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Overweight and obesity are among the most pressing public health challenges of the 21st century, posing significant health risks and economic burdens worldwide []. According to the World Health Organization (WHO), the prevalence of adult obesity has more than doubled since 1990 []. By 2022, 43% of adults aged ≥18 years were classified as overweight, and 16% were living with obesity, making it a major risk factor for several chronic diseases, including cardiovascular disease, type 2 diabetes, musculoskeletal disorders, and cancer []. Data shows that being overweight or obese is associated with approximately 2.8 million deaths each year []. This highlights the urgent need for effective interventions to manage body weight (BW) and improve body composition in adults with excess body fat.
Physical activity (PA) is recognized as a critical component of obesity prevention and management strategies []. The WHO guidelines recommend that adults engage in at least 150 to 300 minutes of moderate-intensity aerobic activity or 75 to 150 minutes of vigorous-intensity activity per week []. It has been well documented that adherence to these recommendations is associated with significant improvements in body composition [], emphasizing the critical role of PA in mitigating obesity-related health issues. Despite its proven benefits, adults often struggle to maintain sufficient levels of PA due to barriers such as time constraints, lack of access to fitness facilities, and motivation, highlighting the need for innovative solutions that make PA and exercise more accessible and sustainable [].
Today’s digital world represents a transformative change in how we live, work, and interact [], characterized by the integration of digital technologies into almost every aspect of human life. One of the most significant outcomes of this technological revolution is the expansion of mobile apps, which have become integral tools in daily life. An app is defined as software designed for specific tasks, which can be downloaded and installed on mobile phones or other digital devices []. In recent years, the advancement of digitalization has led to the emergence of digital health interventions as promising tools for supporting BW management and promoting healthy lifestyles []. Among these, PA and fitness apps have gained considerable attention by leveraging technological advancements to offer and deliver exercise plans, while also monitoring PA and fitness progress [].
Over the past 2 decades, several studies have examined the effectiveness of health and fitness apps in BW management and other health outcomes [-]; however, the results have been inconsistent, with some studies reporting significant benefits while others found minimal or no effect on target outcomes. This variability in results may be attributed to differences in study design, population characteristics, app features, and intervention characteristics. More importantly, existing studies on digital PA and exercise interventions often lack a standardized implementation of key exercise characteristics (such as type, frequency, duration, and intensity) based on international PA guidelines. This inconsistency makes it difficult to compare interventions and assess their adequacy, thereby potentially influencing the outcomes. Therefore, a comprehensive review of digital PA interventions that are based on PA guidelines, such as those from the WHO or an equivalent framework, is needed to ensure more consistent and reliable outcomes.
ObjectivesThe primary objective of this systematic review was to evaluate the effectiveness of digital exercise interventions that were based on international PA recommendations on body composition, as well as PA and fitness outcomes, in adults with overweight and obesity. In addition, while this review aimed to identify gaps in the literature, its overarching goals were to provide insights that inform clinical practice and public health initiatives, and to guide the design of future digital interventions, thereby contributing to the effective management of overweight and obesity on a broader scale.
This systematic review and meta-analysis was conducted in accordance with the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines []. The PRISMA checklist was used to guide the reporting across all stages of the review, encompassing the formulation of the research question, establishment of eligibility criteria, development of the search strategy, study selection, data extraction, and synthesis of results. The review protocol was registered prospectively in the PROSPERO under the registration number CRD42024620020. The protocol’s title was revised during the review process; however, no other deviations from the registered protocol occurred.
Eligibility CriteriaThe eligibility criteria encompassed multiple dimensions guided by the population, intervention, comparison, outcome, and study design framework [], along with additional considerations. The population of interest comprised adults aged ≥18 years with overweight or obesity. Overweight and obesity were defined using established thresholds: a BMI ≥25.0 kg/m2 [] or ≥23.0 kg/m2 for Asia-Pacific adult populations [], body fat percentage (BF%) ≥25% for male individuals and ≥36% for female individuals [], or a waist-to-hip ratio (WHR) ≥0.90 for male individuals and ≥0.80 for female individuals []. Baseline measures of BW status had to be objectively assessed; studies relying on self-reported anthropometric data were excluded. To ensure the feasibility of participation in PA and exercise interventions, studies were required to include participants without severe health conditions or physical limitations that could hinder PA and exercise engagement. Studies involving trained participants who had been regularly engaged in PA, exercise, or sports within the 3 months before the intervention were also excluded. Furthermore, studies were excluded if they included participants who were pregnant or within 1 year postpartum, as these conditions can significantly influence body composition.
