolchildren and to analyze their association with sociodemographic characteristics.

METHODS

STUDY DESIGN AND POPULATION

Cross-sectional study, with information from PeNSE, a survey carried out with 51,192 students from the 9^th grade from 26 federal capitals and the Federal District, in 2015.

In the sample of PeNSE 2015, the 2013 School Census register was used, and schools that reported having 9^th grade classes in elementary school (formerly 8^th grade) had their morning classes period included. The sample was dimensioned in order to estimate population parameters (proportions or prevalence) in several geographical domains, covering the 27 capitals and the five major geographic regions of the country.

DATA COLLECTION

Data collection was carried out in classrooms anonymously and individually, through a self-administered questionnaire, using a handheld computer, the personal digital assistant. The questionnaire was organized into thematic modules that included sociodemographic and family context characteristics, as well as exposure to various health risk and protection factors. More methodological details are described in the specific reports for each survey²⁴24. Instituto Brasileiro de Geografia e Estatística. Pesquisa Nacional de Saúde Escolar. Rio de Janeiro: IBGE; 2012..

Only data regarding 9^th grade students from the federal capitals and the Federal District were included. The choice of the 9^th grade was justified by the minimum schooling considered necessary to answer the self-administered questionnaire, in addition to the proximity of the reference age (13 to 15 years) recommended by the World Health Organization.

STUDY VARIABLES

Food consumption was measured using the frequency of consumption, in the seven days preceding the survey, of seven foods: beans, vegetables, fresh fruit; soft drinks, sweets, fried snacks and lunch meats. The first three were considered healthy eating markers, and the last four were considered unhealthy eating markers. This classification was based on nutritional recommendations for the prevention of chronic non-communicable diseases, and also on evidence that suggests the association of these variables with overweight and other risk factors for chronic non-communicable diseases, such as dyslipidemias²⁵25. Barbosa Filho VC, Campos W, Lopes AS. Epidemiology of physical inactivity, sedentary behaviors, and unhealthy eating habits among Brazilian adolescents: a systematic review. Ciên Saúde Colet 2014; 19(1): 173-93. http://dx.doi.org/10.1590/1413-81232014191.0446
https://doi.org/http://dx.doi.org/10.159... ^,2626. Pearson N, Braithwaite RE, Biddle SJ, Van Sluijs EM, Atkin AJ. Associations between sedentary behaviour and physical activity in children and adolescents: a meta-analysis. Obes Rev 2014; 15(8): 666-75. https://doi.org/10.1111/obr.12188
https://doi.org/https://doi.org/10.1111/... ^,2727. Fletcher EA, McNaughton SA, Lacy KE, Dunstan DW, Carson V, Salmon J. Mediating effects of dietary intake on associations of TV viewing, body mass index and metabolic syndrome in adolescents. Obes Sci Pract 2016; 2(3): 232-40. https://dx.doi.org/10.1002%2Fosp4.60
https://doi.org/https://dx.doi.org/10.10... .

The consumption of these foods was expressed in two ways:

SB was evaluated in hours per day, collected through the following question: On an ordinary weekday, how long do you sit watching television, using a computer, playing video games, talking with friends or doing other activities? (Do not count Saturday, Sunday, holidays and time spent sitting at school). The response options were: up to 1 hour a day; more than 1 hour and up to 2 hours a day; more than 2 and up to 3; more than 3 and up to 4; more than 4 and up to 5; more than 5 and up to 6; more than 6 and up to 7; more than 7 and up to 8; more than 8 hours a day.

The time spent on SB was dichotomized in ≤ 2 hours or > 2 hours. This cutoff point was based on the American Academy of Pediatrics²⁹29. American Academy of Pediatrics. Children, adolescents, and television. Pediatrics 2001; 107(2): 423-6. https://doi.org/10.1542/peds.107.2.423
https://doi.org/https://doi.org/10.1542/... , which recommends two hours as a maximum screen time limit for children over two years old and for teenagers.

