Globally, adolescent overweight and obesity has increased significantly (1) and is now recognised as one of the most urgent public health challenges (2). This issue is particularly prevalent within the United Kingdom, with >30% of adolescents (aged 11–15 years) impacted by overweight or obesity (3). The negative physical (4, 5) and psychological (4–6) health implications associated with adolescent obesity are well-documented. Additionally, challenges also exist with reversing adolescent obesity, with 80% of obese adolescents likely to remain obese in adulthood (7), increasing the risk of further poor health outcomes in later life (8). Thus, determining effective preventative measures to mitigate the risk of obesity among this population is crucial to improve current and future health and minimise long-term obesity-related medical costs (9).

Less healthful dietary behaviours during adolescence, such as the overconsumption of energy-dense, nutrient-poor foods, can increase short (10) and long-term (11) obesity risk. United Kingdom adolescents’ dietary habits are of concern, with The National Diet and Nutrition Survey indicating suboptimal dietary behaviours among this population, including inadequate consumption of fruit and vegetables (12), low fibre intakes (13), excessive fat and sugar intakes (13) and higher energy intake also among those with overweight or obesity (14). As children transition to adolescents, they can become more susceptible to consuming an unbalanced diet (15) and dietary behaviours acquired during this period can persist into adult life (16). Therefore, dietary intervention during adolescence is essential to offset trends of declining dietary quality and establish healthy eating behaviours that can be sustained across the lifespan.

Adolescents are required to spend 190 days each year in school (17). Given the continuous contact time schools provide to this population, this setting represents a promising environment to deliver dietary interventions (18). School-based interventions are cost-effective (19) and offer the opportunity to reach the majority of adolescents, irrespective of socio-economic status or ethnical background (20). Moreover, adolescents’ consume a substantial proportion of their daily energy intakes in school (up to 1–2 meals per day) (21, 22). However, despite consistent efforts to determine the most effective school-based interventions to improve adolescents’ dietary intakes, outcomes remain short-term (23).

In Northern Ireland (NI), records suggest that more than half of adolescents (54–63%) typically consume school meals (provided by schools) at lunchtime (24) as opposed to a packed lunch (brought from home) or sourcing items from nearby food outlets. Mandatory food-based standards (25) are in place in NI schools to ensure pupils have access to a healthy and balanced school meal (26), which is of particular benefit to those who may have limited access to nutritious food outside school. However, although secondary schools provide healthier options compliant with the school-food standards, many adolescents continue to purchase the less nutritious items from the menu on offer (27), highlighting the need to explore alternate influential factors on adolescents’ lunchtime food choices. In addition to improved food provision, nutritional education is also compulsory in NI secondary schools (post-primary) for adolescents in Key Stage 3 (aged 11–14 years) (28), albeit, adolescents’ nutritional knowledge often has minimal impact on their food choices (29). Thus, identifying additional opportunities within the school-setting to promote positive dietary change is of importance. As pupils progress from primary to secondary education, parental control over their eating behaviours lessens and their propensity towards their dietary decisions become more independent-based (15). It is therefore pertinent to gain insight into the principal factors influencing adolescents’ school-based food choices as they develop increasing nutritional autonomy during this transitional period to optimise engagement and success of future school-based dietary interventions.

Research suggests that adolescents’ food choices within the school canteen can be influenced by various food-related factors, including available items, quality, appearance, taste, cost, value for money and peer pressure to opt for specific foods and canteen-related factors such as food hygiene, school menu and price displays, queue length and seating availability (30). More recent work has revealed adolescents’ favour take away items in the school canteen and associate ‘main meals’ as food to be consumed within the home environment (31).

In order to better understand the multiple levels of influence on adolescents’ food choices, Story et al. (32) proposed an ecological framework to consider their eating behaviours under four broad levels of influence to include individual (intrapersonal), social environmental (interpersonal), physical environmental, and macro level to aid in the design of appropriate nutrition interventions targeted at this population.

The difficulties associated with changing health behaviours are well recognised (33). When designing interventions, early involvement of stakeholders and the target user is recommended (34). In addition, although often under-utilised, qualitative research methodologies may assist in informing and optimising the design of interventions (35). Gaining further understanding of NI adolescents’ perspectives on the factors influencing their food choices within school and their suggestions on how best to address these factors through school-based strategies is needed if effective interventions to enhance positive dietary behaviours in this population are to be achieved. Additionally, a paucity of information exists on United Kingdom school staff’s perspectives on adolescents’ school-based food choices and their recommendations for improvement, limiting the ability for comparisons between key stakeholder groups to be examined. Furthermore, to aid in successful intervention design, consulting with school staff may provide researchers with a better understanding of any existing implementation practicalities to consider, such as schools’ academic priorities, available resources and the need to avoid over-burdening staff (36).

The aim of this study was to explore the primary factors influencing adolescents’ food choices within the school canteen environment from the pupil and school staff perspective. Additionally, a secondary aim was to identify feasible strategies to encourage healthful food choices amongst adolescents within the school-setting.

