Design and implementation of a theory of planned behavior-based nutrition education intervention for adolescent girls in rural Nepal: a school-based cluster-randomized controlled trial

Abstract

Adolescence is a pivotal period of physical, psychological, and cognitive development during which individuals are highly vulnerable to nutritional deficiency. Undernutrition, overweight/obesity, and anemia are prominent public health concerns in low- and middle-income countries, including Nepal. Anemia affects nearly one-quarter of individuals aged 10–24 years globally, with a disproportionately high burden in resource-constrained settings. This study primarily aims to evaluate the effectiveness of a theory-driven school-based nutrition education intervention in improving dietary behaviors, health literacy, and nutritional status among adolescent girls in rural Nepal. This two-arm randomized controlled trial (RCT) evaluated the effectiveness of the Nutrition Education Intervention for Promoting Health (NEIPH) program for improving the nutritional status of adolescent girls in rural Nepal. Adolescent girls (200) with low serum ferritin levels (40.7–75.7 ng/mL), enrolled in grades 7–9 across 19 public schools in Annapurna Rural Municipality, were randomly assigned to either an intervention (103 girls from nine schools) or a control (97 girls from 10 schools) group. The intervention group received two 60-min interactive education sessions over 1 month, school-based monitoring, and a standardized educational booklet. The sessions incorporated multimedia presentations, role-play activities, group discussions, and teach-back exercises to reinforce key concepts. The control group received booklets approved by the National Health Education, Information, and Communication Center. The educational content covered balanced nutrition, dietary sources, anemia prevention, adolescent health, and menstrual hygiene and was delivered using multimedia tools and participatory techniques. The NEIPH intervention is expected to be a viable approach for improving the nutritional status and reducing anemia by influencing the behaviors of adolescent girls. The combined use of the theory of planned behavior and the teach-back method represents a novel and structured approach to enhance comprehension, promote self-efficacy, and foster sustained behavioral change. The trial is currently ongoing, and no outcome data have been analyzed. This paper provides a detailed account of the theoretical framework, intervention development, and implementation procedures to promote methodological transparency and reproducibility.

Introduction

Adolescence is a phase of human development marked by rapid physical, psychological, and social changes. Optimal nutrition during this phase is essential for growth, cognitive function, and the prevention of chronic diseases [1, 2]. However, in low- and middle-income countries (LMICs), adolescent malnutrition, including underweight, overweight, and anemia, remains a major public health concern [3–5]. Cultural factors, dietary norms, peer pressure, and limited food access could shape adolescent eating behaviors and nutritional outcomes [6]. A multinational report documented anemia prevalence in reproductive-age women as 41.8%, 58.5%, and 40.6% in Bangladesh, the Maldives, and Nepal, respectively [7]. In South Asia, nearly 50% of adolescent girls have anemia, 10% experience stunted growth, and 3% are underweight, highlighting the urgent need for intervention [8, 9]. In Nepal, nearly 30% of females aged 15–19 years have a body mass index (BMI) below 18.5, and 13% of women of reproductive age are underweight [10]. Early marriage and adolescent pregnancy exacerbate this issue, as 16.7% of women aged 15–19 years experienced pregnancy or childbirth [11]. These issues have long-term implications for maternal and fetal health outcomes [12, 13], prompting the government to adopt the “National Adolescent Development and Health Strategy 2075” in 2019 to ensure that every Nepalese adolescent can lead a healthy and productive life by 2025 [14].

Adolescent nutrition is increasingly recognized as the foundation for preconception care [15]. It has been recognized that integrating preconception care into the health continuum could ensure long-term well-being from adolescence to adulthood [16]. This approach optimizes maternal health before conception. This is particularly relevant in Nepal, where adolescent pregnancy rates remain high. Malnutrition before conception can result in low birth weight, neonatal mortality, and intergenerational health risks [17, 18]. However, adolescent girls in Nepal often face significant barriers to making informed health decisions because of sociocultural norms, gender inequality, and limited health education [19]. Low health literacy and autonomy contribute to poor dietary behaviors and worsen maternal and child health disparities [20]. Empowering adolescent girls with nutritional knowledge and self-care skills is essential for informed choices and pregnancy preparedness [21].

The lack of behavior-focused interventions for adolescent girls is a major barrier to effective preconception care in LMICs [22]. Although iron and folic acid (IFA) supplementation programs are common interventions, they rarely address the behavioral determinants of poor nutrition or promote long-term dietary improvements. A shift from knowledge-based interventions to interventions promoting behavioral change and self-efficacy is needed to equip adolescent girls with the skills to make independent health decisions and adopt sustainable self-care practices [23].