The following variables were included in the analyzes as possible confounders: gender (male, female), age (≤ 13, 14, 15 and 16 years old or over), self-reported skin color (white, black, yellow/indigenous, mixed race), maternal schooling (didn’t study; incomplete elementary school; incomplete high school; incomplete higher education; complete higher education), asset index (in fifths) and geographic region. The asset index was constructed based on possession of a landline telephone, a computer (desktop or notebook, laptop, etc.), car and/or motorcycle, as well as the number of bathrooms with shower and internet access at home. The possession of a cell phone by the adolescents and the hiring of a maid at home (for three or more days a week) were also questioned. The construction of the asset index was done using the first component obtained based on an analysis of main components³⁰30. Barros AJ, Victora CG. Indicador econômico para o Brasil baseado no Censo Demográfico de 2000. Rev Saúde Pública 2005; 39(4): 523-9. http://dx.doi.org/10.1590/S0034-89102005000400002
https://doi.org/http://dx.doi.org/10.159... .

Regarding PA, it was decided to re-analyze only specific questions about leisure PA and active commuting to school. Physically active adolescents were defined as those who added 300 min/week or more of PA practice, including all domains (physical education classes at school, PA outside and inside the school). Also, the following percentages were estimated:

DATA ANALYSIS

Descriptive analyzes were performed and the absolute and relative frequencies of dependent and independent variables were calculated. Statistical analyzes were carried out using the Stata 12.0 statistical package (Statacorp LP, College Station, United States).

Bivariate analyzes were carried out on the associations and χ² test was performed for heterogeneity and for linear trend in the case of ordinal variables. Logistic regressions with variance were used to estimate odd and adjusted and unadjusted ratios. For comparison between the sexes, the χ² test was used. The results were expressed by adjusted odds ratios (OR) with respective 95% confidence intervals (95%CI), considering a statistically significant association of p<0.05.

ETHICAL ASPECTS

This study was based on public data (http://www.ibge.gov.br), and the original project of the survey was approved by the National Research Ethics Commission (CONEP), of the National Health Council, which regulates and approves health research involving human beings, through CONEP opinion No. 1.006.467, of March 30, 2015.

The Informed Consent Term was included in the smartphone, and the participants indicated that they were aware of participation in the research. Total anonymity and privacy were guaranteed to the participants; the Brazilian Institute of Geography and Statistics does not provide variables that can identify the participants in their database.

RESULTS

Of the 51,192 adolescents studied, 48.6% were female, and 51.4% were male (Table 1). Of the total, 41.7% were mixed race, 52.4% were 14 years old, 44.6% were from the Southeast Region, 25.8% of mothers had completed elementary school, and 26.2% were in the 4^th income quintile (Table 1).

Table 2 shows the comparison between girls and boys in eating habits and PA, with a significant difference (p ≤ 0.001) between the consumption of beans and fruits, which was more frequent in boys. Regarding the consumption of fried snacks, sweets and lunch meats, it was higher in girls (p ≤ 0.001). It was observed that girls practiced more PA in physical education classes, while boys practiced PA outside of school more than three days/week, thus showing a significant difference when compared to girls (p ≤ 0.001).

Regarding SB, 73.7% of students reported staying for up to two hours in front of the TV (Table 2). When asked about PA recommendations (60 min/day), it was observed that boys were more active compared to girls (p ≤ 0.001) (Table 2).

The associations between regular consumption of healthy eating markers and the recommendation of PA and maternal schooling and income are shown in Table 3.

Regarding the association between the level of maternal schooling (complete high school) and the consumption of beans, it was found that boys whose mothers had completed high school had 20% (OR = 0.8; 95%CI 0.73 - 0.87) were less likely to consume beans compared to boys whose mothers did not formally study.

As for the association between the level of maternal schooling (complete high school) and the consumption of vegetables, it was found that boys whose mothers had completed elementary school had 30% (OR = 1.3; 95%CI 1.2 - 1.4) more likely to consume vegetables compared to boys whose mothers did not formally study.

