Childhood obesity is rising at an alarming rate worldwide. According to the World Health Organization [1], an estimated 35 million children under the age of 5 years are overweight, and the prevalence of children and adolescents with overweight aged 5 to 19 years has risen significantly from 8% in 1990 to 20% in 2022. This surge in childhood obesity not only results in health-related comorbidities such as metabolic syndrome and orthopedic issues but also significantly affects children’s psychological well-being, body image, and overall quality of life [2]. In the long term, these children also have a moderate risk of obesity persisting into adulthood [3], along with its cardiovascular complications.

Numerous studies have shown that children’s eating habits [4] and food preferences [5] are strongly linked to their body composition, with unhealthy diets and poor feeding practices increasing the risk of childhood obesity. Importantly, these dietary patterns often persist into adulthood as feeding practices established in early life influence future dietary and taste preferences [6,7]. Therefore, timely interventions during early childhood, particularly those aimed at shaping healthy feeding behaviors, are critical for long-term obesity prevention and for promoting sustainable, healthy growth trajectories [8]. Parents play a central role in this process [9]. From infancy, they influence not only the types and amounts of food offered to children but also the emotional and environmental context in which meals take place [10]. As a result, many public health initiatives encourage parents to act as “health promoters” shaping their child’s feeding behaviors and long-term food preferences through informed and consistent modeling and support [11,12].

However, providing parents with consistent, evidence-based support remains challenging. Traditional interventions targeting feeding behaviors, such as in-person counseling and motivational interviewing, have shown benefit but are often labor-intensive, time-consuming, and difficult to scale [13]. With the advent of technological advancements, digital interventions such as mobile health (mHealth) apps have gained traction as a means of expanding outreach to parents and providing accessible, around-the-clock support for improving dietary choices and feeding behaviors [11]. For instance, a recent pilot study evaluating a parent-focused mHealth app designed to promote healthy eating behaviors in children found that parents perceived the app as helpful in increasing their nutritional knowledge and awareness of their children’s diet [12]. Similar digital interventions in adult populations have also shown promise, with meta-analyses highlighting their effectiveness in managing and preventing obesity [14]. However, despite these benefits, commercially available mHealth apps still lack medical oversight, are not co-designed by stakeholders including health care professionals and end users, and often fall short in providing evidence-based or culturally tailored content [15,16]. These drawbacks limit their effectiveness and credibility, particularly when used as stand-alone tools for behavior change. In addition, given that cultural influences strongly shape feeding practices [17], there is a clear need for digital solutions that are evidence based, medically guided, and culturally sensitive, with the eventual aim of reinforcing good dietary practices and habits in the pediatric population.

To this end, our study team involving a diverse panel of domain experts, including neonatologists, pediatricians, dietitians, speech therapists, physiotherapists, and nurses, developed a digital health app named Feeding, Lifestyle, Activity Goals (FLAGs) to promote healthier eating behaviors and lifestyle habits in infants from birth to the age of 2 years. Its development involved a meticulous process for which the questionnaires and advisory content underwent extensive curation [18]. The tool is grounded in theoretical frameworks such as the capability, opportunity, and motivation–behavior framework, which emphasizes enhancing parents’ capabilities through skill-building, while providing opportunities and motivation via a user-friendly app to support behavioral change and promote healthy feeding habits. Overall, FLAGs serves as both an assessment tool and a provider of tailored advice for parents on their infants’ feeding practices, sedentary behavior, and physical activity. In this study, we specifically aimed to perform a mixed methods evaluation of the app’s usability and acceptability among end users. These findings will inform iterative refinements and subsequent large-scale trials to examine the app’s efficacy in effecting behavior change and on anthropometric outcomes.

This study evaluated the usability and acceptability of an mHealth app designed to support parents of infants aged 3 weeks to 23 months with evidence-based resources and personalized advice on feeding, physical activity, and growth. Overall, the digital health app demonstrated good usability, as evidenced by the mean SUS score. This places FLAGs in a range consistent with functional but improvable health technology [19]. In terms of acceptability, parents emphasized several positive aspects of the app, suggesting that it was generally well accepted within the study population. In particular, parents valued the structured organization of caregiving tasks, the ability to visualize progress, and the provision of evidence-based feedback in real time. These features created a sense of confidence and empowerment, particularly for first-time parents and for those balancing multiple caregiving roles. Many participants expressed that FLAGs offered reassurance and guidance that might otherwise be unavailable between clinical encounters, reflecting both the app’s acceptability and its potential to bridge gaps in routine parenting support. Challenges, particularly on the usability front, still remain and will guide subsequent work to improve the app’s usability. For example, the interface was perceived to be occasionally unintuitive, and data entry, while comprehensive, was regarded as burdensome and overly manual, limiting sustained engagement in day-to-day use. Advisory content was sometimes experienced as verbose, which risked diluting its impact and reducing its immediate applicability. Frequently suggested improvements included the ability to share access across multiple caregivers, streamlined logging features such as photo uploads and visual timers, and the capacity to archive and retrieve past assessments. Taken together, these findings suggest that FLAGs has achieved sufficient baseline usability and acceptability to justify further development, with a road map for further iteration.

