The nutritional status of children and adolescents is a determining factor in their weight-height growth and intellectual development. Childhood obesity is now a major global public health concern. Once limited to developed countries, its prevalence has been rising in low-income nations since the 1990s. In 2016, the World Health Organization (WHO) estimated that there were 340 million children and adolescents (aged 5-19 years) who were obese or overweight in the world. The WHO recognizes obesity as a global epidemic and the most significant nutritional disorder.^1,2

The ERICA study (Cardiovascular Risk in Adolescents), conducted in 2016 with Brazilian children and adolescents, reported a prevalence of overweight and obesity at 17.1% and 8.4%, respectively. It also identified associated comorbidities, including hypercholesterolemia (20.1%), metabolic syndrome (2.6%), and systemic arterial hypertension (9.6%), conditions linked to an increased risk of cardiovascular disease.^3-5

This scenario underscores the importance of adopting healthy lifestyle habits during childhood and adolescence. Reducing the intake of calorie-dense foods such as fried items, ultra-processed products, and animal-based foods while increasing the consumption of plant-based options and engaging in physical activity is crucial for preventing cardiovascular and other chronic non-communicable diseases in adulthood.

In this sense, this study aims to assess the prevalence of overweight, obesity, and high blood pressure (BP) among children in Bahia's backlands and to determine whether these conditions differ between rural and urban areas.

The sample consisted of 461 schoolchildren, 264 (57.3%) from urban areas and 238 (51.6%) of whom were male. The mean age was 8 years (± 2), as can be seen in the Central Illustration. The mean and SD of BMI, mean SBP and mean DBP of the 461 schoolchildren are shown in Table 1.

The mean age of the schoolchildren from rural areas (7.8 ± 1.58) was not different from the average for students in urban areas (7.7 ± 1.5) (p = 0.47).

Figure 2 and Table 1 show the data on nutritional classification based on the Z-score (BMI – Age), with 311 (67.5%) students classified as normal weight, 75 (16.3%) as overweight, 40 (8.7%) as obese, 18 (3.9%) as underweight, 14 (3.0%) as severely obese and 3 (0.7%) students classified with extreme underweight. This distribution is also shown in the Central Illustration.

Among the individuals belonging to the underweight/normal weight group, 174 (52.4%) were male, while among those overweight or obese, 65 (50.4%) were female. Of the 461 students, 34 (7.4%) had increased WC, 24 (70.6%) of whom were male. Regarding the prevalence of systemic arterial hypertension, 17 (3.7%) students had high BP, 20 (4.3%) were hypertensive, and among the group of individuals with high BP/Hypertension, 19 (51.4%) were male, as can be seen in the Central Illustration.

Data from the nutritional classification based on the Z-Score (BMI–Age) comparative between the rural and urban areas are shown in Table 2. The results reveal that, among the individuals from the rural area, those belonging to the extreme underweight, underweight and normal weight groups prevail (75.1%). In the urban area, in turn, 69.7% are classified as extremely thin, thin and eutrophic and 30.3% are classified as overweight and obese. No significant difference was observed in the proportion of individuals in each nutritional category between the areas (p = 0.21). Regarding the increased waist circumference, there was a higher prevalence of schoolchildren with increased waist circumference in urban areas compared to rural areas: 25 (9.5%) vs. 9 (4.6%) (p = 0.049) (Table 2 and Central Illustration).

Table 3 represents data on systemic BP according to the area. Among individuals from rural areas, 178 (90.4%) were normotensive, while in urban areas, 246 (93.2%) of the schoolchildren were normotensive. No significant difference was observed in the proportion of individuals with increased BP or hypertension in rural and urban areas.

Schoolchildren from rural areas had a higher mean SBP (92.6 ± 10.8) than those from urban areas (88.8 ± 8.7), (p = 0.001), with no difference for DBP (60.5 ± 6.9 vs. 60.36 ± 8.39), (p = 0.79), which is shown in the Center Figure.

The prevalence of overweight or obesity was not higher in individuals with high BP or hypertension, as shown in Table 4. In the group with high BP or hypertension, 27 (73%) were extremely underweight, underweight, or eutrophic, while 10 (27%) were overweight or obese. On the other hand, among normotensive individuals, 305 (71.9%) were classified as extremely thin, thin, or eutrophic, and 119 (28.1%) were overweight or obese. Likewise, the prevalence of increased waist circumference was not higher in individuals with high BP or hypertension and vice versa, as shown in Table 4.

Among individuals with high BP or hypertension, 33 (89.2%) had normal waist circumference, while 4 (10.8%) had increased waist circumference. Among normotensive individuals, 394 (92.9%) had normal waist circumference, and 30 (7.1%) had increased waist circumference, with no significant difference between the groups.

The literature shows a growing trend in the prevalence of overweight and obesity in school-age children, with childhood obesity being a key risk factor for adult obesity, premature death, and cardiovascular changes in adulthood. In this context, anthropometric measurements such as BMI and waist circumference, along with BP, are crucial tools for assessing the health of children and adolescents.

