Purpose: Healthy dietary habits learned at a young age often track into adulthood, with a potential to induce life-long effects on overweight and related chronic conditions. School-based health-promoting interventions are increasingly seen as effective strategies to improve health and prevent obesity, but evidence on long-term effectiveness is scarce. The effects of long-term exposure to the Healthy Primary School of the Future (HPSF) on children’s dietary and weight-related outcomes are presented and implications will be discussed. Methods: The study has a quasi-experimental design with four intervention schools, i.e., two full HPSFs (focus: diet and physical activity), two partial HPSFs (focus: physical activity), and four control schools. Primary school children (aged 4-12 years) attending the eight participating schools were invited to enroll in the study between 2015 and 2019. Children’s body mass index z-score (BMIz), waist circumference (WC) and dietary behaviors (child- and parent-reported questionnaires) were measured annually. Results: Between 2015 and 2019, 2236 children enrolled. The average exposure to the school condition was 2·66 (SD 1·33) years, and 900 participants were exposed for the full four years (40·3%). After four years of intervention, both full (estimated intervention effect (B)=-0·17 (95%CI -0·27 to - 0·08) p=0·000) and partial HPSF (B=-0·16 (95%CI-0·25 to -0·06) p=0·001) resulted in significant changes in children’s BMIz compared to control schools. Likewise, WC changed in favor of both full and partial HPSFs. In full HPSFs, almost all dietary behaviors changed significantly in the short term. In the long term, only consumption of water and dairy remained significant compared to control schools. Conclusions: The HPSF is effective in bringing unfavorable changes in children’s body composition to a halt in both the short and long term. This offers policy makers robust evidence to sustainably implement the program in school-based routine. Providing healthy school lunches is feasible as long as parents, children and schools are involved in implementation. Complementing this with a continuum of dietary approaches targeting multiple aspects of children’s social, cultural, economic and physical environment throughout childhood, adolescence and towards adulthood, will optimize the impact on population health.

Purpose: As children move into adolescence, their eating habits tend to become more unhealthy. Changes in the school environment may explain this negative impact on healthy eating habits. In particular the primary-secondary school transition could influence eating habits due to changes in the social and physical environment. This study examines how the transition from primary to secondary school impacts preadolescents’ food choices by using a Self-Determination Theory (SDT) perspective.

Methods: In this longitudinal study, Dutch preadolescents were followed from their last year of primary school (T1) into their first year of secondary school (T2). A questionnaire was distributed, which was completed by 142 preadolescents with a mean age of 12.18 (SD = .43) at T1 (June 2019) and 66 preadolescents at T2 (March 2020). Due to corona, secondary schools were closed and further data collection was cancelled as the questionnaire was mainly focused on eating behaviors at school. More specifically, the questionnaire included measures on snack and beverage intake at school, food-related autonomy, competence to eat healthily, healthy eating motivation and school environmental and eating characteristics. A healthy intake ratio was calculated to indicate the relative healthiness of snack and beverage consumption within preadolescents’ total consumption. Descriptive statistics, correlations and linear mixed-effects models were conducted.

Results: Preliminary results from linear mixed-effects model analyses show that preadolescents’ healthy snack and beverage intake at school decreased when they transitioned from primary to secondary school (β = -7.31, SE = 2.84, 95% CI [-12.88, -1.73], p = .01). On average, 62.9% of preadolescents’ total snack and beverage intake at school consisted of healthy options at T1. At T2, 57.8% of their total intake was healthy. In addition, competence to eat healthily was associated with increased healthy intake ratio over time (β = 2.27, SE = 0.66, 95% CI [0.97, 3.57], p < .001). Healthy eating motivation and food-related autonomy were not associated with changes in preadolescents’ healthy intake ratio over time.

Conclusion: The transition from primary to secondary school negatively affects preadolescents’ healthy intake at school. Healthy intake decisions at school environments could be supported by targeting SDT needs.

Purpose: Traditional food marketing, mostly involving advertisement of nutrient poor and energy dense foods, has the effect of enhancing attitudes, preferences and increased intake of marketed foods in adolescents, with detrimental consequences for health. While the use of social media applications in adolescents has proliferated, little is known about the content of food promotions within these applications. The aim of this study was to investigate adolescents’ exposure to and evaluation of social media food promotions (SMFP).

Methods: Australian adolescents aged 13-16 years joined a one-on-one Zoom meeting with the researcher, on the device they normally use to access social media. Participants shared their screen and visited up to three of their favourite social media platforms while the researcher indicated SMFP examples, for 10 minutes each platform. Next, the participants answered questions about their awareness and appreciation of SMFP. Screenshots of food promotions were de-identified and analysed.

Results: The study included 35 adolescents aged 14.4 (±1.2) years (boys: n=18; girls: n=17). Instagram, Snapchat and YouTube were their most favourite social media platforms. During a total of 1000 minutes of viewing time, 1903 posts containing unbranded (n=1292) and branded (n=611) food content were identified. Participants viewed a median rate (IQR) of 13.0 (7-21) SMFP per 10 minutes, with 7.0 (3.3-12.3) SMFP containing a majority of non-core foods. A majority (67%) was embedded in celebrity influencer or entertaining content (e.g. vlogs, cooking videos, streamed TV content). More than half of participants (60%) said to have sometimes, rarely or never recognized the viewed food promotions themselves, and participants largely remembered non-core foods or (fast food) brands (77%). Almost half (49%) of participants liked SMFP, while only 6% disliked them.

Conclusions: This study contributes to a relatively unexplored research area. The outcomes show adolescents’ SMFP exposure mostly concerns unhealthy foods, shown in advertisements and other food-related posts, which are integrated into a wide variety of entertainment that is largely appreciated by adolescents. The results emphasize the need for more research on SMFP, with particular focus on the impact on adolescent dietary behaviours, and clearer definitions and stricter regulations regarding adolescent-targeted social media food marketing.