Objectives

The objectives of this study are as follows:

Main Objective

Development of a Proposed Solutions Box for Improving Nutritional Behaviors of Iranian Female School Students

The Specific Objective of the First Phase (Qualitative Study)

1. -  Explaining the preventive nutritional perception, experience and behaviors of female school students based on Social Cognitive Theory (SCT)

The Specific Objective of the Second Phase (Quantitative Study)

1. - Prioritizing of extracted solutions from phase one (the nominal group method)
2. - Sequencing prioritized solutions (the scoring technique in pairwise comparisons)

The Specific Objective of The Third Phase of research (Solutions Optimization)

1. - Creating Matrix for the Solutions
2. - Providing an Action Plan for fixed solution
3. - Visualization of Solutions Box

Study design

A mixed-methods study with a sequential exploratory design will be conducted, following Creswell’s framework [26]. This design involves two distinct phases:

Phase 1 (Qualitative): Semi-structured interviews and directed content analysis to explore the subjective experiences and contextual factors influencing nutritional behaviors.

Phase 2 (Quantitative): Prioritization and ranking of solutions identified in Phase 1 using quantitative methods. The philosophical foundation of this research is pragmatism [27]. This approach benefits the study by prioritizing practical outcomes and enabling the integration of qualitative insights (e.g., cultural barriers, personal experiences) with quantitative data (e.g., solution prioritization) to develop context-specific, actionable strategies (the solution box). Pragmatism aligns with the study’s goal of addressing real-world nutritional challenges through a problem-centered, flexible framework. In this way, high-quality and rich information can be obtained to explain the concept and dimensions of preventive nutritional behaviors from the experiences of participants. Therefore, after a comprehensive literature review data will be collected through semi-structured interviews according to four constructs of SCT and will be analyzed by directed content analysis. The steps of the study design have been illustrated in Fig 1 (Fig 1).

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Fig 1. Study Design of Development of a Proposed Solutions Box for Improving Nutritional Behaviors of Iranian Female School Students.

https://doi.org/10.1371/journal.pone.0329671.g001

Literature review

The study is designed to identify and analyze the existing body of literature related to preventive nutritional perception and behaviors among female school students. This critical analysis is an essential part of the research process, as it helps establish what is already known about the topic and identifies gaps or further questions that the research aims to address. The literature review will focus on five key areas:

1. Preventive Nutritional Behaviors: We will search for relevant literature using keywords, concepts, theories, authors, and studies related to preventive nutritional behaviors in school students. This includes identifying factors influencing dietary habits and barriers to healthy eating.
2. Best Practices and Interventions: We will review literature on evidence-based interventions and best practices for improving nutritional behaviors in school students, with a focus on culturally appropriate strategies.
3. Theory of Change: We will explore literature on effective theories of behavior change, particularly those applicable to nutritional behaviors in adolescents.
4. Social Cognitive Theory (SCT) Constructs: We will identify and analyze predictive constructs of SCT (e.g., self-efficacy, observational learning) that are relevant to nutritional behaviors.
5. National Guidelines: We will review national guidelines and policies related to strategies and solutions for improving nutritional behaviors in school students, ensuring alignment with local context and priorities.

By synthesizing these areas, the literature review will provide a comprehensive foundation for the study and inform the development of the solution box.

The ultimate goal of this literature review is to identify gaps in current knowledge and inform the development of effective, context-specific solutions for improving nutritional behaviors among Iranian female school students. Furthermore, the outcomes of the literature review will elucidate which among the nine constructs of SCT yield predictive constructs of preventive nutritional behaviors. Consequently, predicated on these identified constructs derived from the comprehensive literature review, the guiding questions for the qualitative study will be formulated during the first phase of the research. This approach ensures a robust and informed foundation for the subsequent phases of the study.

The first phase of the research: Qualitative study

In phase one, to align with the theoretical framework of Social Cognitive Theory (SCT), we selected directed content analysis as the most appropriate qualitative method for this study. SCT emphasizes the dynamic interplay between personal, behavioral, and environmental factors, and directed content analysis allows us to systematically analyze data through the lens of predefined SCT constructs (e.g., self-efficacy, observational learning, outcome expectations, and behavioral capability). This method ensures that the analysis remains anchored in SCT’s theoretical principles while still capturing emergent themes from participants’ lived experiences.

Characteristics of the study population and participants

In this research, the primary participants (female school students) and secondary participants are stakeholders (school parents, parents of students, and health policy makers). The research will be selected with the purposeful sampling method, which is suitable for qualitative research [28]. In this method, the researcher is looking for people who are a rich source of information and can express themselves and their desire to participate in the research. Sampling and data collection will continue until the information saturation level is reached, that is, when the participants do not add new data to the previous data and the previous data are repeated [29].