The prevalence of overweight in this study was 27.9% and that of increased waist circumference was 7.4%. Similar results were found by Ribas and Silva, 2012 (22.2%) in schoolchildren in the same age group (6-19 years) in the city of Belém do Pará (Brazil).⁹ In the study by Bloch et al. (2016), a prevalence of 25.5% of excess weight was found in adolescents.³ On the other hand, Oliveira et al.¹⁰ found a 67% prevalence of excess weight (overweight/obesity) and 65.3% of increased waist circumference in children and adolescents aged 4 to 18 years in the city of Feira de Santana (BA).

Together, these data emphasize the importance of early detection of excess weight and central obesity in children and suggest that waist circumference can be a valuable tool in assessing cardiovascular risk in both children and adolescents. Its measurement should be included in routine pediatric exams. The significance of early assessment of central obesity is further supported by the fact that, in adults, waist circumference is considered the most accurate anthropometric indicator of cardiovascular risk.¹¹

The diagnosis of systemic arterial hypertension in children and adolescents is still often delayed, mainly due to the lack of routine BP measurement in pediatric physical exams. In this study, a prevalence of 8% of individuals with high BP or hypertension was found. From a public health perspective, the estimated prevalence of systemic arterial hypertension in the pediatric population has rarely been summarized at a global level. A meta-analysis¹² of children and adolescents aged 19 years or younger revealed a 4% prevalence of hypertension (95% Confidence Interval, CI) and 9.67% (95% CI) of pre-hypertension, with no significant differences between sexes, rural and urban areas, or high- and low-income countries, as found in this study. However, the same meta-analysis showed a higher prevalence of systemic arterial hypertension in overweight (4.99%, 95% CI) and obese (15.27%, 95% CI) children and adolescents compared to those with normal BMI (1.9%, 95% CI), which was not observed in this study. A possible explanation for this discrepancy is that the prevalence of systemic arterial hypertension in children and adolescents increases with the onset and progression of puberty (associated with hormonal changes),¹² and this study focused on children up to 10 years old, most of whom were prepubertal. The higher prevalence of systemic arterial hypertension observed in overweight schoolchildren in the mentioned meta-analysis can be explained by the older age of the individuals rather than solely by their high BMI.

No significant difference was found in the proportion of lean/eutrophic and overweight individuals between rural and urban areas. However, most of the overweight individuals lived in urban areas. Likewise, since waist circumference reflects abdominal and visceral fat, a higher frequency of increased waist circumference was also observed in urban areas.

There is insufficient data in the literature to corroborate a higher prevalence of overweight and obesity in the child and adolescent population in urban or rural areas since multiple factors are involved in the genesis of a higher BMI, such as the socioeconomic development of the region in question, the population's level of education, the quality of nutrition, the physical activity profile practiced, in addition to genetic determinants.^13,14

Studies analyzing American children and adolescents found a higher prevalence of overweight and obesity in rural areas compared to urban areas. This was attributed to greater access to nutritional education, as well as more frequent prenatal care and pediatric medical follow-up in urban areas.^13,15 Conversely, studies conducted in low- and middle-income countries — such as Brazil — found a higher prevalence of overweight and obesity in urban areas compared to rural areas. The authors attributed this to the higher socioeconomic status in urban areas, which facilitates access to industrialized and processed foods, in contrast to the reliance on family farming products in rural areas. This finding can also be explained by the supposed lower prevalence of sedentary lifestyles in rural areas. As a low-income country, children in rural areas often travel long distances to attend school and participate in other activities, unlike their urban counterparts, who have better access to transportation options.¹⁶ Moreover, there is less access to education in developing countries, which justifies a lower level of awareness regarding the importance of a healthy diet and physical exercise. In contrast, in developed countries such as the United States, even individuals in rural areas tend to have higher socioeconomic status, which makes it easier to access ultra-processed products and transportation.

Despite its originality and importance, it is crucial to note that this study did not include an analysis of student physical activity, which significantly impacts individuals’ weight, waist circumference, and systemic BP. This study also did not discuss specific aspects of the dietary records of the students included in it.

Despite the limitations, it is worth emphasizing once again that this is an innovative study since it includes individuals in an extremely young age range (five to ten years old) living not only in urban areas but also in rural areas of the semiarid region of the Northeast. This area has been little evaluated in studies. The aim here is to support the adoption of measures that improve the living and health conditions of this population group, promoting greater life expectancy.

Further studies comparing the prevalence of overweight and obesity in pediatric populations from high-income countries and low- and middle-income countries and assessing differences between rural and urban areas are greatly needed.

In this study, which included children aged five to ten years from four municipalities in the backlands of Bahia, Brazil, a considerable prevalence of overweight, increased waist circumference, and elevated systemic arterial pressure was observed, particularly in the urban population. These data demonstrate the relevance of overweight and systemic arterial hypertension as early cardiovascular risk factors in pediatric populations.