JMIR J Med Internet Res Journal of Medical Internet Research 1438-8871 JMIR Publications Inc. Toronto, Canada v17i7e181 26199208 10.2196/jmir.3921 Review Review Evaluation of Internet-Based Interventions on Waist Circumference Reduction: A Meta-Analysis Eysenbach Gunther Mehring Michael van Genugten Lenneke Seo Dong-Chul PhD 1
College of Health Sciences Department of Health Education and Management Ewha Womans University Human Ecology Building 204 52, Ewhayeodae-gil, Seodaemun-gu Seoul, 120-750 Republic Of Korea 82 2 3277 2580 82 2 3277 2867 dseo@ewha.ac.kr
http://orcid.org/0000-0002-1972-6237 Niu Jingjing MS 2 http://orcid.org/0000-0001-9812-2548 1 College of Health Sciences Department of Health Education and Management Ewha Womans University Seoul Republic Of Korea 2 School of Public Health Department of Applied Health Science Indiana University Bloomington, IN United States Corresponding Author: Dong-Chul Seo dseo@ewha.ac.kr 07 2015 21 07 2015 17 7 e181 6 10 2014 11 2 2015 5 3 2015 31 5 2015 ©Dong-Chul Seo, Jingjing Niu. Originally published in the Journal of Medical Internet Research (http://www.jmir.org), 21.07.2015. 2015

This is an open-access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work, first published in the Journal of Medical Internet Research, is properly cited. The complete bibliographic information, a link to the original publication on http://www.jmir.org/, as well as this copyright and license information must be included.

 Background

Internet-based interventions are more cost-effective than conventional interventions and can provide immediate, easy-to-access, and individually tailored support for behavior change. Waist circumference is a strong predictor of an increased risk for a host of diseases, such as hypertension, diabetes, and dyslipidemia, independent of body mass index. To date, no study has examined the effect of Internet-based lifestyle interventions on waist circumference change.

 Objective

This study aimed to systematically review the effect of Internet-based interventions on waist circumference change among adults.

 Methods

This meta-analysis reviewed randomized controlled trials (N=31 trials and 8442 participants) that used the Internet as a main intervention approach and reported changes in waist circumference.

 Results

Internet-based interventions showed a significant reduction in waist circumference (mean change –2.99 cm, 95% CI −3.68 to −2.30, I2=93.3%) and significantly better effects on waist circumference loss (mean loss 2.38 cm, 95% CI 1.61-3.25, I2=97.2%) than minimal interventions such as information-only groups. Meta-regression results showed that baseline waist circumference, gender, and the presence of social support in the intervention were significantly associated with waist circumference reduction.

 Conclusions

Internet-based interventions have a significant and promising effect on waist circumference change. Incorporating social support into an Internet-based intervention appears to be useful in reducing waist circumference. Considerable heterogeneity exists among the effects of Internet-based interventions. The design of an intervention may have a significant impact on the effectiveness of the intervention.

 waist circumference obesity adiposity Internet intervention studies Introduction

The prevalence of obesity has been increasing worldwide for approximately 50 years and has now become a global pandemic [1]. Lifestyle interventions balancing energy intake and energy expenditure have been suggested as effective tools to treat obesity and prevent obesity-related health burdens [2,3]. Internet-based interventions can provide immediate, easy-to-access, and individually tailored support for behavior change, which attract a large number of individuals, including the young or elderly, healthy, disabled or sick, and various ethnicities [4,5]. It has been reported that Internet-based lifestyle interventions can be as effective as phone- or person-based interventions in reducing body weight [6-8]. In contrast, Internet-based interventions are more cost-effective than conventional interventions [9-12].

Waist circumference, as a simple and effective measure of central obesity, is a strong predictor of an increased risk for hypertension, diabetes mellitus, dyslipidemia, metabolic syndrome, and coronary heart disease independent of body mass index (BMI) [13,14]. Changes in waist circumference in response to lifestyle interventions reflect changes in central obesity [15,16]. Studies have reported that waist circumference can be reduced while no significant changes in body weight occur [17-19]. Few studies, however, have systemically evaluated the effect of lifestyle interventions on waist circumference change. Therefore, this study examined the effect of Internet-based lifestyle interventions on waist circumference change.

