OKkio alla Salute is an ongoing, population-based survey, conducted every 4 years, that monitors the health and health-related behaviours of primary school children across all 21 Italian regions. It is coordinated by the Istituto Superiore di Sanità - Italian National Institute of Health (ISS), with the collaboration of regional health authorities and the Ministry of Education and Merit. The target population consists of third-grade primary school children, typically aged 8 to 9 years. Italy also contributes these data to the WHO European Region’s COSI (1), enabling international comparisons on children’s health behaviours and nutritional status.

The sampling strategy follows a stratified cluster design, as recommended by the WHO (15), using school classes as the primary sampling unit. Sample selection is carried out at the Local Health Units (LHUs) level, based on lists of third-grade classes of all public and public-private primary schools provided by regional school authorities. For each school, the probability of having their classes extracted is proportional to the number of third-graders enrolled. All children in selected classes are invited to participate. Regions may choose to design samples that are representative of either the entire region or individual LHUs. Sample size calculations are based on previous estimates of excess weight prevalence, aiming for a precision of 3% at regional level and 5% at LHU level. These estimates are further refined by adjusting for design effects observed in previous survey waves.

Data collection involves three sets of questionnaires, completed by children, their parents or caregivers, and school principals (Supplementary Table S1), alongside direct anthropometric measurements of weight and height taken by trained healthcare staff. The detailed survey protocols and data collection procedures are described elsewhere (16, 17).

The HBSC survey is an international, multicentre study conducted every 4 years in collaboration with the WHO Regional Office for Europe. In the 2021/2022 round, the survey was implemented in 44 countries and regions across Europe, Central Asia, and Canada. In Italy, the 2022 edition was coordinated by the ISS and the Universities of Turin, Siena, and Padua, with support from both the Ministry of Health and the Ministry of Education and Merit. The HBSC targets adolescents aged 11, 13, 15, and 17 years, capturing data on self-reported anthropometric measures (weight and height), lifestyle behaviours, health outcomes, and social and school environments (3).

The sampling follows international HBSC guidelines and employs a systematic cluster sampling method. School classes serve as the primary sampling unit, and the selection is based on national lists of schools provided by the Ministry of Education and Merit. As with OKkio alla Salute, students and school principals complete standardized questionnaires (Supplementary Table S1). Additional details regarding the sampling methodology and data collection process are available in Inchley et al. (18).

Both surveillance systems (OKkio alla Salute and HBSC) operate under strict ethical standards. The study protocols for OKkio alla Salute and HBSC were reviewed and approved by the Institutional Ethical Board of the ISS.

The present study examines how a school environment that self-assesses as supportive is associated with selected lifestyle indicators among children and adolescents.

School environment information was derived from the school principals’ questionnaires in both surveys. In the case of OKkio alla Salute, we evaluated the presence of school health promotion practices related to healthy eating and PA, including curricular programs and projects involving parents or LHUs. The HBSC survey assessed whether schools adopted health promotion policies or guidelines, and whether curricular activities on nutrition and PA were present. Information on timing, duration, intensity, implementation fidelity and content of the reported practices was not collected.

Lifestyle data included indicators related to weight status, dietary habits, PA, and sedentary behaviours. Body Mass Index (BMI) was calculated for each participant using measured (OKkio alla Salute) or self-reported (HBSC) height and weight, and categorised according to the age and sex-specific international thresholds developed by the International Obesity Task Force (IOTF) (19, 20). Based on these thresholds, children and adolescents were classified as underweight, normal weight, overweight, or obese.

Dietary habits among younger children (OKkio alla Salute) were assessed through questions on consumption of: (1) breakfast, classified as no, yes/inadequate, yes/adequate; (2) mid-morning snack, classified as no, yes/inadequate, yes/adequate; (3) fruits and/or vegetables ≥5 times a day (yes/no); (4) sugary and/or carbonated beverages every day (yes/no). Breakfast and mid-morning snack quality were determined using criteria established by the Centre for Research on Food and Nutrition (CREA) (21), with “adequate” breakfast defined as one containing proteins, complex carbohydrates, and simple carbohydrates. Mid-morning snacks were considered adequate if they included healthy items such as fruit, yogurt, or unsweetened juice and provided around 100 calories. Children were asked to recall what they had consumed that morning to determine dietary quality, following the framework established by Ciardullo et al. (22).

