Digitalization of Juvenile Obesity Therapy: Intervention Protocol of KLAKSonline

Objectives: To adress the care gap for adolescents affected by overweight and obesity, particularly in underserved regions, digital therapy accessible regardless of time and location offers potential solutions, but currently lacks evidence on program parameters and effectiveness.
Methods: A planning model (Intervention Mapping Approach) served as theoretical framework. Given its lack of specificity in media implementation, it was extended using didactic models. The final concept approach included five steps encompassing 14 questions for designing digital therapy.
Results: The content of KLAKSonline is based on the health insurance-recognized program from the therapy center KLAKS Leipzig. It targets 12-17-year-olds with overweight and obesity and their parents in underserved regions. After an introduction week and distribution of participation packages, 30-week multidisciplinary therapy begins. The 158 units consist of 89 synchronous weekly video conferences and 69 asynchronous practical tasks. Associated digital resources (20 explainer videos, 22 expert videos, 121 digital worksheets) are utilized via a learning platform.
Conclusions: KLAKSonline differs fundamentally from analog therapy due to requirements, structure, learning and teaching pathways. A key feature is the reduced number of synchronous sessions. This is offset by asynchronous tasks that promote reflective engagement. To unlock the potential of digital obesity therapy and close the care gap, it is crucial to address feasibility, therapy actors’ satisfaction, effectiveness through randomized controlled trials, and required competencies for therapy professionals.

Key Words: Adolescents, Overweight, Digital Media, Sports Therapy

Obesity is an international public health issue, with steadily increasing number of affected patients (17, 30). The prevalence of overweight and obesity rises with advancing age, highlighting the need of targeting adolescents (29). Affected patients experience burdens due to subsequent health conditions (e.g., hypertension) (36). Resulting significant treatment costs also strain the healthcare system. Despite the need for early therapeutic measures, current approaches are relatively ineffective (42), particularly in underserved regions where treatment options are scarce (8). This lack leads to issues because of increased resource expenditure (travel time, costs for patients). Additionally, therapy participation is dependent on familiar factors due to the lack of independence and mobility in youth (40). Consequently, socioeconomically disadvantaged participants and their families (single parents, parents with multiple children) have a lower ability to access or sustain therapy (23).
Against this backdrop, digital transformation emerges as an opportunity (33), enabling self-regulated learning and seamless knowledge transfer into daily life (9). The COVID-19 pandemic acted as a catalyst for advancing digital intervention approaches in healthcare (35). However, evidence regarding the use of digital media in guideline-compliant therapy is limited, but necessary for the required provision of alternative tools for weight loss management (12).
For the systematic development of complex health and obesity interventions, proven models like the Intervention Mapping Approach (IMA) by Bartholomew (3) provide a methodological framework. Since intervention planning primarily addresses overarching themes, the didactic transmission in healthcare and planning models is scarcely considered. To properly attend to this transmission, didactic frameworks are emphasized. An established approach in this regard is the didactic hexagon according to Wernke und Zierer (41). This framework not only deals with questions focused on the IMA, such as program objectives and - design, but also goes beyond by encompassing more profound dimensions relevant to digital knowledge and practice transmission, including:
– Media usage: What hardware and software can be utilized?
– Spatial structures: What (digital) spaces are suitable for the therapeutic approach?
– Temporal structures: What timeframes and frequencies are suitable for digital therapy?
– Applied methods: What digital learning and teaching methods are therapy-appropriate?
In order to tackle program parameters for the development of digital obesity therapy for adolescents and their families in underserved regions, combining planning and didactic models is necessary. In this regard, current evidence is insufficient. Considering the care gap and digital transformation, this paper aims to outline theory-based parameters for the design of the digital therapy KLAKSonline.