Despite Nepal’s IFA supplementation programs, adolescent anemia prevalence remains above 40%, suggesting that supplementation alone is insufficient and behavioral change interventions are needed [24, 25]. Most school-based nutrition education programs in Nepal emphasize knowledge dissemination without integrating structured theoretical frameworks for behavior change; however, it has been recognized that supplementation alone is insufficient, and a more comprehensive approach that includes behavior-change interventions is crucial [26]. This represents a critical gap in the literature. While existing programs increase knowledge, they often fail to drive meaningful behavior change due to a lack of robust theoretical underpinnings and interactive learning strategies. This study combined the theory of planned behavior (TPB) with the teach-back method, two complementary approaches targeting behavior change and health literacy, to address this gap. The TPB posits that human behavior is influenced by attitude, subjective norms, and perceived behavioral control [27] and has been widely applied to improve dietary habits and health behaviors [28, 29]. The TPB could provide a structured framework for understanding and influencing adolescent girls’ attitudes, perceived norms, and behavioral control regarding nutrition. In contrast, the teach-back method strengthens message comprehension and retention through interactive learning. TPB-based interventions have effectively promoted positive health behaviors, including nutrition-related changes, in diverse populations [30, 31]. By incorporating the TPB, this study aims to empower adolescent girls to make independent dietary choices and improve their nutritional status. This study also incorporates the teach-back method, an educational strategy that enhances health literacy and behavioral adoption. This method requires participants to re-explain the learned information in their own words, thereby reinforcing comprehension and ensuring knowledge retention [32, 33]. It can improve nutrition-related self-efficacy and long-term adherence to healthy behaviors [34]. Unlike passive didactic education, the teach-back method actively engages participants, encouraging critical thinking and self-management skills. Facilitators will use a checklist-based assessment to evaluate participants’ ability to re-express key nutrition messages during sessions. Combining TPB and teach-back in this study aims to strengthen adolescent girls’ ability to make informed dietary decisions and promote self-care practices for preconception health.

Addressing adolescent malnutrition requires more than supplementation; holistic approaches incorporating nutritional education and behavioral change strategies are essential. Evidence from South Asia suggests that nutrition-focused interventions improve dietary habits, reduce the prevalence of anemia, and enhance adolescent health. Community-based interventions in India have improved hemoglobin levels, anemia awareness, and dietary practices in adolescent girls [35]. Similarly, another study reported increased hemoglobin levels and BMI and improved knowledge, attitudes, and practices following dietary counseling and supplementation [36]. Interventions grounded in behavioral theories have also shown the potential for promoting healthy dietary practices; however, improvements in attitudes and self-efficacy are limited [37]. Despite these promising results, the findings remain underexplored in Nepal, where sociocultural and resource constraints create unique challenges.

Although malnutrition in adolescents is a growing concern in Nepal, the effectiveness of educational and awareness interventions remains poorly understood. Building on previous research, the NEIPH adopted a comprehensive, context-specific approach integrating culturally relevant nutrition education, evidence-based behavior-change strategies, and participatory methods to enhance acceptability and effectiveness. The designed intervention package was approved by the National Health Education, Information, and Communication Center (NHEICC) [38]. Using an RCT design, this study aims to evaluate the impact of the intervention on key nutritional outcomes, including anemia, underweight, and overweight/obesity. By leveraging schools as primary delivery platforms, the NEIPH trial aims to bridge research gaps and inform scalable nutritional education programs. By incorporating TPB and the teach-back method, this study advances preconception care and adolescent nutrition, fostering long-term health improvements and breaking the cycle of intergenerational malnutrition. Although the trial has begun, no outcome data have been analyzed to date. This paper focuses on the rationale, design, and implementation details of the intervention to promote transparency and inform future public health efforts.

Objective and hypothesis

This study aims to evaluate the effectiveness of a TPB-based nutrition education intervention for improving health literacy and self-care skills among adolescent girls, ultimately leading to reductions in underweight, overweight/obesity, and anemia.

The hypothesis of this study is as follows: The hypothesis is grounded in the theoretical frameworks of the theory of planned behavior and the teach-back method, which are designed to achieve measurable, incremental changes in behavioral intention, perceived control, and comprehension. The intervention is hypothesized to produce significant improvements in nutritional knowledge and health literacy, and modest, measurable improvements in dietary intentions and selected nutrition-related practices, rather than large-scale behavioral change. These expectations are consistent with previous evidence showing that brief TPB-based and teach-back interventions can enhance intention formation, self-efficacy, comprehension, and small but meaningful behavioral adjustments [28, 29]..

Methods

Design

This study follows a two-phase design, comprising an initial observational baseline study followed by an interventional study using a randomized controlled trial (RCT) design. The baseline study aims to assess the current nutritional status of adolescent girls, whereas the intervention study is designed to evaluate the effectiveness of a school-based nutrition education intervention. The RCT follows a parallel-group design, in which participating schools are randomly assigned to either the intervention or control group.