In the HBSC survey, dietary habits were captured via adolescent self-reports. Relevant indicators included: (1) breakfast consumption during the school week (yes/no); (2) fruits consumption (≥ once a day); (3) vegetables consumption (≥ once a day); (4) daily consumption of sugary and/or carbonated beverages (yes/no).

PA habits were also analysed using age-appropriate indicators. In OKkio alla Salute, children reported whether they had been physically active (sports, outdoor play or PE at school) in the last 24 h, and parents reported whether their child had engaged in outdoor play or sports the day before the survey and if the child habitually walked or cycled to school. HBSC assessed adolescents’ PA levels through questions on moderate and vigorous exercise, based on WHO recommendations (23). Adolescents were asked about the frequency of (1) moderate PA for at least 1 h, on a scale of 1 to 7 days/week, and (2) vigorous PA (substantial increase of heart and breathing rates), on a scale of 1 to 7 days/week.

Sedentary behaviours were captured in both surveys through questions on screen time. Parents reported how much time their child typically spent watching TV, playing video games, or using digital devices on a school day. This information was categorized into two groups: ≤2 h or >2 h, consistent with WHO recommendations (23). The questionnaire also included a question on the presence of a TV in the child’s bedroom, as this has been linked to reduced parental oversight (24).

Socioeconomic status (SES) was also considered. In the OKkio alla Salute survey, the mother’s education level served as a proxy for family SES, a measure commonly used in public health research for its strong association with children’s health outcomes (25). In the HBSC survey, SES was measured using the Family Affluence Scale (FAS), which captures material wealth and family lifestyle. The FAS includes items such as car ownership, number of computers, availability of a dishwasher, private bedroom for the adolescent, number of bathrooms, and frequency of family vacations abroad (26).

Due to the differences in sampling strategies, measurement methods (measured vs. self-reported anthropometrics), age groups, and years of data collection, the data on children and on adolescents are not directly comparable. Therefore, results are interpreted within each surveillance framework rather than comparatively, and conclusions focus on patterns observed within each dataset.

Descriptive analysis used frequency and percentage for categorical variables, median and interquartile range for continuous ones. The Chi-square or the exact Fisher test was performed to evaluate associations between two categorical variables, as appropriate. p-value < 0.05 was considered statistically significant. SAS software 9.4 (SAS Institute Inc., Cary, NC, USA) was used for statistical analysis.

The results indicate that overweight and obesity remain prevalent among school-aged children and adolescents, particularly among boys, thereby confirming previous national and international findings. Our prevalence data are in line with those from the other northern Italian regions and show a substantially lower prevalence of excessive weight compared to southern Italy, confirming the national north–south gradient (2, 27–29).

Adolescence represents a critical developmental stage that marks the transition from childhood to adulthood and is characterized by profound psychological, biological, and hormonal changes, as well as significant shifts in social roles (30, 31). In line with prior reports, our findings indicate a decline in the prevalence of overweight and obesity from pre-pubertal to pubertal stages (8, 27, 32). Although self-reported anthropometric measures among adolescents may be underestimated as a result of reporting and social desirability biases (33–35), our results are consistent with national (36) and international studies (37).

The decrease in overweight and obesity prevalence may be due to hormonal changes that occur as boys and girls approach puberty (38). In addition, teenagers tend to pay more attention to their physical appearance and to put more effort into controlling their weight. Increased stress and pressure associated with middle and high school may also contribute to weight loss in this age group (39). In terms of differences in BMI categories between males and females, the higher prevalence of overweight and obesity in males we observed is consistent with previous literature (40).

While among younger children daily breakfast consumption was high and in line with comparable Italian (22) and international contexts (41), it sharply declined in adolescence, confirming a concerning trend that is already well documented in the literature (3, 29). Daily consumption of fruits and vegetables remains critical in children and low among adolescents. This is in line with the WHO-HBSC 2022 report (3), and with findings across Europe that highlight widespread challenges in meeting the recommended dietary guidelines (42).