Effective health and obesity intervention planning requires a structured approach based on models like Bartholomew’s IMA (3). The IMA includes six steps: needs assessment, program objectives, selection of intervention methods, program design, implementation planning and evaluation planning. However, digitalization of therapy demands examining didactic parameters beyond this model, served by established didactic models for media-supported education. For example, while the IMA focuses the overarching program planning for the therapy year, it does not address the impact of selected digital methods on the learning process. This requires didactic models, which address the planning of specific and effective therapy units, ensuring that digital methods are selected appropriately in accordance with the objectives of each unit. Due to its target group-orientation, the didactic hexagon according to Wernke and Zierer (41) allows for detailed exploration of program conception (26). Thus, digital health interventions require the combination of planning parameters and didactic aspects. To conceptualize KLAKSonline, the IMA serves due to its transparent methodology as a framework, whereas questions, derived from the didactic hexagon, complement the IMA steps in the digital transmission process. The synthesis of the models leads to program parameters and resulting questions for conceptualizing and implementing digital therapy, presented in table 1.

Step 1
The needs assessment covers questions from the IMA to depict the initial situation, analyzing causes, problems and needs of the target group. For KLAKSonline, this involves literature searches on obesity prevalence, causes, reduction measures, and the healthcare situation in underserved regions.

Step 2
Program objectives address questions from both the planning and didactic models. Objectives involve a comparison of the needs identified in step one. Targeted changes and outcome parameters are selected using existing therapy manuals and planning matrices.

Step 3
Conceptual strategies merges IMA’s third and fourth step, supplemented with didactic parameters according to Wernke und Zierer (41). For the resulting KLAKSonline program parameters, literature analyses were conducted using the databases PubMed and FIS education. Against the backdrop of existing national therapy guidelines, results were evaluated for their applicability to therapeutic use and strategies were derived accordingly.

Step 4
Implementation planning includes IMA parameters and develops concrete steps for the sustainable intervention. To structure the steps, milestones are set both in terms of content and timing, ensuring transparency in the implementation of digital therapy for therapy actors.

Step 5
Evaluation planning, also based on IMA parameters, includes the selection of an evaluation design, evaluation parameters, and the determination of suitable measurement instruments.

The 14 questions outlined in table 1 were addressed by the author team from March to December 2023 and are presented in the following.

The outpatient therapy center KLAKS Leipzig (Germany) has been providing care for adolescents with overweight and obesity and their families since 2007 as a non-profit organization. KLAKS follows the national “S3 Therapy and Prevention of Obesity in Childhood and Adolescence” guideline (39). The KLAKS therapy concept is standardized in accordance with the “Consensus Group for Obesity Education (KgAS)” program guide (19). Funding is provided by health insurances. Based on described program parameters, the KLAKS concept serves as foundation for conceptualizing the first theory-based outpatient digital therapy KLAKSonline in Germany.

Step 1
Internationally, 20% of children and adolescents face overweight, with 8% suffering from obesity (43). In Germany, the prevalence is slightly lower; however, the number of therapy centers underscores the lack of available care options even here (6). As of 2023, there are 29 certified obesity centers for approx. 780,000 affected children and adolescents (2). This shortage leaves affected individuals without treatment, exacerbating obesity conditions into adulthood. To counteract this problem, digitalization emerges as a solution, offering accessibility and practicality. Digital media has the potential to facilitate therapy participation regardless of location. In this context, the evident media presence and usage in everyday life offer the opportunity to facilitate the transfer of lifestyle changes into daily routines (33). However, concepts for digital obesity therapy are currently absent.

Step 2
In accordance with national guidelines, the following program objectives result for KLAKSonline: 1) Maintaining and improving physical performance, 2) Ensuring stable psychological, physical, and social development, and 3) Reducing standardized Body Mass Index (BMI-SDS).

Step 3
Conceptual strategies identify planning and didactic parameters that must be considered in the digitalization of therapy. Resulting challenges are tackled by literature analyses.