Setting and population

This study is being conducted in the Annapurna Rural Municipality of Kaski District, Nepal. Annapurna Rural Municipality is a geographically diverse mountainous region that faces significant nutritional challenges. All public schools within the rural municipality were included in the baseline observational study and RCT. For the RCT, all public schools were randomly assigned to the intervention or control groups. Adolescent girls enrolled in grades 7–10 of public schools within the Annapurna Rural Municipality were eligible to participate in this study. However, participants will be excluded if they fail to provide consent or if their parents or guardians do not provide informed consent. Additionally, adolescent girls currently undergoing treatment for severe medical conditions, chronic illnesses, or health conditions that could potentially confound the study outcomes will not be included.

Sample size calculation

The sample sizes for both the baseline observational and interventional studies (RCT) were determined separately to align with their respective objectives. For the baseline study, the required sample size was determined using OpenEpi software [39]. based on a previously reported 31% prevalence of anemia among school-going adolescent girls in Nepal [3]. Using this prevalence estimate with a 5% margin of error, 95% confidence level, and a design effect of 2 to account for potential clustering effects within schools, the minimum sample size required was 540 adolescent girls. However, in practice, all adolescent girls enrolled in public schools within Annapurna Rural Municipality will be included to ensure comprehensive baseline data collection.

For interventional studies, the sample size was estimated using a formula to compare the proportions between the two groups.

$$n={[\frac{Z\alpha \sqrt{(1+({\displaystyle \frac{1}{m}})p*(1-p*)}+Z\beta \sqrt{({\displaystyle \frac{p1(1-p1)+p2(1-p2)}{m}})}}{p1-p2}]}^2$$

The calculation considered a significance level (α) of 0.05 (two-tailed), a power (1−β) of 80%, and an assumed prevalence of anemia in the control group (p₁) of 30%. A 22% reduction in prevalence was anticipated in the intervention group (p₂), based on findings from a similar nutrition education and counseling intervention conducted in Ghana [40]. Using these parameters, the initial calculation yielded a required sample size of 54 participants per arm (control and intervention). However, acknowledging potential participant attrition, noncompliance, and logistical challenges, the sample size was increased to enhance statistical robustness. As a result, the final sample size was set at 103 participants in the intervention group and 97 in the control group, maintaining a nearly 1:1 allocation ratio.

Study procedures

Recruitment and consent

A list of public schools inside the municipality was created, and eligible schools were identified in collaboration with the education section of the Annapurna Rural Municipality. Formal permission was obtained from the school administrations before proceeding with participant enrollment. During the baseline screening phase, 476 adolescent girls were assessed for eligibility through biomarker testing, i.e., complete blood count (CBC) and iron profile, including hemoglobin levels (with altitude correction) [41], serum ferritin, serum iron, TIBC, and transferrin saturation. Among them, 322 had low serum ferritin levels. Grade 10 students were excluded from the intervention phase because of their limited availability for follow-up. Consequently, 200 adolescent girls in grades 7–9 with low ferritin levels were eligible for the intervention study. Serum ferritin, and not hemoglobin, was used as the primary biomarker to determine eligibility for the intervention. This decision was made to improve diagnostic accuracy and better reflect iron-deficiency status. Serum ferritin testing, as part of an iron profile, provides a noninvasive and comprehensive approach for assessing nutritional iron status. Using hemoglobin alone risks missing cases of latent or “hidden” anemia, in which hemoglobin levels remain within normal ranges despite depleted iron stores. In contrast, ferritin more reliably reflects body iron reserves and allows the earlier detection of iron deficiency before it manifests as anemia. Written consent forms were sent to the parents or guardians of eligible adolescents to ensure informed participation. Only participants whose parents or guardians provide written informed consent will be enrolled. In addition, the adolescent girls themselves will provide written assent before participating. The informed consent and assent processes will be conducted both at baseline and during the final data collection phase, ensuring that the participants and their guardians remain fully aware of the study objectives and procedures.

Cluster sampling was used at the school level to minimize the risk of contamination and information sharing between groups. In this approach, each school served as a cluster, and all eligible adolescent girls (with low ferritin levels) in the selected schools were included in the same study group. Cluster randomization was conducted in both the intervention and control groups at the assigned school. The research team initially listed the number of eligible participants at each school. Each school was assigned a unique identifier to maintain blinding and to reduce selection bias.

Schools were randomly allocated using a computer-generated random sequence created using Microsoft Excel’s RAND() function. The randomization process was monitored until approximately 100 eligible girls were included in one group to ensure an approximate balance in participant numbers across groups. Allocation concealment was ensured by placing each school’s identifier in sealed opaque envelopes, which were then drawn individually to determine the group assignments. Schools were assigned to the intervention group until a target number of approximately 100 eligible participants was reached (103 participants were obtained from 9 schools). The remaining 10 schools were assigned to the control group, comprising 97 eligible participants.