This study explored pupils’ (aged 11–13 years) and school staff’s perspectives on the main factors influencing adolescents’ canteen-based food choices and how best to encourage this population to select healthier food items within this environment. This qualitative research has identified several influential factors on food choices and recommended strategies for improvement to consider when designing future school-based interventions aiming to facilitate positive dietary behaviours among adolescents that are both acceptable to the target population and viewed as feasible for implementation by key school staff members.

In this present study, both pupils’ and school staff cited habitual intakes and personal preferences as important determinants of adolescents’ food choices within the school canteen. Food appearance and perceived taste were also identified as particularly salient factors, which can act as deterrents to selecting the healthier items available in the canteen. These findings support recent research by Glabska et al. (47) whereby adolescents considered sensory appeal of higher importance than health when determining food choices. Moreover, taste has consistently been identified in the literature to motivate adolescents’ school-based food choices irrespective of gender or location (30, 48–52). Opportunities to sample items served in the school canteen free of charge was a strategy proposed by participants in the present study, which aligns with previous United Kingdom research (53) reporting that 9–10-year-old advocated for exposure to new foods through school ‘taster sessions’.

The influence of queues on United Kingdom adolescents’ food choices in the school canteen has been reported from the early 2000s (38, 54). Results from the present study confirm that queue length remains a prominent factor when making dietary decisions in the school canteen. Data from the present study also identified that long queues can negatively influence adolescents’ food choices, and in line with previous studies in the United Kingdom (55) and further afield (56), can act as a barrier to school meal uptake, with pupils’ often sacrificing their school lunch due to long waiting times. Thus, efforts to alleviate the impact of queue length at lunchtime, such as implementing staggered breaks for different year groups or, as suggested in the present study, providing queue skips as a reward for healthy eating, may be measures for schools to consider to both encourage the uptake of school meals and establish healthier dietary habits within this environment. Findings from the current study also correspond with past research (57) that adolescents’ can be more inclined to opt for the grab-and-go options available in the canteen. As grab-and-go foods tend to be ultra-processed with typically high fat, sugar and salt contents (58), it is important that schools provide alternate nutritious, readily available grab-and-go options to support healthy school-based food choices.

In accordance with previous literature, highlighting the influential role of peer social conformity in influencing adolescents’ dietary intakes (59), the present study further evidences that peer acceptance is also fundamental when considering food options in the school-setting, which can impede the selection of healthier items. Recent work has highlighted gender differences among this age group, with females having larger concern for peer perceptions than males in relation to their dietary behaviours in school (60, 61). Interestingly, these gender disparities were not apparent in the present study, with both male and female pupils reporting feeling conscious and subject to disapproval from their peers if they opted for the healthier options, directly impacting their food choices in the school canteen. Given the perceived impact peers pose on purchasing decisions, school staff in the present study proposed involving peers in school-based strategies to promote positive dietary behaviours and particularly emphasised the opportunity to utilise senior peers in healthy eating school-based initiatives. In Australia, senior pupils have proven effective in role modelling healthful behaviours among the younger pupils in secondary school (62). Additionally, in America, a peer-led, school-based nutrition education intervention among adolescents was positively viewed and reported as feasible and acceptable among pupils, peer-leaders and teaching staff, with peer-leaders also citing improved dietary practices and awareness of healthy eating as a result of their role (63). However, the feasibility and acceptability of delivering a peer-led, school-based dietary intervention in secondary schools across NI is unknown, and thus, further investigation is warranted.

Whilst peers appear to have a significant role in influencing adolescents’ school-based dietary behaviours, school staff in the present study also cited the importance of home and parental influences in helping school’s shape adolescents’ dietary practices and were of the opinion that ‘we can only do so much’. This is comparable to an English study where secondary school headteachers and chairs of governors viewed parents as key influencers on adolescents’ lifestyle habits and that any measures taken by schools to improve these behaviours can either be supported or impaired by the home environment (64). Contrary to previous research (65), pupils’ in the present study did not acknowledge their parents or their home environment as an influential factor on their food choices in school, which may reflect how this population group place greater importance on expressing their own individual autonomy at this life stage. Future work to determine NI parents’/guardians’ perspectives on both their own and the school’s responsibilities in influencing adolescents’ food choices within the school-setting may be worthwhile.

Ultimately, participants in this study cited that adolescents’ food choices are influenced by what is available to them. In NI, assisted by a checklist, individual schools are required to self-monitor their compliance with the school food standards (66). In a recent study, NI stakeholders’ commented that adherence to the school-based standards may be negatively impacted due to a lack of monitoring (15), thus, implementation of a systematic monitoring process or procedure may be beneficial to enhance the provision of nutritious foods across NI schools.

Based on findings from the present study, pupils would welcome more frequent information on school meal choices on the menu and food prices, which would assist with pre-planning their meals. In addition to suggesting improvements to menu and pricing information, some pupils advocated for a pre-order lunch system, which has been previously shown to increase the selection of fruit, vegetable and low-fat milk items among youth in US school canteens, however, more research is required with larger sample sizes and in alternate locations to generalise these findings (67).