Regarding the intervention criteria, the review targeted interventional studies assessing the effectiveness of digital PA and exercise programs designed in alignment with WHO guidelines on PA, that is, a minimum of 150 minutes of moderate-intensity PA or 75 minutes of vigorous-intensity PA per week [], or a comparable framework. “PA” refers to any bodily movement produced by skeletal muscles that requires energy expenditure, while “exercise” or “physical exercise” is a subset of PA that is planned, structured, and repetitive, with the specific objective of achieving or maintaining health and fitness [,]. Eligible studies implemented PA or exercise interventions with a minimum duration of 8 weeks. In controlled trials, the control group (whether consisting of participants not engaging in physical exercise or those who did not engage in any digital interventions) was considered the comparator. For single-arm interventional studies, comparisons were made against baseline values of the same participants assessed before the intervention.
The primary outcomes of interest included anthropometric and body composition measures: BW, BMI, BF%, fat mass (FM), waist circumference (WC), and WHR. All outcomes had to be objectively measured; studies relying on self-reported data were excluded to minimize bias and ensure reliability. Any study that reported at least one of these outcomes was eligible for inclusion. The secondary outcomes included PA-related or physical fitness variables, regardless of the assessment method. Finally, eligible studies were restricted to publications in English or German, and no limitations were applied regarding the publication period, context, setting, or geographic location.
Information Sources and Search StrategyA comprehensive search strategy was used to identify relevant studies for inclusion in this systematic review, conducted from October 1 to 10, 2024. The databases searched included PubMed, Cochrane Library, Web of Science, and Ovid MEDLINE. The search strategy used a combination of keywords and Medical Subject Headings (MeSH) terms with the Boolean operators “AND” and “OR,” as detailed in . In addition to the database searches, the reference lists of the included studies and relevant review articles were manually reviewed to identify any additional publications that may not have been captured in the database search.
Study Selection and Data ExtractionThe study selection process was conducted using Covidence, a specialized tool for systematic screening and data extraction. Two independent reviewers (MM and DT) screened the titles and abstracts of all retrieved articles based on the predefined eligibility criteria. Any discrepancies between the 2 reviewers were resolved through discussion. Articles deemed potentially relevant during the abstract screening phase underwent full-text review, and the same reviewers thoroughly assessed the full text of each article, while reasons for exclusion were documented. A third reviewer (CD) was consulted for the final decision if consensus could not be reached. Studies that met all the eligibility criteria during the full-text screening process advanced to the data extraction phase, where the same reviewers extracted the data. The extracted data encompassed several domains, including study characteristics, study design, intervention details, sample size, population, app or digital tool specifics, PA or exercise protocols, comparators, anthropometric and body composition outcomes, and PA and fitness outcomes. When the data were unclear, incomplete, or missing, the reviewers contacted the authors of the studies to request clarifications or additional information. When multiple articles reported the same study with identical population, outcomes, and data, the earliest publication was included to avoid data duplication. Any exclusions were carefully considered and documented to ensure transparency in the selection process.
Risk of Bias AssessmentThe risk of bias in the included studies was assessed using standardized tools to ensure a thorough evaluation of methodological quality. Two independent reviewers (MM and DT) assessed the risk of bias, and any discrepancies were resolved through discussion. For randomized controlled trials (RCTs), the Cochrane Risk of Bias (version 2) tool was used []. This tool evaluates bias across 5 key domains: randomization process, deviations from intended interventions, missing outcome data, measurement of the outcome, and selection of the reported result. Each domain is assessed for potential sources of bias that could impact the validity of the trial’s findings. The Risk of Bias in Nonrandomized Studies of Interventions tool was used for nonrandomized and single-arm studies []. This tool evaluates 7 domains: confounding, selection of participants, classification of interventions, deviations from intended interventions, missing data, outcome measurement, and selection of the reported result. Using both tools enabled a comprehensive assessment of the methodological rigor and potential biases in each study, ensuring a reliable interpretation of the evidence.
Data SynthesisA qualitative synthesis of the data was conducted, focusing on the various outcomes reported across studies. The extracted data were systematically grouped and analyzed by outcome categories and variables (study design, population, study group, app or digital tool, intervention, primary outcomes, and PA outcomes), enabling a detailed exploration of trends and patterns in the evidence. The synthesis aimed to identify consistent trends across studies while also highlighting areas of agreement, inconsistencies, or discrepancies in the findings. This approach provided a deeper understanding of the broader implications of the data and helped identify areas where further research is needed to resolve conflicting results or clarify uncertainties.