Program Actors
The program actors are participants and a team of multi-professional therapists. KLAKSonline targets adolescents aged 12 to 17 from the 16 German federal states. They receive specific training sessions for digital participation. Although guidelines recommend treating children aged 6 to 11, they are not included due to the factors age, place of residence, and digital competencies (39). The multidisciplinary staff includes nutritionists, psychologists, pediatricians, and sports therapists. Existing literature highlights that therapists in digital therapy require specific competencies, including hardware and software selection, digital communication skills, and providing learning support (27).

Framework Conditions
For participation, families require a reliable internet connection, as well as a smartphone, tablet or laptop. Additional materials are provided to families in a participation package, including a foam roller, resistance band, table tennis set, jump rope, and fitness tracker. The table tennis set serves as an example for demonstrating how to use the equipment. After explaining the use of the racket and ball in the physical activity unit, adolescents practice coordination exercises without a table. They also search nearby table tennis plates to play with family and friends. For the nutrition units, participants are provided with paper-based nutrition pyramids and printed recipe books. For instance, the nutrition pyramid is used to demonstrate the application of the materials, with therapists first explaining it in units on energy balance. During the therapy, participants practice categorizing everyday foods into the appropriate categories. To transfer knowledge into daily life, adolescents place the pyramid in their own living environment (kitchen), ensuring it serves as a benchmark for health-promoting food intake.

Time
After meeting participation requirements (see step 4), the therapy phase of 12-month commences. During the 30-week therapy period, the holidays of the 16 federal states in Germany are taken into account (20, 39). The digital program adopts an e-learning approach with 158 units (100%), combining synchronous face-to-face learning (89 units, 56.3%) and asynchronous learning (69 units, 43.7%). Face-to-face units are conducted via Zoom Video Communications, with two 60 min (minutes) units for adolescents and one for parents each week. Asynchronous learning is carried out on the learning platform without time constraints (16). The processing and uploading of asynchronous practical tasks require 30 min per unit.
Therapy Content
Therapy units are divided according to target group and therapeutic domain (19). Thus, 62 synchronous therapy units for adolescents are divided as followed: 30x physical activity, 15x psychosocial, 13x nutrition, 2x medical training and 2x organization. The 50 asynchronous practical tasks are based on synchronous therapy units to reinforce knowledge. However, parents units include 4x physical activity, 3x psychosocial, 13x nutrition, 3x medical training, 2x organization and 2x parent forums facilitating communication between guardians (19). The associated 19 asynchronous practical tasks are assigned, as illustrated in figure 1.

Digital Therapy Methods
The use of media necessitates a wide range of methods for therapy implementation, which include various functions. Digital methods utilized for the implementation of KLAKSonline are detailed below.

Learning Platform
The use of a learning platform contributes to being user-friendly and delivering knowledge in an engaging manner (1). The software Moodle 4.3 was chosen as platform for KLAKSonline. German adolescents use Moodle in school, thereby assuming familiarity. Moreover, the platform provides therapists a variety of methods and freedom in graphic design. Project stuff underwent training sessions to set up the platform, adapting its structure to be comprehensible. Moodle is used for organizing materials, submitting digital tasks, and offering communication.

Video Conference
Studies have demonstrated significant weight loss using telemedicine, including weekly video calls and counseling (38). KLAKSonline uses Zoom Video Communications for conducting 60 min synchronous video conference. This facilitates 89 therapy sessions for adolescents and parents to facilitate knowledge transfer, incorporating joint exercises and discussions. Therefore, Zoom features are utilized: breakout sessions provide participants with a secure space for small group work, a digital whiteboard enables collaborative brainstorming, and screen sharing allows for effective content sharing.

Explainer Video
Studies reveal, that the knowledge of adolescents is significantly improved after including explainer videos in online courses (21). Explainer videos use animation techniques to simplify complex content within a short period of time (1 to 3 min). Therapists creating KLAKSonline explainer videos use the Simpleshow software, producing scripts interpreted visually with AI-generated graphics. The used graphics are chosen to resonate with participants for better content transferability to daily life. Besides, therapists narrate the text, fostering a personal connection to the target group. The 20 explainer videos are presented in video conferences, allowing for interaction. The total video duration is 55 min, averaging 2.45 min (±0.29 min) each. Videos are integrated into practical asynchronous tasks and available on the learning platform.