Intervention

All participants, regardless of their assigned group, received educational material in the form of a booklet developed by the research team and approved by the NHEICC, Nepal. The NHEICC serves as the primary regulatory body for health education and awareness materials in the country, ensuring that the content aligns with national health guidelines [38]. The key difference between the intervention and control groups was the delivery of the additional interactive educational sessions. Participants in the control group received only the booklet containing comprehensive information on nutrition, anemia, and menstrual health. In contrast, participants in the intervention group received both the booklet and two interactive nutrition education sessions, each lasting 60 min, conducted over 1 month at 2-week intervals. Facilitators were comprised of public health or nursing graduates who possessed previous experience in adolescent health or community nutrition programs. Before implementation, all facilitators completed a structured 2-day training workshop. This workshop covered the core theory of planned behavior concepts, techniques for participatory facilitation, the effective use of audio-visual aids, and the standardized application of the teach-back method checklist. Competency was formally assessed through supervised practice sessions and role-play exercises to ensure consistent delivery across all intervention schools.

Each session incorporated participatory techniques, including multimedia presentations (e.g., PowerPoint and videos), role-play activities, group discussions, and the teach-back method, where participants were asked to re-express key information in their own words. This approach ensured comprehension and reinforced health literacy through active engagement. The interactive education sessions focused on the following core topics:

• Introduction to nutrition: Overview of the importance of nutrition for adolescents, focusing on healthy eating behaviors and the role of balanced nutrition in overall well-being

• Healthy eating habits: Information on major food groups, their nutritional benefits, and the importance of a nutritious breakfast

• Junk food awareness: Exploring why junk food is popular, its negative health effects, and how to make healthier food choices

• Anemia in adolescents: Detailed information about anemia, including causes, symptoms, and foods, can help reduce the incidence of anemia, particularly iron-rich foods.

• Menstrual health: Guidance on maintaining a healthy diet during menstruation, managing menstrual bleeding, and common misconceptions regarding menstrual health.

The intervention was designed to strengthen nutritional knowledge, enhance comprehension through teach-back activities, and modestly support early shifts in dietary intentions and simple daily practices. Rather than aiming for large or immediate behavioral change, the two-session program focuses on achieving measurable but incremental improvements in intention formation, perceived behavioral control, and the adoption of small, feasible nutrition-related actions. Facilitators used a checklist-based approach to assess the participants’ ability to re-express their educational content, allowing for real-time feedback and clarification. To ensure sustained exposure to the core concepts, these sessions are reinforced by school-based strategies, including the orientation of teachers to support and promote key messages during regular class hours. Regular assessments were conducted throughout the study period to evaluate the effectiveness of the intervention and its impact on participants’ knowledge, attitudes, and health outcomes. The detailed study process is illustrated in Fig. 1.

Fig. 1.

Flow diagram of the study

Data collection

Data will be collected in both phases to assess the current nutritional status of adolescent girls and evaluate the impact of the intervention. Data will be collected during the baseline phase to establish the initial health and nutritional status of the participants before the intervention. This information will serve as a reference for evaluating post-intervention changes. The data collection process will begin with structured interviews to gather demographic information, dietary habits, nutritional knowledge, and menstrual health awareness. Trained enumerators will conduct face-to-face interviews using a validated questionnaire, ensuring data confidentiality and minimizing response bias by conducting surveys in a private setting within the school premises. Data will be entered in real time using electronic tablets equipped with the Kobo Toolbox, which allows for immediate validation and minimizes the likelihood of errors. Field supervisors will conduct daily data reviews and cross-check responses for inconsistencies. In cases where discrepancies arise, the participants may be contacted for verification.

Instruments

This study uses standardized and validated tools to assess outcomes. Health literacy is measured using the 14-item Health Literacy Scale (HLS-14) developed by Suka et al. (2013) [42] and rated on a 5-point Likert scale, which has demonstrated good internal consistency (Cronbach’s alpha = 0.81) [42]. Menstruation-related attitudes were evaluated using the Adolescent Menstrual Attitude Questionnaire (AMAQ) [43], comprising 58 items rated on a 5-point Likert scale with a test reliability of 0.91. A rigorous translation process was followed to ensure that the tools were appropriate for the Nepalese context. Two independent bilingual translators conducted a forward translation of the original instruments into Nepali. A single reconciled version was produced by synthesizing the two translations. Following this, two additional bilingual individuals, blinded to the original instruments, carried out back-translation into English. An expert panel composed of a nutritionist, psychologist, public health expert, and language specialist reviewed all versions to ensure conceptual, semantic, and content equivalence. The reconciled version was subsequently pilot-tested with 33 adolescent girls from a non-study school through cognitive interviews to assess clarity, relevance, and acceptability. Minor wording revisions were made based on this feedback.

