Table 2.

Characteristics of school food waste reduction interventions included in this review.

Author, Year and Location	Intervention Category	Sample Characteristics/Data Source	Intervention	Intervention Duration	Evaluation Design	Intervention Group	Comparison or Control Group	Outcome(s) Related to Sustainable School Food Systems	Main Findings
1. Boulet et al., 2022 [48] Australia	Food waste reduction	Primary school children aged 5–12 and their parents from Australia in schools where students typically bring food from home.	Educational intervention for children and parents encouraged to involve children in packed lunch preparation to avoid waste. The intervention comprised: lessons for students, parent information and lunchbox ideas, hands-on workshop and ‘make your own lunch’ day.	6 weeks	Pre–post	Pupils (n = 775) and their parents from five schools (n = 4)	No control group	(1) Food waste (overall number of avoidable food waste items in packed lunch); (2) Self report eating of ‘all’ food at school (%); (3) Parental attitudes (qualitative methods).	(1) Pre: 218 avoidable items; Post: 141 avoidable items post; Self-report eating of all food at school. (2) Pre: 57.3% eating ‘all’ food; Post: 63% eating ‘all’ food; (not significant). (3) Greater interest and involvement of children in choosing and making food to take to schools—parents paid more attention to what they were providing to their children.
2. Vidal-Mones et al., 2022 [31] Spain	Food waste reduction	Pupils aged 3–18 from schools in Spain where students are in charge of setting the table and tidying it when they finished eating. All schools served three courses: first course (vegetables, pasta rice or legumes), second course (protein + salad, vegetable sauces or potatoes) and dessert (fruit or dairy product).	Three nudging strategies were designed and implemented: (1) letting students know the menu on the day before lunchtime (for cases 1 and 2); (2) making students reflect on their hunger level (for cases 1, 3 and 4) and (3) teaching students how to properly cut and eat fruits (for cases 1 and 2).	10 days	Pre–post	5 schools	No control group	Total food waste (kg)	Pre: 20.58 kg across all schools Post: 13.27 kg across all schools (significant reduction of 41%)
3. Malefors et al., 2022 [32] Sweden	Food waste reduction	Pupils aged 6–19 from schools in Sweden where food is served by a public catering organisation.	Four food waste strategies selected by public catering managers were tested: (1) Information campaign directed at school children; (2) Tasting spoons in canteens; (3) Plate waste tracker providing live feedback on how much food has been wasted; (4) Forecasting for canteens to help gauge attendance.	7 weeks	Pre–post with comparator	8 schools	Reference group (n = 7 schools)	Food waste for each strategy tested (g)	Awareness campaign: pre: 37 g; post: 24 g (significant reduction of 35%). Tasting spoons: pre: 27 g; post: 21 g (significant reduction of 22%). Plate waste tracker: pre: 19 g baseline; post: 12 g (37% reduction but not significant). Forecasting: pre: 69 g; post: 35 g (significant reduction of 49%). Reference group: pre: 58 g; post: 41 g (significant reduction of 38%). Only the awareness campaign and forecasting achieved greater plate waste reduction than the reference group.
4. Rigal et al., 2022 [37] France	Food waste reduction	Pupils aged 15–19 from schools in France with on-site cooking facilities, offering three or six starters in a self-service format, in which students serve themselves freely.	Different number of starters (first course of the meal or “entree”) offered at school lunch (three vs. six) at two time points (T1 and T2) to see which resulted in the most food waste.	School lunches offered at two time points	Cross-over trial with repeated measures: T1 (baseline), T2 (T1 + 21 days)	Pupils from six senior high schools (n = 247 pupils)	3 vs. 6 options of starter	Food waste (g)	Three starters: 47.58 g ± 7.35. Six starters 75.68 g ± 9.52. Increase of 28.10 g.
5. Anton-Peset et al., 2021 [30] Spain	Food waste reduction	Primary school children from one school in Spain with a mid-morning snack brought from home and lunch managed by a catering company.	Forty-five-minute teaching sessions including fifteen activities carried out to train pupils on the food waste concept and inform them about its impact.	3 weeks	Pre–post with comparator	Pupils from one primary school class (n = 15)	Nursery (n = 48 children) and the rest of the school (n = 100 children)	(1) Food waste (g/%); (2) Knowledge and attitudes: pre–post survey and qualitative methods.	(1) Intervention group: pre; 177 g/47.83% post; 101 g/32.95% post (reduction of 14.88%). Nursery group: pre; 87 g/23.30% post; 81/26.48% (reduction of 3.18%). Rest of school: Pre; 164 g/43.76% post; 130 g/42.85 post (reduction of 0.91%). (2) Knowledge and attitudes: subtle pre–post changes including an increase in identification of food waste concepts.
6. Elnakib et al., 2021 [46] USA	Food waste reduction	Primary and middle school children in the USA where meals are provided on-site.	Lunch time staff trained on how to reduce food waste in schools. Lunch time staff then selected strategies to be tested in their respective schools. Strategies included: offering both hot and cold vegetables, offering dips with cut raw vegetables, offering sliced or cut fruit and improving the lunchroom atmosphere.	4 weeks	Pre–post	Pupils from 15 schools	No control group	(1) Number of strategies implemented in each school (Mean and range); (2) Food waste (%).	(1) Number of strategies: Mean: 7.40 ± 6.97 SD; Range: 0 to 28 delivered consistently in each school; (2) Food waste: Significant pre–post reduction of 7.01% (β = −7.061, p < 0.001).