Previous reviews have reported that Internet-based interventions can promote physical activity and significantly reduce body weight [2,20,21]. Khaylis et al [22] conducted a systematic review of efficacious technology-based weight-loss interventions and identified self-monitoring, counselor feedback and communication, social support, structured programs, and individually tailored programs as a key to successful interventions. In addition, the literature identified goal setting, motivational interviewing, and incentives as potential factors that increase intervention effectiveness [9,11,23-26]. Seo and Sa [27] also reported that the number of components was associated with the effect of lifestyle interventions. Based on the existing evidence, we hypothesize the following: (1) an Internet-based intervention can significantly reduce waist circumference; (2) Internet-based interventions reduce waist circumference more than conventional minimal interventions, such as those with usual care or information-only delivery; and (3) the number and type of components in lifestyle interventions are significantly associated with the effect on waist circumference change.

 Methods Search Strategy

An electronic search was performed in the following databases: Academic Search Premier, CINAHL Plus with Full Text, Educational Resource Information Center (ERIC), Health Source Nursing/Academic Edition, MEDLINE, PsycARTICLES, SPORTDiscus with Full Text Results, and ProQuest Dissertations and Theses A&I database. The search terms used various combinations of the following keywords or phrases: adiposity, weight, overweight, obese, obesity, lifestyle, nutrition, diet, intake, physical activity, exercise, eHealth, Web, online, email, electronic mail, Internet, social networking, treatment, therapy, interventions, management, trial, waist, central adiposity, random, control, and randomized controlled trial (RCT). After excluding ineligible studies, a manual search was conducted by screening the references of the remaining articles and contacting experts. The detailed search strategy can be found in Multimedia Appendix 1.

 Inclusion Criteria

Studies were selected if they met all of the following criteria: (1) published in English peer-reviewed journals between 1980 and April 2014 or dissertations/theses written in English that reported relevant yet unpublished results and were uploaded before April 2014, (2) studies based on RCTs, (3) studies that used the Internet as a major intervention tool in at least 1 arm, (4) studies that used lifestyle interventions (which promote healthy diet, physical activity, or both), (5) studies that reported the mean and standard deviation (SD) or standard error (SE) of the waist circumference, and (6) studies involving adults (aged ≥18 years). Studies were excluded if special diets or medications were used in the intervention or only follow-up data of an intervention were reported.

 Data Extraction

The following data were extracted from each included study and substudy: (1) general information, such as the name of the first author and year of publication/completion; (2) characteristics of the substudy, such as intervention location, number of participants, intervention length, frequency, retention rate, participants’ compliance, features of the intervention arm, approaches used in adjunction to the Internet (eg, personal contacts via phone, in-person visits, or other devices), intervention content, and whether or not theory, tailoring, self-monitoring and feedback on performance, goal setting, motivational interviewing, social support/social change, and incentives for weight loss were used in the intervention; (3) characteristics of the participants, such as general obesity status, reported existing diseases, mean age, and percentage of male participants; and (4) the mean and SD or SE of the waist circumference at baseline and immediately after the intervention, and the waist circumference change. The SE of the waist circumference change was calculated using the baseline and follow-up SD or SE, assuming an intracorrelation coefficient of 0.5 between pretest and posttest [28], when the SD or SE of the waist circumference change was not reported. The intention-to-treat analysis results were extracted and used when available. The risk of bias was assessed using the Cochrane Collaboration tool [29] and this assessment was used to guide the interpretation of study results.

 Data Analysis

Each reported arm was treated as an independent substudy. Treatments that were unlikely to have effects on waist circumference change, such as no intervention, delayed intervention, usual care, and information-only groups, were categorized as “minimal interventions.” Paper-, phone-, and person-based interventions were grouped together as “other interventions” because only 6 trials used any of these interventions. We calculated the overall effect sizes of waist circumference changes in Internet-based, minimal, and other interventions. Next, we compared the effects between Internet-based interventions with minimal or other interventions. To examine the effect of a “unique intervention component” on waist circumference changes, intervention components were coded as 0 for the component delivered in both conditions, 1 for the unique component in Internet-based intervention, and 2 for the unique component in minimal intervention. The number of times each intervention component was uniquely found only in Internet-based interventions was computed.