Anthropometric measurements will be conducted to assess participants’ nutritional status. Height and weight will be measured using calibrated electronic weighing scales and portable stadiometers. Body weight will be recorded to the nearest 0.1 kg and height to the nearest 0.1 cm. All enumerators will follow standardized measurement techniques, with duplicate readings taken and averaged to ensure accuracy. If discrepancies arise, a third measurement will be taken for verification. Biochemical assessments will be performed to evaluate iron status and the prevalence of anemia. Training laboratory technicians will collect venous blood samples (5 mL) under sterile conditions. These samples will be transported under controlled conditions to the Clinical Analysis Laboratory at Fistel Hospital Pvt. Ltd., Pokhara, Nepal, where they will be analyzed using standardized laboratory protocols. CBC will be assessed using the BeneSphera 3-part hematology analyzer, serum ferritin levels will be measured using a fully automated chemiluminescence immunoassay analyzer, and serum iron levels will be evaluated using the IRON Kit. All enumerators and supervisors will undergo extensive training in survey administration, anthropometric measurements, and electronic data collection methods to ensure the reliability of the data collection.

Following the completion of baseline assessments, the intervention phase will be implemented to evaluate the effectiveness of a school-based nutrition education intervention for improving adolescent nutritional health. Data collection during this phase will focus on measuring post-intervention changes in nutritional knowledge, dietary habits, menstrual health awareness, and nutritional biomarkers. The participants will be reinterviewed using the same structured questionnaire administered during the baseline phase. This will enable a direct comparison of pre- and post-intervention responses, providing insights into the intervention’s impact on knowledge and behavior. Anthropometric measurements will be repeated using the same standardized procedures as in the baseline phase, enabling the assessment of changes in BMI and the prevalence of underweight, overweight, and obesity. Venous blood samples will again be collected to reassess hematological and biochemical markers, including hemoglobin, ferritin, and serum iron levels, following the same laboratory protocols as in the baseline phase. This will ensure the consistency and comparability of the biochemical outcomes. Multiple quality assurance measures will be implemented to maintain data integrity throughout the intervention phase. Enumerators will receive periodic refresher training, and field supervisors will conduct random spot checks to verify data accuracy. Data entry will continue to be managed electronically through the Kobo Toolbox, with built-in validation checks to prevent errors. Any inconsistencies in the anthropometric or biochemical measurements will be addressed through verification procedures, including repeat assessments where necessary.

Outcome assessment

The primary outcomes focus on biochemical and anthropometric measures that reflect changes in nutritional status. The success of the intervention will be evaluated through changes in BMI to assess reductions in underweight, overweight, and obese individuals. Improvements in hemoglobin, serum ferritin, and serum iron levels will indicate enhanced iron intake and absorption, with a decline in anemia prevalence serving as a key marker of efficacy. Secondary outcomes assess behavioral and knowledge-based changes. The intervention is expected to improve nutritional knowledge, dietary diversity, and iron-rich food consumption while reducing reliance on processed and junk foods. Awareness of menstrual health and its link to nutrition is also expected to increase, promoting better dietary choices during menstruation. Additionally, health literacy improvements, measured using the 14-item Health Literacy Scale (HLS-14), will reflect participants’ enhanced ability to interpret and apply health-related information, leading to better self-care and informed decision-making.

Data management and analysis

All data will be collected using the Kobo Toolbox and exported for cleaning and analysis using SPSS version 26. Before analysis, the dataset will be checked for completeness, missing values, outliers, and normality of continuous variables. Data-cleaning procedures will include identifying and correcting inconsistencies, with multiple imputations considered for missing data exceeding 10%, assuming that the data are missing at random (MAR). Descriptive statistics will be used to summarize the baseline characteristics of participants in both the intervention and control groups. Continuous variables, such as age, hemoglobin levels, and BMI, will be presented as means and standard deviations if normally distributed or as medians and interquartile ranges if not normally distributed. Categorical variables such as grade level, dietary practices, and anemia status will be reported as frequencies and percentages. Independent t-tests will be used for continuous variables following a normal distribution to compare baseline characteristics between the intervention and control groups, whereas Mann–Whitney U-tests will be used for non-normally distributed continuous variables. When the expected cell counts are small, categorical variables will be compared using the chi-square or Fisher’s exact tests. These comparisons will assess the equivalence of the groups before the intervention implementation.