When considered in relation to the wider literature, our findings reinforce both the promise and the challenges of parent-facing digital health interventions in early childhood, consistent with evidence from preschool interventions. For example, the MINISTOP (Mobile-Based Intervention Intended to Stop Obesity in Preschoolers) trial demonstrated improvements in composite diet and activity behaviors among children aged 4 years, underscoring the feasibility of app-based parent engagement [13]. Similarly, the Food4toddlers study revealed that parental access to the Food4toddlers website improved the frequency of intake of vegetables among toddlers immediately after the 6-month intervention period ended [27]. Building on these works, the Early Food for Future Health trial noted that an internet-based tool for parents of children aged between 6 and 12 months was appropriate and feasible to propagate information on healthy infant feeding to Norwegian mothers, leading to an increase in young children’s daily vegetable and fruit intake [28]. More generally, meta-analyses confirm that digital health interventions can promote healthier nutrition behaviors in children and families [11] and are effective in weight management among adults [14]. At the same time, reviews of pediatric nutrition apps have raised concerns regarding lack of clinical input, inadequate behavior change mechanisms, and poor usability [15,16]. A scoping review on child health promotion apps by Blakeslee et al [29] similarly acknowledged the importance for apps to be grounded in transparent theoretical frameworks and that content should be tailored to include intuitive and adaptive features—all challenges mirrored by parents’ feedback in our study calling for clearer, more targeted content and more usable logging. These findings highlight a key point: effectiveness is unlikely to be determined by the presence of digital content alone but rather by the integration of evidence-based content, clinical oversight, and user-centered design.

Our findings carry several implications for future iterations of FLAGs and design of similar interventions. First, minimizing interaction burden is likely to be critical for engagement. Parents consistently requested features that reduce repetitive manual data entry, such as preset options for routine inputs, auto-suggestions, and smart defaults [20,21]. Incorporating semipassive data capture where feasible could further enhance efficiency and lower friction. Second, personalization emerged as a strong driver of acceptability. Tailoring advisory content to infant age, feeding stage, and parent preferences and delivering messages in concise, layered formats would likely improve both perceived relevance and usability [29,30]. Third, supporting the broader caregiving ecosystem will be essential. Parents emphasized the need for shared caregiver accounts, secure photo uploads, and archival functions that support continuity of care, reflecting the reality that infant caregiving is rarely the responsibility of a single individual. Embedding FLAGs into routine pediatric follow-up visits such as growth monitoring or immunization appointments may normalize its use and provide opportunities for light-touch reinforcement by clinicians without imposing additional workload. Finally, equity considerations must be foregrounded in subsequent iterations, including the development of multilingual content, culturally appropriate guidance, offline-tolerant features, and accessible visual design.

Moving forward, our study team intends to evaluate the efficacy of the FLAGs app through a randomized controlled trial (NCT06457750) in improving anthropometric outcomes and establish its broader behavioral and health impacts [30]. This prospective interventional study aims to examine changes in infant feeding practices; mealtime routines; and anthropometric outcomes such as weight-for-length, BMI, and adiposity. Incorporating validated behavioral scales such as the Baby Eating Behavior Questionnaire and Children’s Eating Behavior Questionnaire [31] alongside growth metrics would provide a robust assessment of efficacy. Equally important will be the systematic evaluation of mediators (such as engagement dose and message exposure) and moderators (such as parity and baseline feeding difficulties). Use analytics, including log-in frequency, feature taps, and completion of advisories, should be analyzed a priori to explore “dose-response relationships” and fidelity of engagement [20,21,30]. Such an approach would advance understanding of not only whether the app works but also how it works and for whom it is most effective.

This study has several strengths. The FLAGs digital health app was developed through a clinically informed, framework-based process integrating evidence-based recommendations with input from health care professionals. The mixed methods design is a comprehensive process of evaluation that allowed for triangulation of quantitative and qualitative insights, enriching interpretation and ensuring that usability ratings were contextualized by lived experiences. Rigorous qualitative analysis procedures, including independent coding, consensus discussions, and audit trails, enhanced the trustworthiness of the findings.

Nevertheless, several limitations should be acknowledged. The sample was small, clinic based, and restricted to English-speaking participants, which limits generalizability. The 7-day evaluation period was limited in duration and did not permit the assessment of long-term engagement or sustained behavioral effects. Outcomes relied primarily on self-report, introducing potential recall and social desirability biases, whereas the clinic-based recruitment may have contributed to selection bias. These constraints are typical of a pilot study but must be addressed in future work. Larger and more diverse samples; extended follow-up; and incorporation of objective measures, including food photo diaries and automated tracking of physical activity, will be useful in validating these findings and evaluating real-world impact.

In conclusion, our pilot study showed that FLAGs, a medically guided digital health app, was deemed to be usable and acceptable by target end users, providing structured, evidence-based support for infant feeding and lifestyle practices while identifying areas for refinement such as data entry, personalization, and multicaregiver access. With further system and interface optimization, as well as robust evaluation of its efficacy in a subsequent interventional study, our tool has potential as a scalable strategy to promote healthy routines in early life and support obesity prevention.