Effect sizes were presented as the mean waist circumference change in centimeters with a 95% confidence interval (CI). Funnel plot and Begg’s test were used to test publication bias. The I2 index was used to test between-study heterogeneity. A meta-regression was performed to identify characteristics that were significantly associated with differences in waist circumference changes between Internet-based interventions and minimal interventions, although it was likely underpowered. Due, in part, to the concern about the possible insignificant findings arising from low power, another meta-regression was performed for the waist circumference changes from baseline to posttest. The adjusted R 2 was calculated to present the predictive power of meta-regression models. Random effects models were used if significant between-study heterogeneity was detected. Analyses were performed using Stata 13 (StataCorp LP, College Station, TX, USA).

 Results Overview

After removing duplicates, the electronic search retrieved 83 articles and 26 dissertations or theses. The manual search retrieved 8 additional studies. Four studies indicated measurement of waist circumference, yet failed to report adequate information on the waist circumference. We contacted the authors but could not obtain additional information necessary for meta-analysis. Thus, these 4 studies were excluded from analysis. Figure 1 demonstrates the flow of the literature search. The studies were reviewed independently by 2 reviewers and any disagreement encountered was resolved by discussion.

Flow chart of literature search.

 Characteristics of Included Studies

This review includes 31 intervention trials involving 72 intervention arms and 8442 adults [6-12,23,25,30-51]. The number of total participants ranged from 21 to 1692, and the mean sample size was 272 per study. Four studies only recruited women and 5 studies only recruited men. Fifteen of 31 interventions were conducted in the United States. Among substudy participants, the mean age ranged from 19.0 to 64.9 years and the mean baseline waist circumference ranged from 81.7 to 128.4 cm. The intervention length ranged from 4 weeks to 2 years. The retention rate ranged from 21.7% to 100%, and the mean retention was 75.2%. Characteristics of the included substudies are provided in Table 1.

Descriptive data of substudies included in this meta-analysis (N=72).