The primary outcomes include changes in hemoglobin levels, serum ferritin levels, and BMI. Within-group analyses comparing pre- and post-intervention outcomes will be performed using paired t-tests for normally distributed data or Wilcoxon signed-rank tests for non-normally distributed data. Effect sizes will be reported with 95% confidence intervals, and Cohen’s d will be calculated for continuous variables to estimate the magnitude of the intervention effects. Secondary outcomes include changes in knowledge, attitudes, and practices (KAP) related to nutrition and health, health literacy scores (HLS-14), menstrual distress scores (MDQ), and food intake patterns. Comparisons of secondary outcomes between groups will be performed using independent t-tests for continuous outcomes or Mann–Whitney U-tests when the data are non-normally distributed. Categorical secondary outcomes will be compared using the chi-squared test or Fisher’s exact test, as appropriate. Multivariate regression analyses, using linear regression for continuous outcomes and logistic regression for categorical outcomes, will be conducted to adjust for potential confounding variables and explore the predictors of positive health outcomes. Multivariable regression analyses will adjust for baseline imbalances and known confounders, such as parental education, household food security, and prior exposure to nutrition programs. All statistical tests will be two-tailed, and statistical significance will be set at p < 0.05.

Monitoring and quality assurance

Regular monitoring will be conducted throughout the study to ensure data quality and regulatory compliance. The Nepalese research team will oversee all phases of the study, including field operations and intervention implementation. They will be directly involved in the intervention phase to ensure adherence to the study protocols. Trained field personnel will be responsible for both biological sampling and survey data collection. Laboratory technicians collecting blood samples will receive practical training and demonstrations from the central Nepalese research team under the supervision of a medical doctor at a partnering hospital. This will ensure the accurate collection, safe handling, and proper storage of samples according to biomedical standards. The enumerators involved in survey data collection will undergo thorough orientation and training to maintain consistency and accuracy. Teachers will be oriented in advance to support the reinforcement of key messages during regular class hours, and parents will be informed of the program’s objectives to ensure home-level support. In terms of coordination, day-to-day operational management is carried out by the Nepal-based field coordination team, who oversee school engagement, participant follow-up, logistical planning, and implementation activities. This team meets weekly to review field progress and address emerging operational issues. The Japan-based academic team provides complementary remote oversight, methodological guidance, and periodic data quality checks, meeting monthly with the Nepal team to review progress and ensure consistent adherence to study procedures. Because the intervention is minimal risk and educational in nature, no formal Trial Steering Committee or Data Monitoring Committee was constituted; instead, oversight is maintained through these structured coordination mechanisms. No interim analyses or formal stopping rules were planned, as the study does not involve clinical or biomedical procedures that would warrant early termination criteria.

A Nepali research team and trained facilitators will conduct the process evaluation. This will include fidelity checks to monitor adherence to the intervention protocol, using structured observation checklists completed by independent supervisors during each education session. These checklists will document session duration, content coverage, facilitator adherence to materials, use of participatory methods (e.g., teach-back and role-play), and participant engagement. Facilitators will also complete standardized feedback forms after each session, detailing any deviations from the protocol, challenges encountered, and recommendations for improvement. Weekly debriefings will be held between facilitators and supervisors to review fidelity data, address inconsistencies, and provide additional coaching as needed. Participant satisfaction surveys will be conducted at the mid-intervention and endline stages to assess the perceived usefulness and acceptability of the intervention. These measures will help monitor the consistency, acceptability, and quality of intervention delivery. The Japan-based research team will be responsible for data cleaning, analysis, and ongoing remote monitoring to ensure quality assurance throughout this study.

Patient and public involvement

Local stakeholders were engaged to ensure contextual relevance and acceptability of the intervention. School administrators, teachers, and community representatives provided input during the development and piloting of the intervention materials. Adolescents participated in the pilot testing of the educational content and questionnaires, contributing feedback on clarity and cultural appropriateness. The final intervention package was further refined and endorsed through expert consultations facilitated by the National Health Education, Information, and Communication Center (NHEICC). However, adolescents, parents, or community members were not involved as formal patient or public contributors in the governance of the study, nor in decisions related to trial design, conduct, or dissemination plans.

Timeline

Concept development and funding applications were initiated in October 2022. Ethical approval and trial registration took place from January 2024 to April 2024. Baseline assessments were conducted from May 2024 to June 2024. Intervention development and delivery spanned June 2024 to May 2025, with follow-up occurring simultaneously. The endline assessment and analysis are scheduled from May 2025 to September 2026 (Fig. 2).

Fig. 2.