We found no associations between income and healthy eating.

Table 4 shows the associations between regular consumption of unhealthy food and SB markers and maternal schooling and income. We noticed associations between the consumption of soft drinks, lunch meats and fried snacks with maternal schooling.

DISCUSSION

The results presented revealed that, among adolescents in the Brazilian capitals, there was frequent consumption of unhealthy food markers, that is, lower than recommended³¹31. Martins APB, Levy RB, Claro RM, Moubarac JC, Monteiro CA. Participação crescente de produtos ultraprocessados na dieta brasileira (1987-2009). Rev Saúde Pública 2013; 47(4): 656-65. http://dx.doi.org/10.1590/S0034-8910.2013047004968
https://doi.org/http://dx.doi.org/10.159... ^,3232. Couto SF, Madruga SW, Neutzling MB, Silva MC. Frequência de adesão aos “10 Passos para uma alimentação saudável” em escolares adolescentes. Ciên Saúde Coletiva 2014; 19(5): 1589-99. http://dx.doi.org/10.1590/1413-81232014195.21392013
https://doi.org/http://dx.doi.org/10.159... , in addition to the increase in SB and the reduction in the practice of PA.

The 2008-2009 Household Budget Survey (POF) found that adolescents had inadequate food consumption and that they had a worse diet than adults and the elderly³³33. Instituto Brasileiro de Geografia e Estatística (IBGE). Pesquisa de Orçamentos Familiares 2008-2009: Análise do consumo alimentar pessoal no Brasil. Rio de Janeiro: IBGE ; 2011.. The POF also found that adolescents consumed four times more sandwich cookies (12.3 g/day) and twice as much soda as adults³³33. Instituto Brasileiro de Geografia e Estatística (IBGE). Pesquisa de Orçamentos Familiares 2008-2009: Análise do consumo alimentar pessoal no Brasil. Rio de Janeiro: IBGE ; 2011..

These data refer to the importance of building healthy eating habits, due to their relevance both as a protective factor to the development of diseases and to the improvement of health conditions in adulthood when the appropriate measures are adopted from an earlier ages³⁴34. Pedraza DF, Silva FA, Melo NLS, Araújo EMN, Sousa CPC. Estado nutricional e hábitos alimentares de escolares de Campina Grande, Paraíba, Brasil. Ciên Saúde Coletiva 2017; 22(2): 469-77. http://dx.doi.org/10.1590/1413-81232017222.26252015
https://doi.org/http://dx.doi.org/10.159... ^,3535. Conde WL, Monteiro CA. Nutrition transition and double burden of undernutrition and excess of weight in Brazil. Am J Clin Nutr 2014; 100(Supl. 6): 1617S-22S. https://doi.org/10.3945/ajcn.114.084764
https://doi.org/https://doi.org/10.3945/... .

The Brazilian industrialized standard was composed of high consumption of foods such as fried snacks, soft drinks, sweets and lunch meats. This pattern of food consumption is similar to that identified in children from Salvador (BA), consisting of fried foods, sweets, snacks and soft drinks/artificial juice³⁶36. D’Innocenzo S, Marchioni DML, Prado MS, Matos SMA, Pereira SRS, Barros AP, et al. Condições socioeconômicas e padrões alimentares de crianças de 4 a 11 anos: estudo SCAALA - Salvador /Bahia. Rev Bras Saude Mater Infant 2011; 11(1): 41-9. http://dx.doi.org/10.1590/S1519-38292011000100005
https://doi.org/http://dx.doi.org/10.159... .

Data from the second edition of PeNSE 2012 showed prevalence rates of regular consumption (≥ 5 days/week) of sweets, soft drinks, cookies, fried snacks and packaged snacks in, respectively, 41.3, 33.3, 32.5, 15.8 and 13% of adolescents³⁷37. Azeredo CM, Rezende LFM, Canella DS, Claro RM, Castro IRR, Odo CL, et al. Dietary intake of Brazilian adolescents. Public Health Nutr 2015; 18(7): 1215-24. https://doi.org/10.1017/S1368980014001463
https://doi.org/https://doi.org/10.1017/... . The present study showed a high prevalence of Brazilian schoolchildren with inadequate eating habits (Table 2), such as: soft drinks (girls = 35.7% and boys = 40.7%), sweets (girls = 57.7% and boys = 46.7%), lunch meats (girls = 46.8% and boys = 43.7%) and fried snacks (girls = 21.5% and boys = 20.2%).