Author Year Arm Features N Waist circumference (cm)
Baseline Post Δ Mean (SD)
Bennett [9] 2010 Minimala Brochure 50 N/A N/A –1.9 (10.8)
Internet Online program + forum 51 N/A N/A –1.9 (10.8)
Bischoff [30] 2010 Basic Internet-based Online program + email contacts 22 94.7 92.6 –2.1 (3.5)
Enhanced Internet-based Basic + goal setting 21 83.8 82.5 –1.3 (1.9)
Booth [10] 2008 Basic Internet-based Online PA program + forum + email feedbacks 26 96.9 N/A –4.5 (4.5)
Enhanced Internet-based Basic + nutrition component 27 95.6 N/A –3.2 (2.9)
Bukhari [31] 2009 Minimala One class + a counseling 11 98.8 100.6 1.8 (16.9)
Internet Online programs 16 107.5 101.8 –5.7 (14.6)
Carr [32] 2008 Minimala None 18 99.2 99.8 0.6 (2.1)
Internet Online sessions + email contacts 14 100.6 96.6 –4.0 (2.5)
Chambliss [33] 2011 Minimala None 28 100.1 N/A –0.6 (5.2)
Basic Internet-based Online monitor + email counseling 33 97.1 N/A –3.4 (4.6)
Enhanced Internet-based Basic + behaviorally tailored 34 98.2 N/A –2.8 (5.4)
Chen [34] 2013 Minimala None 31 88.9 88.3 –0.6 (10.2)
Internet Online program + feedbacks 32 91.9 88.4 –3.5 (11.1)
Chung [35] 2014 Minimala None 19 94.5 92.6 –1.9 (8.3)
Paper Logbook 16 93.2 89.1 –4.1 (7.1)
Internet Online logs + evaluation 19 91.9 88.5 –3.4 (11.0)
Collins [36] 2012 Minimala None 104 107.2 N/A 0.3 (3.1)
Basic Internet-based Online programs + forums + email contacts 99 106.9 N/A –2.6 (4.0)
Enhanced Internet-based Basic + personalized + feedbacks 106 106.6 N/A –3.2 (5.0)
Dekkers [37] 2011 Minimala None 49 101.7 99.2 –2.5 (8.9)
Phone Phone sessions + counseling 44 99.9 96.4 –3.5 (10.6)
Internet Online sessions + email counseling 48 102.9 99.4 –3.5 (11.3)
Hansen [38] 2012 Minimala None 585 89.6 89.1 –0.5 (8.4)
Internet Online program + forum 583 90.1 90.0 –0.1 (8.5)
Herrick [39] 2009 Minimal None 860 81.7 N/A 0.7 (4.7)
Internet Online programs + email reminders 832 81.9 N/A 0.3 (2.9)
Hunter [40] 2008 Minimala None 222 94.2 93.4 –0.4 (3.8)
Internet Online program + feedbacks 224 94.5 92.2 –2.1 (4.3)
Kang [41] 2010 Minimala General information 75 85.4 88.6 3.2 (8.8)
Basic Internet-based 1-year email education 25 83.2 84.3 1.1 (5.5)
Enhanced Internet-based 2-year email education 25 89.1 87.3 –1.8 (3.0)
Mehring [23] 2013 Minimala Usual care 77 110.9 104.4 –6.9 (6.9)
Internet Online programs 109 107.3 106.6 –2.4 (5.0)
Mobley [42] 2006 Basic in-person In-person counseling 32 100.7 99.3 –1.4 (9.1)
Enhanced in-person In-person counseling 33 101.8 98.5 –3.3 (9.7)
Basic Internet-based Online programs 29 102.7 102.4 –0.3 (10.1)
Enhanced Internet-based Online programs 29 101.6 103.4 1.8 (8.4)
Morgan [11] 2009 Minimala None 31 102.8 N/A –5.2 (5.4)
Internet Online programs + notice board + email feedbacks 34 103.4 N/A –4.4 (5.7)
Morgan [6] 2011 Minimal None 45 99.4 N/A 1.5 (4.5)
Internet Online program + email feedbacks 65 101.6 N/A –4.4 (4.8)
Morgan [43] 2013 Minimal None 52 113.6 N/A –0.8 (2.9)
Paper Books 54 112.6 N/A –3.7 (4.5)
Internet Online programs + email feedbacks 53 113.7 N/A –5.4 (5.2)
Patrick [12] 2011 Minimala Website with general health information 217 112.9 111.6 –1.3 (11.4)
Internet Online assessment + sessions + feedbacks + email counseling 224 113.7 112.1 –1.6 (11.4)
Pressler [44] 2010 Basic Internet-based Nonstructured 27 101.9 98.3 –3.6 (8.6)
Enhanced Internet-based Structured 50 100.5 98.0 –2.5 (7.8)
Pullen [45] 2008 Basic Internet-based Online program 8 98.1 96.2 –1.9 (6.5)
Enhanced Internet-based Basic + online discussions 8 91.1 85.7 –5.4 (6.4)
Rogers [7] 2012 Paper Group sessions 14 125.9 121.9 –4.0 (8.1)
Basic Internet-based Online programs 12 128.4 121.6 –6.8 (9.3)
Enhanced Internet-based Basic + Bluetooth 13 126.3 120.1 –6.2 (12.6)
Seely [46] 2013 Minimala None 13 N/A N/A –2.8 (2.3)
Internet Facebook support group 11 N/A N/A –2.9 (3.0)
Tate [47] 2001 Basic Internet-based Online program + email reminders 45 98.4 N/A –3.1 (4.4)
Enhanced Internet-based Basic + online behavioral therapy 46 98.5 N/A –6.4 (5.5)
Tate [48] 2003 Basic Internet-based Online program + email reminders 46 111.0 N/A –4.4 (5.7)
Enhanced Internet-based Basic + email counseling 46 108.0 N/A –7.2 (7.5)
van Genugten [49] 2012 Basic Internet-based General information online 239 95.7 93.2 –2.5 (8.6)
Enhanced Internet-based Basic + computer tailored + forum 241 95.9 94.4 –1.5 (9.7)
van Wier [8] 2009 Minimala Brochure 231 101.5 99.5 –2.0 (9.9)
Internet Online program + email counseling 236 102.6 98.6 –1.9 (6.3)
Phone Phone counseling 235 101.5 98.2 –1.2 (11.7)
Webber [50] 2010 Basic Internet-based Online program + message board 36 96.5 N/A –3.6 (5.2)
Enhanced Internet-based Basic + motivational treatment 34 97.3 N/A –3.6 (5.2)
Wijsman [25] 2013 Minimala None 112 101.4 N/A –1.3 (3.6)
Internet Online program + email counseling 114 102.3 N/A –2.3 (3.8)
Yoo [51] 2009 Minimala None 54 91.3 89.1 –2.2 (7.5)
Internet Online monitoring + feedbacks 57 89.5 86.8 –2.7 (9.8)