Timeline of the trial

Ethical consideration

This study was approved by the Ethical Review Board of the Nepal Health Research Council, Kathmandu, Nepal (proposal ID 704–2023, approved review date: January 23, 2024). The trial has been registered with the Japan Registry of Clinical Trials: https://jrct.niph.go.jp/en-latest-detail/jRCT1052240007 on April 05, 2024. Formal permission to conduct the study was obtained from the Education Section of Annapurna Rural Municipality and the administration of the participating schools. Before enrollment, written informed consent will be obtained from the parents or legal guardians of all participants. Additionally, adolescent participants will provide written assent using a structured assent form, ensuring voluntary participation and adherence to ethical research standards. The enumerators were trained in ethical conduct to maintain a nonjudgmental and supportive environment, particularly for sensitive topics such as menstrual health, to promote psychological safety and address potential stigma. All data will be collected in private spaces to ensure the participants’ comfort. The data will be stored in password-protected files accessible only to the research team. Unique identifier codes are used instead of the participants’ names to ensure confidentiality. Procedures for managing protocol amendments and deviations were established during the initial design phase of the trial. These included submitting any proposed modifications to the Ethical Review Board of the NHRC for approval, notifying the sponsor and funder, and disseminating approved updates through the principal investigator to all study centers and field teams, with revised versions maintained in the Investigator Site File. Any protocol deviations, if they occurred, were to be documented using a formal deviation or breach report, and all approved amendments would be updated in the Japan Registry of Clinical Trials. However, during the period covered in this methodological paper, no deviations or changes warranting protocol amendments were identified.

Trial status

Recruitment for this trial began in October 2022 and ended in March 2024. Initial data gathering encompassing baseline measurements such as BMI, hemoglobin, and iron profiles was completed. The intervention phase is ongoing and is expected to be completed by September 2025. Periodic follow-up evaluations were performed to track the progress and ensure data accuracy. No outcome data has been analyzed yet.

Discussion

This study is one of the few randomized controlled trials to assess the effectiveness of a school-based nutritional education intervention in reducing anemia and improving the nutritional status of adolescent girls in rural Nepal. Previous studies in South Asia have demonstrated the efficacy of nutrition education in enhancing dietary practices and awareness among adolescents [44]. A 6-month health education intervention in India significantly improved hemoglobin levels and reduced the prevalence of anemia among adolescent girls [45]. Similarly, a quasi-experimental study conducted in Banepa found that the health education intervention effectively increased nutritional knowledge and attitudes among school-going adolescents [46]. A cluster-randomized controlled trial in Dolakha and Ramechhap districts in 2020 found that integrating school garden programs with nutrition education and WASH interventions significantly improved fruit and vegetable consumption and hygiene behaviors while reducing intestinal parasitic infections [47]. However, its effect on stunting and anemia has been inconsistent, underscoring the complexity of holistically addressing malnutrition. These mixed results highlight the need for tailored interventions that consider local contexts and behavioral determinants.

This study is among the few in Nepal that use the TPB to improve adolescent nutrition. Unlike conventional programs, it emphasizes behavioral changes through a structured theoretical framework. Additionally, incorporating the teach-back method promotes health literacy, self-efficacy, and long-term behavioral change, setting this study apart from previous interventions. The teach-back method is a communication technique where participants are asked to repeat the information shared with them in their own words, ensuring understanding and reinforcing learning. It is widely used to confirm comprehension and to improve knowledge retention, particularly in health education. It also contributes to preconception care by equipping adolescent girls with the self-care and decision-making skills essential for optimizing pregnancy outcomes. Given Nepal’s high adolescent pregnancy rates, improving prepregnancy nutrition is crucial for reducing maternal and neonatal complications [17, 18]. Research has shown that empowering adolescent girls with health knowledge and autonomy leads to better maternal health outcomes [22, 23]. By fostering independent decision-making, this study aimed to break the cycle of malnutrition and promote intergenerational health improvements. This study evaluates the effectiveness of a TPB-based, teach-back method-integrated nutrition education intervention among rural Nepalese adolescent girls. These findings will provide valuable insights for scaling up effective nutrition programs in resource-limited settings, ultimately promoting adolescent health, preconception preparedness, and long-term maternal well-being.

The NEIPH intervention aims to improve KAP regarding nutrition and anemia prevention in the intervention group compared with the control group. Because the intervention consists of only two structured sessions, the expected behavioral impact is intentionally limited to modest but meaningful improvements. Prior studies indicate that brief TPB-informed and teach-back-based interventions can lead to measurable gains in intention, self-efficacy, comprehension, and early changes in specific dietary practices, even within short time frames [32, 33, 37]. Therefore, this study aims not to achieve substantial behavioral transformation but to facilitate early, measurable shifts in dietary intentions and simple nutrition-related actions that have the potential to accumulate over time [28, 29]. Prior studies suggest that nutrition education can significantly enhance KAP regarding malnutrition [48]. This study seeks to foster sustained behavior change and improve health outcomes by utilizing educational materials, interactive sessions, multimedia tools, and participatory learning techniques. The TPB provides a framework for understanding how knowledge and attitudes translate into health-related behaviors, ensuring that the intervention not only imparts knowledge but also enhances self-efficacy and behavioral intentions. The integration of the teach-back method further reinforces learning by encouraging participants to articulate and retain key concepts.