It was observed that more than 80% of girls and 63% of boys did not reach the recommendation of 300 min/week of PA (Table 2), although 50% of schools offer Physical Education classes three days a week. Currently, there is a great concern from physical education teachers with regard to their praxis, considering that a large number of students do not participate effectively in physical education classes. There are several reasons that influence this lack of interest, including the lack of adequate materials and facilities for the class, the lack of trained professionals, as well as social and family problems, which can also trigger discouragement for participating in classes, which normally follow a routine action of walking to the court and simply settling down.

Thus, it is up to Physical Education teachers to use the knowledge acquired in their academic training to strengthen the understanding of physical education as a curricular discipline that introduces and integrates students into body culture.

Reduced participation in physical education classes is not an isolated phenomenon in our country. According to the results of the Youth Risk Behavior Surveillance System, which has been monitoring adolescent PA practice since 1991³²32. Couto SF, Madruga SW, Neutzling MB, Silva MC. Frequência de adesão aos “10 Passos para uma alimentação saudável” em escolares adolescentes. Ciên Saúde Coletiva 2014; 19(5): 1589-99. http://dx.doi.org/10.1590/1413-81232014195.21392013
https://doi.org/http://dx.doi.org/10.159... ^,3333. Instituto Brasileiro de Geografia e Estatística (IBGE). Pesquisa de Orçamentos Familiares 2008-2009: Análise do consumo alimentar pessoal no Brasil. Rio de Janeiro: IBGE ; 2011., only 55% of high school students were enrolled in physical education classes in 2003, and of these, only 28% regularly attended these classes.

A recent systematic review of Latin American literature in the field of PA interventions concluded that the promotion of PA in the school environment is highly recommended and effective³⁴34. Pedraza DF, Silva FA, Melo NLS, Araújo EMN, Sousa CPC. Estado nutricional e hábitos alimentares de escolares de Campina Grande, Paraíba, Brasil. Ciên Saúde Coletiva 2017; 22(2): 469-77. http://dx.doi.org/10.1590/1413-81232017222.26252015
https://doi.org/http://dx.doi.org/10.159... .