Expert Video
Expert videos practically illustrate theoretically elaborated content and aim to enable participants to apply practical implementations at home. KLAKSonline therapists script, demonstrate workouts or prepare healthy recipes, film, and edit videos using iMovie. Because studies highlight the necessity of engaging in interaction to ensure understanding of practical skills, KLAKSonline integrates 22 expert videos into synchronous units to foster comprehension and dialogue (13). Each video has an average duration of 4.55 min (±1.06 min), totaling 104 min.

Digital Worksheet
To enhance student independence, problem-solving skills, and the transfer of acquired health behaviors into the home environment, there are digital worksheets available for almost each unit (5). Therapists develop the Word documents and release them weekly on the learning platform. Participants complete the tasks asynchronously at home. Results are uploaded.
The used digital therapy methods und functions presented here are complex and must be generated for each individual unit. This interplay is illustrated using a physical activity unit focused on healthy posture. At the weekly appointment, participants log into the learning platform and access a Zoom link for a video conference. After an interactive introduction, an explainer video on healthy posture is shown. Questions are addressed in a discussion, and understanding is checked with a digital quiz. To translate theory into practice, a therapist-led posture workout follows, explaining and ensuring functional exercise execution. This workout serves as the basis for the approximately 20 min expert video for home use. After the unit, participants log into the learning platform at self-chosen time to receive the practical task and digital worksheets for knowledge assessment and performance documentation. Participants complete the asynchronous task within one week and upload results to Moodle. Therapists review worksheets to prepare the follow-up therapy (table 2).Place
Instructors conduct therapy in a self-selected environment or on the premises of KLAKS, where hardware (e.g., cameras) is available. Physical activity units require participants to have sufficient space of 1 x 2 meters. Nutrition units necessitate the use of participants‘ own kitchens.

Step 4
The implementation phase of the 12-month digital therapy is divided into three phases, each characterized by distinct work processes by therapists (figure 2).

Preparation Phase
Recruitment occurs via website or through flyers distributed by health departments and pediatricians. After expressing interest by affected families, KLAKSonline staff holds a video conference to explain program details, test technical requirements (such as internet access and the availability of a functional device), assess basic digital literacy, and complete registration. Families receive the participation package. Participants must meet participation requirements: 1) medical diagnosis by pediatricians for anthropometric data, 2) psychological diagnosis by psychologists to set therapy goals, and 3) reflection with nutritionists on the previously maintained family’s nutrition protocol. Adolescents with contraindications are excluded. Finally, a technical introduction week is provided to ensure competent handling of hard- and software.

Therapy Phase
In each synchronous session, two therapists work in tandem: one leads the therapy as the thematic expert, while the other serves as backup to provide individual assistance in case of technical disruptions, ensuring participants can engage in the digital therapy. To adapt therapy goals for the target group during therapy and to assess knowledge retention, a reassessment of medical, physical, psychological, and nutritional parameters occurs after 6- and 12-months.

Aftercare Phase
Following therapy, a 2-year digital aftercare begins, with materials accessible via learning platform. Therapist appointments are arranged individually to discuss lifestyle changes or explore potential inpatient therapy options.

Step 5
To derive therapy adaptations and ensure sustainable improvement in therapy quality, it is necessary to evaluate corresponding process and outcome parameters such as:

Usability
The Design-Based Research (DBR) approach assesses usability through user satisfaction, measured via weekly team meetings and participant questionnaires, and analyzed using Mayring’s qualitative content analysis (25).

Adherence
Regular participation in KLAKSonline is monitored through attendance documentation by participating families during therapy units.

Satisfaction
Program stakeholders are surveyed using validated instruments, such as questionnaires on satisfaction with digital therapy (22), to ensure the program is appropriate for the target group.

