Since the 80s, a reduction in the malnutrition prevalence among Brazilian children and adolescents has been observed 1 . However, it has been observed that the overweight and obesity prevalence in Brazilian children and adolescents (6–18 years) has tripled, jumping from 4% in the 1970s to 13% in 1997 2 . Information from the Family Budget Survey, conducted by the Brazilian Institute of Geography and Statistics, in 2008–2009, revealed that one in three children aged five to nine years of age was overweight, and among adolescents (ten to 19 years), overweight was found to be 25.4% 3 .

High overweight and obesity prevalence has been observed in developed and developing countries, and obesity is considered an important public health problem worldwide 4 5 , mainly due to the close relationship between inadequate nutritional status and development of cardiovascular diseases and early mortality 6 7 . Overweight is multifactorial in origin, with important genetic 8 and environmental factors such as inadequate eating habits, for example the preference for quick meals, consisting mostly of high-calorie foods like snacks and soft drinks 9 .

In this sense, the overweight and obesity diagnosis in childhood and adolescence is of great relevance to public health 10 , considering that the presence of obesity in childhood and adolescence tends to persist into adulthood 11 .

Despite the numerous indicators to define overweight and obesity, body mass index (BMI) has been the most common method to assess the weight status and health risks of children and adolescents 12 , being widely used in epidemiological studies 13 14 , due to its easy application, low operation cost and possibility of comparison with other studies. The World Health Organization 15 widely recommends the use of this anthropometric indicator for assessing the health status of people of any age.

There are several criteria for BMI classification in children and adolescents in literature 16 17 18 19 . Among them, the criteria that used samples from different countries, including Brazil, to establish cutoff points stand out, for example, Cole et al. 17 and Onis et al. 19 . Besides these criteria widely disseminated in literature, there is also the criteria of Conde & Monteiro 18 , which establishes cutoff points for overweight and obesity with data exclusive of Brazilian children and adolescents. It is noteworthy that the cutoff points internationally accepted are those of CDC 16 , IOTF 17 and WHO 19 , while the criteria of Conde and Monteiro 18 are only valid in Brazil.

Given that overweight and obesity are increasing among young Brazilians, it is important to investigate whether the criteria used for this classification are similar in terms of overweight and obesity prevalence, as well as if the factors associated with this prevalence are the same for the different criteria used. Thus, the aim of this study was to describe and compare the nutritional status of adolescents using three criteria for nutritional status classification, and to investigate whether factors associated with overweight and obesity differ among the three different criteria.

For this cross-sectional epidemiological study, data were collected from the “Esporte Brasil” Project (PROESP-BR) of the National Secretariat for High-Performance Sports - Ministry of Sports. This project is a permanent observatory of growth, development and nutritional status indicators of Brazilian children and adolescents of both sexes, which main objective is to define the somatomotor profile, lifestyle and motor fitness factors of children and adolescents in Brazil. More detailed information about the design and methodological aspects of the PROESP-BR project has been previously published 20 .

The sample consisted of 33.728 adolescents aged 11 to 17 years, with 19,002 males. The age group of 11–12 years comprised 15,103 individuals (53.8% of males); the age group of 13–14 years comprised 13,119 students (58.4% of males) and that of 15–17 years comprised 5,506 subjects (58.4% of males).

For boys in all age groups, the Conde & Monteiro and WHO criteria estimated higher overweight prevalence when compared to IOTF criteria. At the age group of 11–12 years, the overweight prevalence estimated by the WHO criteria was higher when that estimated by the Conde & Monteiro criteria. In the age groups of 13–14 and 15–17 years, the prevalence estimated by the Conde & Monteiro criteria was higher than that estimated by the WHO criteria (Table 1).

* Significant difference in relation to the proportion observed by the Conde & Monteiro classification criteria (p <0.05).

† Significant difference in relation to the proportion observed by the IOTF classification criteria (p <0.05).

‡ Significant difference compared to the proportion observed by the WHO classification criteria (p <0.05).