There is strong evidence showing that physical education classes can be an effective strategy to increase PA among students³⁵35. Conde WL, Monteiro CA. Nutrition transition and double burden of undernutrition and excess of weight in Brazil. Am J Clin Nutr 2014; 100(Supl. 6): 1617S-22S. https://doi.org/10.3945/ajcn.114.084764
https://doi.org/https://doi.org/10.3945/... , especially in Brazil, where school physical education is mandatory.³⁶36. D’Innocenzo S, Marchioni DML, Prado MS, Matos SMA, Pereira SRS, Barros AP, et al. Condições socioeconômicas e padrões alimentares de crianças de 4 a 11 anos: estudo SCAALA - Salvador /Bahia. Rev Bras Saude Mater Infant 2011; 11(1): 41-9. http://dx.doi.org/10.1590/S1519-38292011000100005
https://doi.org/http://dx.doi.org/10.159... . In the same direction, school meals are offered free of charge in most public schools in the country, which could be better used to promote healthy eating habits³⁷37. Azeredo CM, Rezende LFM, Canella DS, Claro RM, Castro IRR, Odo CL, et al. Dietary intake of Brazilian adolescents. Public Health Nutr 2015; 18(7): 1215-24. https://doi.org/10.1017/S1368980014001463
https://doi.org/https://doi.org/10.1017/... . However, some barriers (unmotivated and/or unprepared professionals, lack of financial, physical and material resources and outdated curriculum structure) would need to be overcome for schools to offer quality physical education and food, in line with the goals of health promotion³⁸38. Ribeiro EHC. Efeito de dois programas de intervenção no nível de atividade física de adolescentes matriculados em escolas da rede pública de ensino da Zona Leste da cidade de São Paulo, SP [dissertação]. São Paulo: Faculdade de Saúde Pública, Universidade de São Paulo; 2009.^,3939. Hoehner CM, Soares J, Perez DP, Ribeiro IC, Joshu CE, Pratt M, et al. Physical activity interventions in Latin America: a systematic review. Am J Prev Med 2008; 34(3): 224-33. https://doi.org/10.1016/j.amepre.2007.11.016
https://doi.org/https://doi.org/10.1016/... . In this context, school can emerge as a privileged environment for the development and learning of health skills as a structuring concept, also involving different levels of management, teacher training and curricular adaptations, helping to define a sustainable policy for health in the school community⁴⁰40. Fernandes PS, Bernardo CO, Campos RMMB, Vasconcelos FAG. Evaluating the effect of nutritional education on the prevalence of overweight/ obesity and on foods eaten at primary schools. J Pediatr (Rio J) 2009; 85(4): 315-21. https://doi.org/10.2223/JPED.1917
https://doi.org/https://doi.org/10.2223/... ^,4141. Kain J, Vio F, Albala C. Obesity trends and determinant factors in Latin America. Cad Saúde Pública 2003; 19(Supl. 1): 77-86. http://dx.doi.org/10.1590/S0102-311X2003000700009
https://doi.org/http://dx.doi.org/10.159... .

Hallal et al.⁴²42. Hallal PC, Bertoldi AD, Gonçalves H, Victora CG. Prevalência de sedentarismo e fatores associados em adolescentes de 10-12 anos de idade. Cad Saúde Pública 2006; 22(6): 177-87. http://dx.doi.org/10.1590/S0102-311X2006000600017
https://doi.org/http://dx.doi.org/10.159... demonstrated a positive relationship between the number of hours per day watching television and physical inactivity in schoolchildren. There is a current trend to use screen time as an indicator of sedentary life, as it is an easily obtainable variable and because it is a habit that may decrease the practice of PA.

A study conducted with adolescents from Santa Catarina, Brazil, found that more than 70% watched television or used a computer/videogame for more than two hours a day⁴³43. Silva KS, Nahas MV, Hoefelmann LP, Lopes AS, Oliveira ES. Associações entre atividade física, índice de massa corporal e comportamentos sedentários em adolescentes. Rev Bras Epidemiol 2008; 11(1): 159-68. http://dx.doi.org/10.1590/S1415-790X2008000100015
https://doi.org/http://dx.doi.org/10.159... , a result similar to that observed in the present study. Gordon-Larsen et al.⁴⁴44. Gordon-Larsen P, Nelson MC, Popkin BM. Longitudinal physical activity and sedentary behavior trends: adolescence to adulthood. Am J Prev Med 2004; 27(4): 277-83. https://doi.org/10.1016/j.amepre.2004.07.006
https://doi.org/https://doi.org/10.1016/... , when assessing longitudinal trends in sedentary behavior, showed that, among the adolescents participating in the study, a quarter showed sedentary behavior ≤ 2 hours a day and maintained this habit in adulthood.

In addition to the high prevalence of SN among PeNSE students, the results show that this habit is associated with a higher consumption of sweets and lunch meats, regardless of sociodemographic characteristics. Our findings are worrisome and consistent with those of other national studies⁴⁵44. Dias PJP, Domingos IP, Ferreira MG, Muraro AP, Sichieri R, Gonçalves-Silva RMV. Prevalence and factors associated with sedentary behavior in adolescents. Rev Saúde Pública 2014; 48(2): 266-74. https://doi.org/10.1590/s0034-8910.2014048004635
https://doi.org/https://doi.org/10.1590/... ^,4645. Friedrich RR, Polet JP, Schuch I, Wagner MB. Effect of intervention programs in schools to reduce screen time: a meta-analysis. J Pediatr 2014; 90(3): 232-41. https://doi.org/10.1016/j.jped.2014.01.003
https://doi.org/https://doi.org/10.1016/... .