Method of data collection

The data collection method at this phase will be a semi-structured interview. At this stage, the first researcher (NM) as an experienced healthcare provider will be present in Secondary schools of Andimshek city, one of the big cities of Khuzestan province. Schools were selected using purposeful sampling to ensure representation across urban, semi-urban, and rural zones, as well as varying socioeconomic status (SES) levels. Participants (female students, parents, and stakeholders) were selected using stratified purposeful sampling to reflect diversity in age, education level, SES, and cultural background. Recruitment continued until data saturation was achieved. After introducing herself, explaining the importance and objectives of the research, and gaining the trust of the participants, written information which was approved by the ethics committee of Tarbiat Modares University and verbal consent will be obtained from the parents of students and the stakeholders, respectively. The time and place of the interview will be coordinated with them. Data will be collected using digital voice recorders and transcribed verbatim. Recordings will be stored on password-protected devices and encrypted to ensure confidentiality. The interview will be conducted individually and in a private and quiet environment desired and approved by the participants. The interview will begin with open-ended questions that allow the participants to fully describe their experiences of the phenomenon in question. At the beginning of the interview, questions will be asked to familiarize the researcher with the participants and also to create a sincere atmosphere, and as the interview proceeds, they will be guided to specialized questions in line with the research objectives (Table 1).

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Table 1. Interview guide questions based on the main constructs of the Social Cognitive Theory.

https://doi.org/10.1371/journal.pone.0329671.t001

After the participant answers each of these questions, probing questions will be asked appropriately and the interviews will continue until the participants believe that they have no more information to provide. In case of fatigue or lack of data saturation of the data, the interview will continue in the next sessions with the same participant. At the end of the interview, the participants will be asked to state if there is anything else left. Then, while thanking the participant, the possibility of needing an interview or the next question is raised. In addition to audio recording, the researcher will record all emotions, facial changes, tone of voice, etc. during the interview with a pen and paper. After the completion of the interview, the recorded items will be played carefully as soon as possible. The original interviews will be kept in confidential folders. Analysis and initial coding of the data of each interview will be done before the next interview. After conducting the interview, the text will be presented to the supervisors and the necessary guidance will be obtained to improve the next interview process.

Data analysis

To answer the research questions and analyze the data, the qualitative content analysis method will be used. To analyze data in the first step of phase one (qualitative study), the content analysis method will be used with a directed (deductive) approach. The analysis process will be done simultaneously and continuously with the data collection and based on the approach proposed by Shannon and Hsieh, through qualitative directed content analysis [28]. Directed content analysis, as described by Shannon and Hsieh, is a systematic approach used in qualitative research to interpret meaning from the content of text data. This method begins with a theory or relevant research findings that serve as guidance for initial codes. The process of directed content analysis can be summarized in the following steps:

—Selection of Theory or Texts: This initial stage encompasses the identification and examination of theories and texts pertinent to the phenomenon under study. The selection of an appropriate theory or text for the analysis of the phenomenon is a crucial part of this step.

—Extraction of Conceptual Characteristics: This step involves a thorough review of the chosen theory and related texts. The characteristics of the concepts and components of the theory, or the findings of the texts, are defined and delineated. These characteristics serve as vital information for subsequent analysis.

—Matrix Construction: A matrix is formulated wherein the concepts and dimensions identified in the previous step are arranged in columns and rows. This matrix acts as a reference framework for data analysis.

—Data Collection: Data is collected through interviews, with an interview guide prepared based on the main concepts, characteristics of the concepts, and definitions presented in the matrix. The collected data serves as the primary source for further analysis [28]

—Selection of Semantic Units and Code Extraction: Semantic units are selected from the data and codes are extracted for them, guided by the main research question and the concepts defined in the theory. These codes function as key markers for the data.

—Code Placement in the Matrix: The extracted codes are positioned in the matrix prepared in step 3. This step facilitates the alignment of the data with the defined concepts and enables a more detailed analysis.

—Operational Definitions for Main Concepts: Operational definitions for each of the main concepts of the theory are provided by comparing the codes and results obtained from the data analysis with the theoretical definitions in the matrix. These definitions aid in the precise interpretation and scientific analysis of data [28].

It enables the researchers to examine the phenomena under scrutiny scientifically and in details for better comprehension. Besides, this approach may be used as a tool of shaping or amending predefined theories and concepts.

Accuracy of the findings

To validate the findings of this research, Johnson’s five criteria, which include credibility, confirmability, reliability, transferability, and authenticity, will be used [30]. Credibility: We will try to ensure the validity of the data, and enough time will be allocated to collect the data. There will be a long-term engagement with the data and immersion. Also, by combining data sources and theories, sampling from different comprehensive schools located in different zones of the city of Aandimeshk, the maximum diversity in sampling will be observed. Confirmability: For this reason, the researcher will try to describe all the stages of the research including data collection, analysis, and extraction of codes and classes in such a way that other people will be able to judge the correctness of the data by reading them. After writing the text, the co-researcher, who did not participate in the data collection stage, applies the necessary changes by comparing the text with the tape. To further confirm the validity of the content, several interviews will be coded and returned to the participants and the specialist for review. To ensure verifiability, the researcher will try not to interfere with his assumptions as much as possible in the process of data collection and writing. Reliability or Dependability: The researcher will ensure the reliability of the research by performing actions such as a review by the research group and analysis of observers in the 6-month reports. Transferability: We will try to select more diverse participants (students and parents) in terms of age, education, place of residence, and social, cultural, and economic status (maximum variance), and this process will continue until data saturation. Authenticity: This will be ensured by carrying out measures such as targeted sampling and the maximum diversity of participants (Table 2).