a Minimal arm includes control, wait-list, usual care groups or the group that only received standard health information.

Of the 72 intervention arms reviewed in the current study, 33 adapted behavioral theories or therapy principles, 40 prompted self-monitoring of behavior, 39 used feedback on performance and individual tailoring or counseling, 31 used goal setting, 15 planned online social support/social change, 6 used motivational interviewing, and 2 used incentives to encourage weight loss. Regarding the total number of components used in each arm, approximately one-third of the arms used none, one-third used 1 to 3 components, and the final one-third used 4 to 6 components. Details about the arm components can be found in Multimedia Appendix 2. A total of 24 pairs were extracted for comparison between Internet-based interventions and minimal interventions. The number of times each component was uniquely found only in Internet-based interventions was 16 for theory, 21 for tailoring, 21 for monitoring, 15 for goal setting, 4 for motivational interviewing, 11 for social support, and 1 for incentive.

Bias assessment showed the following results: 17 studies provided details on random sequence generation, 18 studies provided details on allocation concealment, only 2 studies reported blinding participants, and 9 studies reported blinding assessors. As shown in Multimedia Appendix 3, the bias assessment indicated no evidence of selective reporting of outcomes. As shown in the funnel plot for publication bias (see Multimedia Appendix 4), no significant publication bias was detected (P=.31 for Begg’s test) for Internet-based interventions as evaluated by the waist circumference change in each study arm. Multimedia Appendix 5 shows content and supplementary approaches of substudies included in this meta-analysis.

 Overall Effects of Interventions

Figure 2 shows the differences in waist circumference change between Internet-based interventions and minimal interventions. Internet-based interventions showed significantly better effects on waist circumference reduction (mean change 2.38 cm, 95% CI 1.51-3.25) compared with minimal interventions. Few differences were observed with respect to the waist circumference change between Internet-based interventions and paper-, phone-, or person-based interventions (mean change −0.61 cm, 95% CI −2.05 to 0.83, P=.42). Figure 3 provides a forest plot representing the effect size of Internet-based interventions on the waist circumference change. Overall, Internet-based interventions significantly reduced the waist circumference (mean change −2.99 cm, 95% CI −3.68 to −2.30), whereas minimal interventions (mean change −0.81 cm, 95% CI −1.41 to −0.20) and other interventions (mean −2.82 cm, 95% CI −3.89 to −1.74) also reduced waist circumference. Large and significant between-study heterogeneity was observed (I2=93.3%, P<.001).

Forest plot for the differences in waist circumference changes between Internet-based interventions and minimal interventions. % Weight: weights assigned to substudies.

Forest plot for the effect of Internet-based intervention on waist circumference changes. % Weight: weights assigned to substudies.