Meta-analysis was performed using R (version 4.5.0; R Foundation for Statistical Computing) to evaluate the effects of digital exercise interventions on primary outcome variables. A random-effects model with Hartung-Knapp adjustment was applied to account for potential between-study heterogeneity and to provide robust CIs. The primary effect size metric was the mean difference (MD) between intervention and control groups, expressed in the original units for each outcome. Subgroup analyses were conducted to examine potential differences in intervention effects by control type. Studies were stratified based on the type of control condition: (1) active controls (ie, nondigital interventions or usual care) and (2) passive controls (ie, waitlist—participants assigned to receive the intervention after the study period—or no intervention). When studies included multiple eligible intervention arms, each arm was treated as a separate unit of analysis to avoid statistical dependency, with the intervention arm serving as the unit of analysis. Heterogeneity was assessed using the I2 statistic, τ2, and Cochran Q test. All procedures were conducted following the PRISMA guidelines, and results are reported with 95% CIs and corresponding P values.
A total of 4948 studies were initially identified through the databases and reference sources. After removing duplicates, 68.21% (3375/4948) of the studies were screened by title and abstract, of which 5.57% (188/3375) of the studies were retrieved for full-text review. Ultimately, 30 studies met the predefined eligibility criteria and were included in the systematic review. presents the PRISMA flowchart outlining the study selection process.
Figure 1. PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) flowchart showing the study identification, screening, and inclusion process. Included StudiesThe final sample of included studies consisted of 26 RCTs and 4 nonrandomized studies. Out of the 30 included studies, 11 (37%) were conducted in the United States, 3 (10%) in Australia, 3 (10%) in Korea, 2 (7%) in the United Kingdom, 2 (7%) in Germany, 2 (7%) in Spain, and 1 (3%) each in Sweden, France, Canada, Belgium, Singapore, China, and Hong Kong. The sample sizes varied from 16 to 750 participants, with an average of 132 participants. Of the 30 included studies, 6 (20%) exclusively included female participants, while none of the included studies focused solely on male participants. provides a summary of the characteristics of the studies included in the review.
Table 1. Summary of the characteristics and outcomes of the studies included in the systematic review. The studies are ordered by intervention duration.Study, year, and countryDesign and populationStudy groupsInterventionPrimary outcomes and findingsPAa outcomes and findingsIntervention duration: 24 monthsaPA: physical activity.
bRCT: randomized controlled trial.
cBW: body weight.
dBF%: body fat percentage.
eFM: fat mass.
fLPA: light physical activity.
gMVPA: moderate to vigorous physical activity.
hmHealth: mobile health.
iNot available.
jWC: waist circumference.
kWHR: waist-to-hip ratio.
lMPA: moderate physical activity.
mVPA: vigorous physical activity.
Qualitative Data SynthesisThe duration of the interventions ranged from 8 weeks to 24 months, with an average of 6.6 (SD 5.5) months. Although all studies included interventions involving PA or exercise through action planning, coaching, or goal setting, there were substantial variations in the PA-related methods and techniques used, as well as in the inclusion of other lifestyle components alongside PA. A total of 14 studies [,-,,,,-,,,] used digital interventions that delivered structured physical exercise programs, while other studies included flexible PA or exercise routines based on international guidelines. Regarding the type of physical exercise, all studies incorporated aerobic or moderate to vigorous PA (MVPA) as a core component, while 13 studies [,,,-,,,-,,] additionally included resistance or strength training. All but 3 studies [,,] incorporated multiple lifestyle components, including diet, sleep, and stress management, with diet being the most commonly used component alongside PA. Dietary guidance was provided in the form of dietary plans, goal setting based on dietary guidelines, nutritional advice, dietary coaching, and behavior change strategies related to eating habits.
Various digital tools, including mobile apps, websites, wearable devices, telecommunication platforms (eg, videoconferencing), virtual reality, or a combination of 2 or more in most studies, were used in the interventions. These tools supported features such as program delivery, coaching, feedback provision, goal setting, tracking, and progress monitoring. They were implemented in various ways, including automated or manual feedback, self-guided or professionally guided programs, real-time or asynchronous coaching, gamification elements, integration with other health platforms, and different levels of interactivity. This resulted in a diverse range of intervention designs, delivery modes, and user engagement levels.