For girls (Table 1), it was observed that in all age groups, the Conde & Monteiro and WHO criteria estimated higher overweight prevalence when compared to IOTF criteria. In the age group of 11–12, 13–14 years and considering the entire sample, the prevalence estimated by the Conde & Monteiro criteria was higher than that estimated by the WHO criteria.

Table 2 shows the concordance between the three criteria for overweight diagnosis. In males, it was observed that at the age of 11–12 years, the concordance between the Conde & Monteiro and IOTF criteria was higher than that obtained between IOTF and WHO and WHO and Conde & Monteiro criteria. At the age of 13–14 years and considering all age groups, the concordance obtained between Conde & Monteiro and IOTF and WHO and Conde & Monteiro criteria was higher than that obtained between IOTF and WHO.

* Concordance greater than the comparison between Conde & Monteiro vs IOTF (for same sex and age group).

† Concordance greater than the comparison between IOTF vs WHO (for same sex and age group).

‡ Concordance greater than the comparison between WHO vs. Conde & Monteiro (for same sex and age group).

In females, it was observed that at the age of 11–12, 13–14 years and considering all age groups, the correlation between WHO and Conde & Monteiro criteria was greater than the other criteria (Table 2).

Table 3 shows the association between overweight and obesity and demographic variables according to the Conde & Monteiro classification criteria. The likelihood of adolescents of being overweight was higher among male adolescents, 11–12 and 13–14 years and living in the Midwestern and Southern regions of Brazil.

* Odds ratio adjusted for all variables.

Note: Bold - variables with p-value <0.05 in the Wald test. OR odds ratio, CI confidence interval.

Regarding obesity, association was found between age group and geographic region. The likelihood of adolescents of being obese when compared to normal weight was higher in those aged 11–12 and 13–14 years and living in the Midwestern, Southeastern and Southern regions of Brazil (Table 3). Furthermore, it was found that boys were less likely to be obese compared to girls.

Table 4 shows the association between overweight and obesity and demographic variables according to the IOFT classification criteria. The results show association between age group and geographic region and overweight. The likelihood of adolescents of being overweight was higher among adolescents aged 11–12 and 13–14 years and living in the Midwestern, Southeastern and Southern regions of Brazil.

* Odds ratio adjusted for all variables.

Note: Bold - variables with p-value <0.05 in the Wald test. OR odds ratio, CI confidence interval.

Regarding obesity, association was found between age group and geographic region. The likelihood of adolescents of being obese when compared to normal weight was higher in those aged 11–12 and 13–14 years and living in the Midwestern, Southeastern and Southern regions of Brazil (Table 4).

Table 5 shows the association between overweight and obesity and demographic variables according to the WHO classification criteria. The results show association between age group and geographic region with overweight. The likelihood of adolescents of being overweight was higher among adolescents aged 11–12 and 13–14 years and living in the Midwestern, Southeastern and Southern regions of Brazil.

* Odds ratio adjusted for all variables.

Note: Bold - variables with p-value <0.05 in the Wald test. OR odds ratio, CI confidence interval.

Regarding obesity, association was found between sex, age group and geographic region. The likelihood of adolescents of being obese when compared to normal weight was higher in males, 11–12 and 13–14 years and living in the Midwestern, Southeastern and Southern regions of Brazil (Table 5).

This is the first study carried out with adolescents from all geographic regions of Brazil, which has characteristics of a country with continental dimensions, which different ethnicities, customs and traditions. Furthermore, this study evaluated if the factors associated (sex, age and geographic region) with overweight and obesity are the same for the different classification criteria used. It is noteworthy that the three criteria used have in common the fact of using arbitrary cutoff points and adjusting BMI values that characterize underweight, overweight and obesity in adults for the population of children and adolescents 23 .

The three references used in this study showed marked differences between each other. Both for boys and girls, increased overweight prevalence was observed by the Brazilian reference of Conde & Monteiro 18 , followed by WHO 19 and IOTF 17 .