PA levels among younger children are high, yet only about half regularly participate in sports. Active commuting to school is limited, the main barriers reported by parents being excessive distance to school, lack of parent’s time and road safety issues. The cross-sectional nature of our study does not allow us to assess the role of existing school initiatives in influencing the behavioural patterns described above. However, our findings can point to areas where school-based strategies could be further developed to support daily PA but also highlight missed opportunities, such as initiatives to promote walking and cycling to school with well-documented benefits for both health and sustainability (11). Among adolescents, over half fail to meet recommended levels of moderate-intense and vigorous PA, which is consistent with European surveillance data. Disparities between sexes also align with global trends, with higher inactivity among females (43, 44). These differences underscore the relevance of gender-sensitive approaches identified in previous literature (45, 46), although the present study does not address the potential benefits of such approaches.

Our results underscore the role of schools health promotion: with most of the FVG primary schools integrating nutrition and PA education in their curricula. However, these activities are largely delivered by classroom teachers, and the involvement of external professionals or stakeholders, particularly LHUs, is lower than the average of the other regions of Northern Italy (12% vs. 16.7%) and of the national data (23.5%) (2). This approach reflects the Regional strategy that prioritizes teacher-led implementation to ensure equity and universal access, as reported in the Regional guidance documents (47). The limited contribution of external stakeholders should therefore be seen as an executive choice rather than an organizational shortcoming.

In our sample, parental engagement in school initiatives is limited, but where present, it is associated with a higher proportion of primary school children consuming an adequate mid-morning snack (p < 0.001). While this association cannot be interpreted as causal evidence that parental involvement directly drives behavioural change, it aligns with the existing literature that suggests that active parental involvement can enhance the effectiveness of school-based interventions targeting children’s dietary behaviours (48, 49).

A nuanced picture emerges from the HBSC data regarding school policies. Only a minority of schools report having written policies for promoting healthy eating and PA, while a larger proportion rely on unwritten guidelines. This reliance on non-formalized approaches may be associated with variability in the consistency, accountability, and reach of school-based practices. Previous studies suggest that structured, written policies are more likely to be implemented into the school setting (7).

Student involvement in shaping health promotion initiatives is relatively high in FVG. This is a positive finding, as youth engagement is recognized as a key determinant in the success of school-based health promotion programs (50). However, further investigations are needed to understand whether students are engaged through meaningful participation or more symbolic involvement.

Across both surveys, most student behaviours and weight-related outcomes did not differ significantly according to the presence or absence of reported school practices or policies, except for an increased prevalence of adequate mid-morning snacks in children when parents are involved in healthy eating school-based initiatives. However, the absence of statistically significant associations in our data does not imply that school health promotion strategies are ineffective; rather, it likely reflects the heterogeneity of practices and policies across schools, the use of binary exposure classifications, the lack of information on implementation fidelity or duration, potential residual confounding, and the limited sensitivity of cross-sectional surveillance data to detect small effects in the absence of temporal sequencing.

Based on the literature, interventions that yield significant impact, typically include a combination of actions aimed at increasing PA, decreasing sedentary behaviours, and improving dietary habits (51) and involve parents through workshops, take-home activities, and regular communication (52). The duration of interventions also appears to play a relevant role. There is, in fact, evidence supporting interventions lasting at least an entire school year that include multi-sectoral collaboration, parental engagement and clear policy frameworks (14, 53–55).

A major strength of this study is the large and representative sample of both primary and secondary school students, which allows for robust comparisons and generalizability within the region. Moreover, the study provides descriptive evidence on the presence of specific school interventions and their relationship with health-related behaviours, although these findings cannot be interpreted in causal terms.

Our study needs to be interpreted in the light of some limitations. First, the cross-sectional design of the study precludes inferences regarding temporal ordering or causality. Second, the structure of the questionnaires did not allow to obtain detailed information on the types of programs and their contents, and the variability in intervention intensity and implementation quality across schools was not systematically measured. Consequently, exposure measurement was necessarily coarse and potentially affected by misclassification, which may have contributed to few statistically significant associations, such as the low prevalence of children that consume fruits and/or vegetables ≥5 times a day.

In addition, the use of self-reported data, particularly among adolescents, introduces potential reporting biases, especially for sensitive variables like body weight, PA and sedentary behaviours. In addition, since the two surveys were designed to target different age groups, some questions were worded differently, and this may have further accentuated the differences observed between the two populations. Lastly, while it is likely that the relatively low level of collaboration with parents and LHUs reported by most schools may have limited the scope of the school-based activities, the observational design of our study does not allow to determine the extent its influence on the behaviours observed.