Despite numerous nutritional initiatives in Nepal, there is a lack of comprehensive evidence regarding their long-term effectiveness, particularly among rural adolescents. In Nepal, poor diet, menarche, excessive menstrual bleeding, and acute infections such as parasitic infections make girls vulnerable and reduce iron levels in their bodies [49]. Additionally, many girls miss school because of menstrual cramps, experience mental distress [50, 51], and have restricted nutritious food intake during menstruation [52, 53]. Menstrual health issues are often associated with low hemoglobin levels and poor nutritional status [54].

Addressing menstruation-related factors is crucial in tackling adolescent malnutrition. This study examines the prevalence and predictors of underweight, overweight/obesity, and anemia among school-going adolescents while developing, implementing, and evaluating a health education intervention to mitigate these issues. Given Nepal’s high adolescent pregnancy rates, prevention of malnutrition during this period is essential. This study also explored socio-environmental factors, health behaviors, and other contributors to adolescent nutritional challenges, providing a holistic perspective. If proven effective, this model could be scaled up through integration into the National School Health Program in collaboration with the NHEICC and the Ministry of Education. Unlike previous studies focusing primarily on anemia reduction, this study took a broader approach, addressing multiple aspects of adolescent nutrition, including dietary intake, menstrual health, and behavior-change strategies. This pilot project aims to foster healthy adolescent transitions and promote preconception care.

The NEIPH trial includes follow-up assessments over 1 year to evaluate the sustainability of nutrition education programs in low-resource settings. If successful, the intervention can be scaled up and integrated into national school health initiatives, leading to long-term improvements in adolescent health. These findings will provide critical insights for policymakers, educators, and public health officials to address malnutrition and anemia in similar contexts. The intervention uses a multicomponent approach linking school-based nutrition education to broader environmental, family, and teacher-based strategies [55]. Notably, South Asia, West and Central Africa, and Eastern and Southern Africa reported the highest prevalence of underweight women and adolescent anemia, with three out of five adolescent girls and women worldwide suffering from anemia [56]. Addressing these issues through effective behavior-focused interventions is essential for improving adolescent and maternal health outcomes. The findings of this study will be shared with Annapurna Rural Municipality, provincial and national stakeholders, and will be published in a peer-reviewed journal.

Conclusion

NEIPH is an innovative initiative that uses a health education intervention package based on the TPB to promote the nutritional status and healthy behaviors of adolescent girls living in rural areas. It may be useful in preventing overweight/obesity, underweight, and anemia, ultimately contributing to safer motherhood from the viewpoint of preconception care. It further offers insight into how nutritional education can help shape the future behaviors of adolescent girls. Few studies have examined the relationship between menstruation and nutritional status among Nepalese adolescents, a gap this study aims to address by including menstrual health education as a core component. These new perspectives will supplement the current understanding and aid in directing treatments aimed at at-risk populations. If demonstrated to be effective, the intervention, whose content has been approved by the NHEICC, offers strong prospects for scalability through a teacher-led model and integration into national platforms like the National School Health and Nutrition Programme, facilitating adoption by local governments and rural municipalities.

Trial registration

Japan Registry of Clinical Trials https://jrct.niph.go.jp/en-latest-detail/jRCT1052240007. Registered on April 05, 2024.

Abbreviations

ARM

Annapurna Rural Municipality

DEFF

Design effect

FPC

Finite population correction factor

NEIPH

Nutrition education intervention for promoting health status

RCT

Randomized controlled trial

TPB

Theory of planned behavior

HLS

Health Literacy Scale

MDQ

Menstrual Distress Questionnaire

KAP

Knowledge, attitude, and practices

CBC

Complete blood count

Authors’ contributions

TRB, conceptualization of the study, design of the research, coordination and supervision of the research project, methodology, finalization of health education materials, and writing—review and revision. SP, conceptualization and framing of the method paper, project administration, and methodology and literature search and review, finalization of health education materials, writing—original draft, and writing—review and revision. NC, project administration, field investigations, coordinated training programs, and writing—review and revision. YOT, translation and international collaboration and writing—review and revision. AN designed the research, coordinated and supervised the laboratory work, and writing—review and revision. RK, development of health education materials and writing—review and revision. AI, contributed to the theoretical framework of the study, particularly in examining the application of the theory of planned behavior, and writing—review and revision. KL, structuring and organizing the overall study design and writing—review and revision. HS, principal investigator, secured research funding, conceptualized and designed the study, developed the research protocol, provided methodological leadership, supervised overall study planning, offered academic guidance, and critically reviewed and approved the final manuscript.

Funding

This study was supported by the Japan Society for the Promotion of Science (JSPS) under Grant Number 22KK0026 (Principal Investigator: Hiroko Sakai).

Data availability

No data are associated with this article.

Ethics approval and consent to participate

The research protocol was reviewed and approved by the Nepal Health Research Council (Proposal ID 704–2023, approved review date: January 23, 2024).

Consent for publication

NA

Competing interests

The authors declare that they have no competing interests.