While 4 studies [,,,] used a single-arm design, the control groups in the other studies exhibited considerable variability, including active controls (such as alternative digital or nondigital interventions or usual care) [,,-,,,,,,-], passive control (such as no intervention or waitlist group) [,,], or a combination of both [,,,], reflecting a diversity in methodological designs and approaches. All single-arm design studies demonstrated a significant reduction in outcome variables. Similarly, interventional studies comparing digital interventions to passive controls showed favorable effects. However, in studies comparing experimental groups to nondigital active controls, the results were inconsistent, with some reporting greater reductions in outcome variables following digital interventions [,,,,,,], while others found no significant difference [,,-,,], and one [] even reported less reduction following digital interventions. Common nondigital interventions included educational booklets, self-care advice, and in-person physical exercise programs.
Among the studies included in this review, 25 evaluated BW as an outcome variable. Overall, 22 studies (with an average intervention duration of 6.5, SD 4.9 months, ranging from 8 weeks to 24 months) reported significant BW reduction (range −1.3 to −8.4 kg) following digital intervention programs [,,,-,-,,,], while 3 studies found no significant change in BW following a 12-week multicomponent telerehabilitation program [], a 12-week smartphone mirroring-based telepresence exercise program [], or a 24 months of mobile health (mHealth) intervention []. A total of 10 studies (with an average intervention duration of 9.0, SD 8.4 months, ranging from 3 to 24 months) found significant differences in postintervention BW between their study groups [,,,,,,-,], most of which used active control groups, with one study [] using passive controls and another [] using a combination of both. However, 10 studies (with an average intervention duration of 4.7, SD 1.7 months, ranging from 8 weeks to 6 months) reported no significant between-group differences in BW [,,-,,-,], most of which used active control groups, with one study [] using passive controls and another [] using a combination of both. No clear pattern was observed in BW outcomes when comparing experimental groups to nondigital active controls, with some studies reporting greater BW reduction following digital interventions [,,,,], while others found no significant difference [,-,] or reported less BW reduction following digital interventions [].
In this review, 23 studies examined BMI as an outcome measure. In total, 19 studies (with an average intervention duration of 5.9, SD 5.2 months, ranging from 8 weeks to 24 months) observed a significant reduction in BMI (range −0.4 to −3.4 kg/m2) following digital intervention programs [,,,,,,,,-,,,,], while 4 studies (with an average intervention duration of 5.1, SD 4.6 months, ranging from 10 weeks to 12 months) reported no significant BMI change following digital interventions [,,,]. A total of 8 studies (with an average intervention duration of 4.6, SD 3.4 months, ranging from 8 weeks to 12 months) reported significant differences in postintervention BMI between study groups [,,,-,,], most of which used active control groups, while one study [] used passive controls and 2 others [,] used a combination of both. However, 9 studies (with an average intervention duration of 6.3, SD 6.8 months, ranging from 10 weeks to 24 months) found no significant between-group differences in BMI changes [,,,,,,-], most of which used active control groups, with one study [] using passive controls and another [] using a combination of both. No clear trend was observed in BMI outcomes when comparing experimental groups to nondigital active controls, with some studies reporting greater BMI reduction following digital interventions [,,,,], while others found no significant difference [,,].
A total of 16 studies examined WC as an outcome measure. Overall, 15 studies (with an average intervention duration of 5.7, SD 3.0 months, ranging from 8 weeks to 12 months) found a significant reduction in WC (range −2.1 to −9.2 cm) following digital intervention programs [,,,-,,,,,,,,,], while one study [] showed no significant change following a 3-month multicomponent lifestyle intervention delivered via a mobile app. In total, 8 studies (with an average intervention duration of 5.3, SD 3.1 months, ranging from 8 weeks to 12 months) reported significant between-group differences in postintervention WC [,,,,-,]; however, 5 studies (with an average intervention duration of 5.4, SD 1.3 months, ranging from 12 weeks to 6 months) indicated no significant between-group differences [,,,,]. There was also no clear trend in WC outcomes when comparing experimental groups to nondigital active controls, with 3 studies [,,] reporting greater WC reduction following digital interventions, while 3 others [,,] found no significant difference. WHR was assessed in 6 studies, with 2 studies (conducting 6-month and 3-month interventions) reporting a significant reduction in WHR (−0.02 and −0.01, respectively) [,], while the other 4 studies (with an average intervention duration of 6.0, SD 4.2 months, ranging from 12 weeks to 12 months) found no change in WHR following digital intervention programs [,,,].