Some studies carried out in Brazil 24 25 and elsewhere 26 27 also compared different criteria for nutritional status classification in children and adolescents. Most of these studies demonstrated that the criteria for nutritional status classification differ, but a study conducted in adolescents of Florianópolis, Santa Catarina, Brazil, Farias Jr et al. 24 found no significant differences in the overweight prevalence determined by the different BMI classification criteria, except for male adolescents, in which the BMI values recommended by Conde & Monteiro 18 showed higher prevalences compared to the other criteria.

Contrasting these findings, a study carried out in Rio Grande, Rio Grande do Sul, Brazil 28 with students aged 10 to 15 years revealed that the overweight prevalence was significantly higher using the Conde & Monteiro 18 criteria than using IOTF 17 . In Canadian preschoolers 27 , the overweight prevalence using the WHO criteria was higher than that using the IOTF and the Centers for Disease Control and Prevention (CDC) criteria 29 .

One possible explanation for the higher overweight prevalence found using the criteria proposed by Conde & Monteiro 18 is due to the fact that the critical BMI values are lower than those of the other criteria, as already observed by Farias Jr et al. 24 . Moreover, it could be speculated that unlike criteria of IOTF 17 and WHO 19 , the cutoff points of Conde and Monteiro 18 were defined with the specific population of Brazil. Thus, one might think that the prevalence detected by the criteria proposed by Conde and Monteiro 18 may represent the real problem of the high overweight and obesity prevalence in Brazilian adolescents.

When the Kappa test was applied, high concordance between criteria of Conde & Monteiro 18 and WHO 19 was found for all age groups and for the data set. Moreover, strong concordance (kappa> 0.75) was observed for the most overweight classifications analyzed. These results corroborate the findings of Dumith and Farias Jr 28 , who also found that the concordance between criteria of Conde & Monteiro and WHO was higher than the concordance obtained between the other criteria.

Regarding associated factors, similar associations were found for the three criteria for BMI classification examined: being male, age 11–12 and 13–14 years, living in the Midwestern, Southeastern and Southern regions of Brazil had greater chances of showing overweight. A study conducted among adolescents in southern Brazil revealed that the direction and magnitude of the association measures were similar between criteria for BMI classification 28 . Corroborating these findings, Abrantes et al. 30 also observed higher overweight prevalence among adolescents in southeastern Brazil when compared to those of northeastern Brazil.

The results of this study make some hypotheses to be raised: the lower overweight prevalence in girls may be related to a greater concern with body image 31 . The decline in overweight and obesity with increasing age is expected, since moderate excess weight might be compensated by growth, and may even represent a positive aspect of the obesity treatment 32 ; however, excess weight in adolescence should not be underestimated, since there is an increased risk of persisting into adulthood 33 . It is assumed that differences between regions are related to different socioeconomic development between regions 21 , resulting in a greater prevalence in the most developed regions. The higher overweight prevalences found in the Midwestern, Southeastern and Southern regions can be explained due to the difference socioeconomic development between regions, resulting in a greater prevalence in more developed regions, where there are better conditions of purchase and choice of food 1 . Nevertheless, there is an increasing trend in the prevalence of overweight in the North and Northeast and the lower socioeconomic levels 1 .

The present study has the following limitations: 1) the sample selection was performed only in schools that joined the PROESP project, and thereby the participation of more adolescents with obesity characteristic was limited, 2) data are restricted to adolescent students who were in school during the period of data collection and could not be extrapolated to adolescents who were not enrolled in schools.

The findings of this study indicate that the criteria for BMI classification estimate overweight prevalence in a different way, and the criteria proposed by C & M resulted in higher prevalence in both sexes. Higher concordance between the Conde & Monteiro and WHO criteria was found for all age groups. The groups most vulnerable to showing overweight and obesity for the three criteria for BMI classification were males, age 11–12 and 13–14 years, and living in the Midwestern, Southeastern and Southern regions of Brazil.

The authors declare that they have no competing interests.

AP contributed to statistical analysis, data interpretation, and manuscript writing. DASS contributed to statistical analysis, data interpretation, and manuscript writing. ACAG contributed to the study design and the data acquisition. ELP contributed to revise it critically for important intellectual content. All authors read and approved the final manuscript.