According to Principato et al. ^[1][22], consumers, companies, and institutions should cooperate to minimize food waste, which was also the argument by Baron et al. ^[2][49], who argued for a service ecosystem that is able to grasp situations where food waste becomes prominent. Viewing food waste from a societal service innovation perspective, the authors argue that the role of institutions such as retailers, producers, and authorities and their interrelations become a way to challenge the existing system with its obvious food waste issues. Packaging overlaps several links in this product–service system and plays an essential role in people’s in-store decision making ^[3][50]. Several studies have focused on how packaging can have a positive impact on reducing consumer food waste, either by prolonging shelf life, protecting food, creating awareness, or affecting home use. Based on the study by Williams et al. ^[4][26], 20–25% of wasted food in households in Sweden could be caused due to packaging functions that do not meet consumer needs, such as being too large or being difficult to empty.

Technological solutions should be mentioned in the holistic view of food waste. Various kitchen gadgets have been suggested to ease the measurement of portions (e.g., pasta and spaghetti) to prepare the optimal portion of food and to reduce possible leftovers. Other digital solutions in the form of mobile device applications have been invented to increase the visibility of food waste behavior and reflections ^[5][51], using photos of food leftovers that would go to the bin. A good example of such a solution is BinCam, which was created as a social persuasive system with the intention of motivating reflection about food waste generated at the household in a playful manner and to change food waste generation and recycling habits of young adults ^[6][52]. Generation Z is often described as digital natives, so it is expected that various applications could be an obvious tool for intervention in food waste reduction among young people.

Very few studies on food waste interventions have specifically targeted young consumers. Based on the study by Kymäläinen et al. ^[7][5], there are three ways to enhance sustainable food consumption behavior among young consumers: (1) support a shift in diet, (2) provide concrete information, tutoring, and education, and (3) encourage sustainable food consumption. This is in line with findings from Burlea-Schiopoiu et al. ^[8][36], showing that the more knowledge young students have, the higher their intention to reduce food waste. Knowledge does not need to be in the form of campaigns, as sources of knowledge are diversified and could include observed behaviors, trial and error, or peer-to-peer conversations ^[8][36].

Few studies have been conducted on food waste and nudging in the household environments ^[9][53]. According to the authors, young people and those living in large households with young people are open to changing their behavior with nudging methods. However, the respondents were mostly interested in feedback regarding their own individual behavior (quantities and financial costs), social exchange and interaction, and specific advice on meal planning.

Reynolds et al. ^[10][43] found 17 effective interventions for food waste reduction within households and institutions, with professional staff in charge of preparing and serving food. Plate size reduction at hospitals was among the most effective, followed by changes in the nutritional guidelines at schools. This is in line with findings from Kallbekken and Saelen ^[11][54], showing that reducing plate size could reduce approximately 20% of food waste in hotel restaurants in Norway, which again was outlined by Freedman and Brochado ^[12][55], showing that reducing the portion size is a way to reduce plate waste in restaurants.

The United States of America National Strategy to reduce food waste at the consumer level ^[13][56] highlighted seven intervention types that can contribute to reducing consumer food waste: (1) appealing to values, (2) engaging consumers, (3) evoking social comparison, (4) providing feedback, (5) providing financial incentives, (6) modifying the choice architecture (i.e., nudges), and (7) providing how-to information.

From these choices, architecture and social comparisons were found to be the most effective ways to influence consumer behavior. Intervention choices were based on studies that have examined consumer behavior in the following domains: energy conservation, water conservation, waste prevention/management, recycling, diet change, and weight management.

Many authors have outlined the basic limitations of intervention studies on food waste. In a study of the impact of a crisis on food waste perception ^[8][36], the authors described the effect over time as a limitation. The effect of COVID-19 on food waste could have a here-and-now effect, but it could evaporate when things become normalized. This was also the conclusion in a review by Reynolds et al. ^[10][43], who found that campaigns, cooking classes, food sharing apps, and sharing through apps influenced food waste reduction, but with very little or no robustness. The lack of reproducible and quantified interventions is a core challenge in many food waste interventions, and intervention studies with better and standardized guidelines are needed ^[14][44]. The authors describe the difficulties in making evidence-based decisions to prevent food waste as a significant evidence gap, and they see this as a barrier to change behavior.

The most common and pervasive limitation is related to the impact of the intervention on the actual amount of food wasted, as it is difficult to measure the actual amount of food wasted before and after the intervention. A method capable of measuring the exact amount of waste by weighing has been used in the garbage stream of households, cantinas, etc., but it is difficult to apply it to food waste, as it does not measure what could be poured down the drain, fed to pets, or composted ^[15][57].

Several papers cited in this study have emphasized some methodological and/or conceptual issues by not clearly distinguishing between household recycling and food waste ^[16][3]. The European Union Horizon 2020 project REFRESH ^[17][58] suggests a method for evaluating the effectiveness of interventions designed to prevent household food waste. The suggested method is based on understanding the intervention, development of the evaluation approach, dissemination, and implementation of the findings. The project report concluded that there is a need for thorough and logical mapping to outline the design of activities in the intervention and to register the final outcome. The first step was to define the aim of the intervention by answering the following questions: What does the intervention seek to obtain? Who does the intervention seek to influence (the audience)? What type of intervention is used (single/multiple or short/long-term interventions)?

Figure 12 outlines the key interventions used to reduce food waste. These interventions should be combined, keeping in mind the delicate interlinkages between them and the possible synergies when several interventions are applied simultaneously.