In this review, FM was examined as an outcome measure in 7 studies (with an average intervention duration of 7.9, SD 7.8 months, ranging from 8 weeks to 24 months), all of which found a significant reduction (range −0.4 to −6.5 kg) following digital intervention programs [,,,,,,]. Among them, 3 studies (with an average intervention duration of 3.5, SD 2.2 months, ranging from 8 weeks to 6 months) reported significant between-group differences after the intervention [,,], while 3 others (with an average intervention duration of 11.0, SD 11.3 months, ranging from 12 weeks to 24 months) found no significant difference in FM between their study groups [,,]. In terms of BF%, 9 studies measured this outcome (with an average intervention duration of 6.8, SD 7.1 months, ranging from 8 weeks to 24 months), all of which found a significant reduction (range −0.3% to −4.1%) from pre- to posttests in digital intervention groups [,,,,,,-]. However, the majority (8 studies) reported no significant between-group differences in BF% changes, and one study [] followed a single-arm design. No clear trend was observed in FM and BF% outcomes when comparing digital-based experimental groups to nondigital active controls.
Regarding PA, 8 studies provided information on changes in MVPA following digital interventions, with 4 reporting significant improvements with an average intervention duration of 9.2 (SD 9.9; range 3-24) months [,,,] and the other 4 observing no change in MVPA with an average intervention duration of 5.2 (SD 1.5) months [,,,]. A similar trend of inconsistent results was observed across other PA-related variables, including general PA [,,-], light PA [,,], moderate PA [,], vigorous PA [,], daily steps [,,], grip strength [,,], and the 6-minute walk test [,]. In addition, 5 other variables, including exercise capacity [], exercise fun [], exercise self-efficacy [], sit-to-stand test [], and gait speed [], were each assessed in just one study. Inconsistent trends in postintervention changes were observed in these variables, with some showing significant improvements [,,], while others displayed no significant changes [], and some revealed mixed results within individual studies [,].
Meta-AnalysisA total of 26 intervention arms from 19 independent studies were included in the meta-analysis assessing the effect of digital exercise interventions on BW. The overall pooled analysis revealed a significant reduction in BW following digital exercise interventions compared to control conditions (MD=−1.17 kg, 95% CI −1.92 to −0.43; P=.003; t25=−3.25). Heterogeneity was not significant (I2=0.0%; τ2=1.35; P=.49), indicating consistency across studies. Subgroup analyses based on control type showed a greater effect in studies comparing digital interventions to active (nondigital) controls than to passive controls (MD=−1.23 kg vs −0.52 kg, respectively). [,,,,,,,,,,,-] shows the results of the meta-analysis assessing the effect of guideline-based digital exercise interventions on BW.
Regarding BMI, a total of 26 intervention arms from 17 independent studies were included in the meta-analysis. A random-effects model revealed a statistically significant reduction in BMI favoring digital interventions (MD=−0.50 kg/m2, 95% CI −0.82 to −0.19; P=.003; t25=−3.32), with significant heterogeneity across studies (I2=70.0%; τ2=0.40; P<.001). Subgroup analyses based on control type showed a greater effect in studies comparing digital interventions to passive controls than to active (nondigital) controls (MD=−0.70 kg/m2 vs −0.45 kg/m2, respectively). [,,,,,,,,-,,,] shows the results of the meta-analysis assessing the effect of guideline-based digital exercise interventions on BMI.
Regarding BF%, a total of 7 intervention arms from 6 independent studies were included in the meta-analysis. The overall analysis revealed no statistically significant difference between interventions and control conditions (MD=−0.08%, 95% CI −0.94 to 0.79; P=.84, t6=−0.21). Heterogeneity was not significant (I2=7.4%; τ2=0.25; P=.37). [,,,,,] shows the results of the meta-analysis assessing the effect of guideline-based digital exercise interventions on BF%.
Figure 2. Forest plot showing the effect of guideline-based digital exercise interventions on body weight across 26 comparisons between digital exercise interventions and control conditions, using a random-effects model with Hartung-Knapp (HK) adjustment. Subgroup analyses are presented for comparisons with nondigital active controls (21 comparisons) and passive controls (5 comparisons), while the last model represents a pooled analysis of all studies (n=1709 intervention participants vs n=1712 controls). Each horizontal line represents a study’s 95% CI, with diamond shapes reflecting the pooled estimates. DPI: diet and physical activity intervention; En-Tech: enhanced technology; IC: intensive counseling; LIC: less intensive counseling; MD: mean difference; mHealth: mobile health; PC: personal coaching; PI: physical activity intervention; SP: smartphone. 
Figure 3. Forest plot showing the effect of guideline-based digital exercise interventions on BMI across 26 comparisons between interventions and control conditions, using a random-effects model with Hartung-Knapp (HK) adjustment. Subgroup analyses are presented for comparisons with nondigital active controls (20 comparisons) and passive controls (6 comparisons), while the last model represents a pooled analysis of all st
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