Incorporating labelling schemes for items served in the canteen was a leading strategy recommended from both pupils and school staff to improve food choices. Pupils and staff suggested visual labels, with pupils placing emphasis on the usage of icons and symbols. This suggestion supports previous research (68) which showed subtle messaging around foods was more impactful than explicit messaging, with adults more likely to select healthier items labelled with a heart logo than those with labels stating ‘a healthy choice’. Discussions with pupils and school staff also indicated the potential usage of colour-coded labels including traffic-light labels. A study conducted in secondary schools in Belgium found that increasing the number of healthier beverages available and applying a traffic-light labelling scheme to all items, effectively reduced adolescents’ consumption of sugar-sweetened beverages (SSB’s; labelled red) in both the school canteen and vending machine (69). Nonetheless, the importance of consultation with catering staff in individual schools prior to the design and implementation of labelling schemes was acknowledged in the present study to ensure feasibility with caterer’s daily routines, which aligns with previous research (70) reporting that school staff’s time constraints acts as one of the most dominant challenges to the implementation of school-based healthy lifestyle programmes.

Both pupil and school staff participants had a level of awareness of how adolescents’ food choices can be dependent on the location of items in the canteen, hence, manipulating the placement of the healthier options to more visible and accessible locations was a desirable concept among both stakeholder groups. Placement manipulations are a form of ‘nudge intervention’ which are generally minimal cost to implement (71). Implementing placement manipulations has resulted in increased and decreased purchases of fruit pots and SSB’s/sweet-baked goods, respectively, within United Kingdom secondary school canteens, albeit the evidence was limited (71). Further, school staff perceived items positioned first in the canteen serving area can directly impact adolescents’ food choices, and therefore, proposed serving the healthier items first as an effective strategy to improve food selection. This strategy has proven effective in breakfast buffet lines, with >75% of individuals opting for the first items they encountered (72), which could be easily transferred for implementation within school canteens.

The concept of receiving rewards to engage adolescents’ in healthy food-related behaviours in the school canteen has been positively viewed as a suitable strategy among socially deprived NI adolescents (aged 11–12 years) (30). Our findings in this study address a gap in the literature by further confirming the acceptability and feasibility of reward schemes (social, financial and recognition rewards) as incentives to promote positive food choices in school from the perspectives of both adolescents and school staff from a range of socio-economically diverse schools located in numerous district locations across NI. Tangible and praise rewards have previously proven effective in achieving positive food choice change by increasing fruit and vegetable consumption among elementary school children, although tangible rewards were more effective in the short and longer-term (73).

Overall, in line with a recent review (74), this qualitative study has identified various influential factors impacting adolescents’ food choices in secondary school canteens, with many also acting as barriers to the selection of the healthier food items in this setting. Moreover, similar to previous research with key school stakeholders outside the United Kingdom (75, 76). Participants in the present study perceived schools to be a viable setting to nurture healthy eating habits in adolescents and had clear ideas on practical and acceptable solutions, which could be implemented to better support adolescents making improved food choices in the school environment.

Collectively, this research highlights the complexity of the multilevel factors which influence adolescents’ food choices within the school canteen and identifies barriers to achieving healthier dietary behaviours. Involving pupils and school staff to explore these barriers has highlighted a number of possible practical solutions to improve food choice in school, in particular those that are low-cost and non-labour intensive. Using the ecological framework, suggestions for improvement of food choices were identified at the individual (e.g., rewards), social (e.g., pupil-led initiatives), physical (e.g., labelling) and macro environment (e.g., whole-school approaches) level. At macro level, it is recommended that schools may wish to review the pricing policy to consider offering for example meal deals or special offers, with clear menu and labelling strategies to improve information for pupils at the point of purchase and also consider the location and placement of foods on sale. Additionally, it may be beneficial to implement a whole-school initiative, for example, healthy eating days/themes in the canteen to encourage all pupils to make healthier choices. This study highlights the importance of early consultation with school stakeholders to identify the existing influential factors on adolescents’ school-based food choices and which strategies are viewed as both acceptable to the target population and suitable for implementation within the school-setting by key school staff members which should be considered in future intervention design. Further research is needed to determine the feasibility of implementing these intervention strategies within the school-setting and to test their effectiveness in practice.

The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.

The studies involving human participants were reviewed and approved by Ulster University Research Ethics committee FCBMS-20-016-A; REC/20/0031. Written informed consent to participate in this study was provided by the participants' legal guardian/next of kin.

LD, AH, and AG: conceptualisation, data coding, data analysis, and interpretation of findings. LD, AH, SB, and AG: methodology. LD and SB: recruitment. LD conducted the interviews and focus groups and drafted the manuscript. AH, SB, and AG critically reviewed the manuscript. All authors contributed to the article and approved the submitted version.

This study was undertaken as part of a PhD scholarship (LD) funded by the Department for the Economy (DfE).

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.