Effectiveness
Baseline data are collected by multidisciplinary professionals, including anthropometric (e.g., BMI-SDS, blood glucose), psychological (assessment via questionnaire), nutritional (dietary diaries), physical performance (motor fitness tests) and activity data (step tracking) as recommended by the therapy guidelines (39). Follow-up assessments at 6- and 12-months track longitudinal development. Data from digital therapy can be compared with traditional therapy. For a control group design, participants of the in-person obesity therapy at KLAKS Leipzig will be examined (same age group, identical therapy content).

Efficiency
To assess the value of digital obesity therapy, the financial and personnel resources of KLAKSonline are calculated and compared with its effectiveness to determine its efficiency.

To address the care gap for adolescents with overweight and obesity in underserved regions, a digital therapy program was developed based on the certified German KLAKS concept. KLAKSonline comprises 112 therapy units for adolescents and 46 for parents over a 12-months period, implemented through synchronous and asynchronous methods. The therapeutic approach depicted differs significantly from analog programs, as will be demonstrated in light of the following discussion points.
The possibility of KLAKSonline participation is limited compared to traditional conservative therapy options. Literature indicates that learner need digital competence to independently participate digital therapy and to reflectively use technologies to counter risks like information overload (11, 37). Also, the transformation from analog to digital therapy requires participants to assume responsibility for their learning progress (24). However, children 8 to 11 lack necessary self-regulation to structure asynchronous tasks as well as digital competence for this transition (18). Therefore, they are excluded from
KLAKSonline, which ensures smooth therapy and reduces dropout risk due to technical and personal issues (14). A future therapy program for children aged 8 to 11 is possible, drawing on experiences from the outpatient therapy center KLAKS Leipzig (Parent-Child Program “KLAKS midis” (15)), KLAKSonline and existing digital obesity interventions for primary school children. A core element will be enhancing parental media literacy in joint parent-child units for knowledge transfer. Another challenge is the determination of indicators used to differentiate participants from underserved regions. Available resources (travel time, mobility, costs) must be equitably considered relative to the actual therapy needs. This ensures that only people lacking access to healthcare are addressed. Additionally, defining underserved regions serves a crucial role for therapy providers. Excluding participants with sufficient resources helps avoid competition between analog and digital therapy offers (4). In the future, suitability should be assessed based on family demands and resource availability.
The selection of technology for digital obesity and overweight programs is complex due to diverse options and a lack of unified criteria in literature (28). The technology selection of KLAKSonline considers availability, familiarity, and usability for the target group to promote program adherence (32). Besides, technologies were chosen to provide therapists with technical functions (e.g., digital organization and communication) and graphical design control. Other digital obesity reduction programs have opted for different technologies. The EVIDA study, for example, applied an app for daily weight tracking, leading to significant BMI reduction (10). This technology could enhance KLAKSonline’s effectiveness. Yet, utilizing additional apps might overwhelm participants, leading to potential dropouts. Given the increasing digitization in the healthcare system, it is essential to investigate media combinations, their methods and functions as well as their impact on the target group using a multifactorial design through a randomized controlled trial.
The described variety of media, digital methods and functions necessitates therapists to acquire specific competencies that differ from analog therapy (7). These include selecting, digitally creating, and instructing media during therapy preparation. Throughout therapy, effective didactic delivery is crucial, considering the transformation from traditional teaching to fostering independent learning (27). To prepare therapists for evolving competency demands, adequate education is essential, requiring theoretical modeling and identification of competence dimensions (31). Simultaneously, existing competencies and needs due to digitalization must be assessed (e.g., equipment provided by therapy centers). Finally, it is necessary to utilize theoretical evidence and practical field experience to develop appropriate offerings. However, questions remain
regarding the design and integration of this education into existing professionalization systems (e.g., universities, obesity trainer academies). After addressing initial questions, analyses of the correlations between therapist competency and therapy quality can be conducted, potentially leading to recommendations for enhancing the effectiveness of digital therapies.
Digital therapy is, on one hand, associated with increased investments in terms of necessary resources. For therapy preparation, this manifests in expenditures for hardware, software, technical consultation, and platform licenses. During therapy, centers incur additional costs due to paying therapists for extra hours during the introduction week, dual therapist presence during units, and additional efforts for assessing participants’ technical skills. On the other hand, cost savings arise from digitization. During therapy preparation and implementation, e.g., travel costs for therapy actors are eliminated. Moreover, therapist presence is reduced during asynchronous units. Existing reviews on economic evaluations of digital interventions for children and adolescents confirm that 82% of the studies reported cost savings due to media-based measures. However, variations in study designs, populations, and the size of intervention effects were noted (34). Therefore, future research must determine the cost-benefit ratio of KLAKSonline, followed by a comparison with traditional therapy concepts, to assess the advantages and disadvantages of digital therapy.