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Table 2. Accuracy of the Data from female school students and stakeholders concerning selected SCT constructs in line with the Solutions Box development for Improving Nutritional Behaviors of Iranian Female School Students.

https://doi.org/10.1371/journal.pone.0329671.t002

The second phase of the research: Quantitative study

This step of the study design for the proposed solution box for improving the nutritional behaviors of female school students. This phase encapsulates the prioritization, weighting, and ranking of extracted context-based solutions from the qualitative phase. This phase aims to quantify the qualitative findings obtained from the first phase of the study.

Rationale for Compiling the Solution Matrix Based on Separate Theoretical Frameworks

1. Three Strategies of the Ottawa Charter in Health Promotion and Behavior Change Planning Health promotion, now more than ever, is crucial in addressing public health issues. It has been increasingly acknowledged over the past decades that biomedical interventions alone cannot ensure optimal health. The Ottawa Charter underscores the importance of addressing social, economic, and environmental determinants of health to achieve holistic well-being. Thus, achieving the highest possible health standard requires a comprehensive approach that transcends traditional medical care. This approach empowers individuals and communities to take health actions, strengthens public health leadership, promotes intersectoral action for healthy public policies, and builds sustainable health systems. Consequently, considering the strategies outlined in the Ottawa Charter can significantly enhance the planning of health behavior change interventions [37].
2. Social Determinants of Health: Considering social determinants of health in planning health behavior change interventions is essential for devising effective, equitable, and sustainable strategies. Addressing the root causes and underlying factors influencing health behaviors can significantly impact population health outcomes [38].
3. Constructs of Social Cognitive Theory: Theories can elucidate the structural and psychological aspects of behavior and guide the development and modification of health promotion and education efforts. Health behavior theories focus on behavior determinants at various levels – individual, interpersonal, group, organizational, and/or community. Integrating these theories into health behavior change intervention planning offers a systematic and evidence-based approach, increasing the likelihood of successful outcomes by addressing human behavior complexities and tailoring interventions to the target population’s specific needs and contexts [39].
4. Ecological Focus: Effective health promotion programs typically operate at multiple levels, focusing not only on at-risk populations but also on environmental conditions that significantly influence health and health behavior. This perspective acknowledges multilevel behavior effects and emphasizes interconnected systems at individual, interpersonal, organizational, and societal levels. Understanding contextual factors and modifying environments support interventions tailored to behavior change complexity. Hygienic behavior is crucial at every societal level. However, achieving health promotion goals at any societal level necessitates behavioral changes among those controlling or influencing the desired health outcomes [40]
5. Triple Levels of Prevention Attention to the three levels of prevention – primary, secondary, and tertiary – is crucial in planning health behavior change. This approach enables a comprehensive strategy, targeting root causes with primary prevention, addressing early symptoms through secondary prevention, and mitigating the impact of existing conditions with tertiary prevention. Incorporating these prevention levels allows planners to proactively address health risks, prevent disease onset, and manage existing conditions, leading to a more precise and effective approach to behavior change [41].

Ethics approval and consent to participate

All methods were carried out following relevant guidelines and regulations (Helsinki Declaration of Ethical Principles for Medical Research and Ethical Research Guidelines Involving Children (ERIC) guidelines. Ethical approval was obtained from the Ethics committee of the faculty of medical sciences, at Tarbiat Modares University (IR.MODARES.REC.1402.247).

Limitations and considerations for future research

First, the study’s focus on female school students within Khuzestan province means the resulting ‘solution box’ will be highly context-specific. This will limit the direct generalizability of the intervention itself to other cultural or regional settings. However, we contend that the primary contribution is the methodology—a replicable, bottom-up framework for co-developing and prioritizing public health solutions—which is intentionally designed to be transferable and adaptable to other populations.

Second, the research will rely on self-reported data during both the initial qualitative exploration and the quantitative prioritization phases. This introduces a potential for social desirability or recall bias. To mitigate this, our facilitators will be thoroughly trained in building rapport and fostering a neutral environment to encourage candid responses from participants.

Finally, and most importantly, this protocol outlines the development and prioritization of an intervention, not the evaluation of its effectiveness. The design is not longitudinal and therefore cannot establish causal relationships between the ‘solution box’ and changes in health outcomes.

Consequently, these limitations clearly delineate the path for future research. The most critical next step will be to conduct a longitudinal controlled trial to rigorously evaluate the efficacy of the developed ‘solution box’ on measurable nutritional behaviors and clinical health indicators. Future studies could also apply our mixed-methods developmental framework to other health challenges or diverse populations, further validating its utility as a public health tool.