The high prevalence of elevated time in front of TV is of particular concern because of the obesogenic role of TV. Studies on the topic show that this effect can be more attributed to the increased intake of high energy density foods while watching TV than due to the decrease in PA levels⁴⁷46. Lucena JMS, Cheng LA, Cavalcante TLM, Silva VA, Farias Júnior JCF. Prevalência de tempo excessivo de tela e fatores associados em adolescentes. Rev Paul Pediatr 2015; 33(4): 407-14. http://dx.doi.org/10.1016/j.rpped.2015.04.001
https://doi.org/http://dx.doi.org/10.101... ^,4847. Silva KS, Silva Lopes A, Dumith SC, Garcia LM, Bezerra J, Nahas MV. Changes in television viewing and computers/videogames use among high school students in Southern Brazil between 2001 and 2011. Int J Public Health 2014; 59(1): 77-86. https://doi.org/10.1007/s00038-013-0464-3
https://doi.org/https://doi.org/10.1007/... .

Our study observed that the lower the level of maternal schooling, the greater the likelihood that the adolescent will have a poor quality diet. These data are in line with the study by Molina et al.⁴⁹48. Biddle SJH, Petrolini I, Pearson N. Interventions designed to reduce sedentary behaviours in young people: a review of reviews. Br J Sports Med 2014; 48(3): 182-6. https://doi.org/10.1136/bjsports-2013-093078
https://doi.org/https://doi.org/10.1136/... , who observed that low maternal schooling increased the likelihood of children consuming lower quality food, as maternal schooling probably determines the ability to buy healthier foods, as well as access to adequate information.

This study has some limitations, which refer to the impossibility of making causal inferences between the outcome under study and the inclusion of only adolescents who were attending school and present in the classroom when the questionnaire was applied, a decision that may have caused some bias in the results, since absenteeism or school dropout rates may be related to the factor studied. However, this limitation does not make the results unfeasible, as the study was carried out with an expressive sample. The information collected on the adolescents, which was self-reported, allows underestimates or overestimates of the indicators studied, depending on the lesser or greater social acceptance of the behaviors asked. As this is a cross-sectional survey, caution is required when interpreting the results, as it is not possible to establish a temporality or causality relationship for part of the associations found.

PeNSE 2015 is a school-based and nationwide survey, which is a strong point in the studies carried out using its database. It can also be highlighted that, when comparing other data from the first two editions of PeNSE (2009 and 2012), this study adds information, as it verifies associations between unhealthy behaviors and sociodemographic characteristics, data that were not evaluated in national surveys with schoolchildren.

The consumption of unhealthy foods and physical inactivity plus SB have increased in the Brazilian population, and the prevalence among adolescents was shown to be high in the present study. In this sense, more studies should be carried out focusing on reducing these prevalence rates. There is a need for wide dissemination of the importance of good nutrition and the practice of regular PA, with a focus on public policies at school.

Thus, it is important to reduce prolonged sitting time, in addition to increasing PA practice. Thus, parents need to be aware of this control, since the longest time spent on SB occurs in the family environment.

These results point to the need to intensify and expand health promotion actions aimed at young people. The current Brazilian context is conducive to this. In addition, the maintenance of the surveillance system for health risk factors directed at adolescents should be part of the list of future actions.

CONCLUSION

These findings suggest that inactive adolescents exhibit other unhealthy behaviors that may increase the risk of chronic non-communicable diseases in adulthood. Thus, interventions in the school environment should focus not only on increasing PA levels, but also prioritize approaches to healthy lifestyles.

Thus, through the knowledge of food consumption by adolescents, it is possible to plan actions that are capable of promoting positive changes in eating behavior and, thus, avoiding health problems resulting from inadequate nutrition.

References

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