This protocol marks a pioneering effort on the digitalization of guideline-based (S3) and standardized (KgAS) obesity therapy in Germany. The described concept has been in pilot testing since January 2024, based on the Design-Based Research (DBR) approach, which includes an iterative process involving continuous cycles of design, implementation, evaluation, and refinement of the program. With a focus on usability, satisfaction of therapy actors and effectiveness, the KLAKSonline concept will be validated with two cohorts.
Although deriving conclusions may be challenging due to the pending validation, the following implications emerge. In outpatient therapy, KLAKSonline contributes to closing the existing care gap. When applied to inpatient therapy, self-directed learning with digital explainer videos could ease therapist burden and enhance participants’ capacity for applying learned skills to daily life. Beyond therapy, social pediatric centers could use digital platforms to facilitate the preparation and follow-up of therapy units. Moreover, the depicted therapy approach with its program parameters (e.g., framework conditions, digital methods) could extend to other target groups. Given that 53.5% of adults in Germany suffer from overweight and obesity, there is potential to develop digital programs with didactically modified teaching methods (30). The outlined components of digital therapy could also tackle obesity-related comorbidities. For this purpose, content must be adapted to address chronic conditions (type 2 diabetes, asthma). Additionally, the digital therapy program can be adapted for other German-speaking countries (Switzerland, Austria) by incorporating the respective national therapy guidelines and contents.
To integrate findings and implications into the healthcare landscape, challenges must be overcome. From a health policy perspective, it is crucial to clarify qualifications and certification required for therapists (e.g., data security, digital communication). Besides, an institutional monitoring of the therapist performance and patient satisfaction should be conducted. Additionally, questions regarding financing at the national level remain unresolved. Overcoming these challenges can help to close the care gap for adolescents with obesity and improve the healthcare system.

The authors acknowledge the support of Katja Warich and Thomas Wendeborn.

Conflict of Interest
All authors have completed the ICMJE Uniform Disclosure Form at www.icmje.org/coi_disclosure.pdf and declare no conflict of interest.

Funding
Funding for KLAKSonline was provided by grants from the Deutschen Fernsehlotterie [Funding ID 2022-0232]. The Deutsche Fernsehlotterie had no role in implementation of this study.

Ethical Approval and Informed Consent
This article did not necessitate review by Leipzig University or any IRB boards, as this work targeted a theoretical conceptualization of an intervention. No human subject or uniquely identifying information is included.

Data Availability
All data generated during this study are included in this article. Further inquiries can be directed to the corresponding author.

The prevalence of overweight and obesity is rising, especially among children and adolescents without access to therapy centers from rural regions. To address this care gap, this study aims to design the first German theory-based digital obesity therapy for 12- to 17-year-olds, accessible regardless of location.
For this purpose, a 12-month therapy concept was theory-based developed, based on existing planning and didactic models and aligned with German guidelines. It comprises 158 units: 89 synchronous units via videoconferences and 69 asynchronous units (regardless of time) via explainer videos, expert videos, and digital worksheets.