 Characteristics Associated With the Waist Circumference Change

The meta-regression of differences in waist circumference changes (changes in minimal intervention groups minus changes in Internet-based intervention groups) showed no significant associations between effect sizes with the content and number of unique intervention components. To further investigate the effect of intervention components, a meta-regression of waist circumference changes from baseline to posttest was conducted. Results of this meta-regression are shown in Table 2. Stepwise meta-regression showed that only the mean waist circumference at baseline (coefficient = −0.16, P<.001) and proportion of male participants (coefficient = −0.02, P=.02) were significantly associated with the effect on waist circumference change (I2=69.8%, P<.001) among the characteristics of the participants that included mean age, reported existing diseases, and status of general obesity. The waist circumference at baseline alone explained 45.3% of the between-study variation in waist circumference changes. Controlling for the baseline waist circumference and proportion of male participants (R 2 =.58), the component of social support in Internet-based intervention was associated with a significantly better effect on waist circumference changes (mean difference −1.16 cm, P=.03), which increased the R 2 to .66.

Meta-regression of waist circumference change from baseline to posttest.a

Intervention component Coefficient SE P I2
Mean waist circumference at baseline (cm) –0.16 0.03 <.001 69.8%
Male participants (%) 0.02 0.01 .02
Length (weeks)b 0.01 0.01 .89 69.9%
Frequency (week per contact)b –0.13 0.20 .54 71.4%
Retention (%)b –0.02 0.01 .15 71.1%
Intervention contentb 70.6%
Physical activity vs both 0.34 0.58 .56
Nutrition vs both –1.38 2.27 .55
Theory (yes vs no)b 0.38 0.53 .48 69.7%
Tailoring (yes vs no)b –0.45 0.58 .45 69.9%
Monitoring (yes vs no)b –0.62 0.66 .35 69.6%
Goal setting (yes vs no) b 0.50 0.57 .38 69.6%
Motivational interviewing (yes vs no) b –0.09 0.77 .91 69.5%
Social support (yes vs no)b –1.16 0.51 .03 66.9%
Number of componentsb –0.12 0.16 .48 69.6%

a The incentive variable was not included in the model because only 1 study used incentives to encourage weight loss.

b Controlled for mean waist circumference at baseline and percentage of male participants.

 Discussion

This study was the first attempt to the authors’ knowledge that evaluated effect sizes of Internet-based lifestyle interventions on decreasing waist circumference. This meta-analysis showed that Internet-based interventions not only decreased waist circumference substantially at posttest (a mean decrease of 2.99 cm), but also did so significantly more than minimal interventions. Given that a meta-analysis of workplace physical activity and dietary behavioral interventions only demonstrated an average waist circumference reduction of 0.67 cm (95% CI −1.96 to 0.63) [52] and another meta-analysis of antiobesity drugs showed an additional waist circumference reduction of 1.72 to 3.58 cm at 3 months among overweight or obese adults compared with standard care groups [53], Internet-based interventions appear to have a promising effect on waist circumference reduction. It deserves mention that this meta-analysis found few differences in waist circumference reduction between Internet-based intervention and paper-, phone-, or person-based lifestyle interventions. Considering that Internet-based interventions can attract a larger number of individuals with various backgrounds [2,4,54], can provide immediate and easy-access support at a lower cost [21,55], are more accessible to older adults and residents of geographically isolated communities [6,11,26], and are less obtrusive [26] than traditional methods, the substantial effect of Internet-based lifestyle interventions on the waist circumference change found in this study adds to the reason that Internet-based rather than traditional lifestyle interventions should be more widely and boldly explored.

Of the 31 trials reviewed in this study, 24 differences between Internet-based intervention and minimal intervention were identified. Compared with minimal interventions, Internet-based interventions included 1 to 6 unique intervention components. In addition, 13 trials tested the differences between basic and enhanced Internet-based interventions. Compared with the basic interventions, the enhanced intervention included 1 or 2 additional intervention features, such as adding healthy diet promotion to physical activity promotion or adding Bluetooth technology to the basic intervention. As indicated in Table 1, some enhanced interventions had a better effect on waist circumference change whereas others had a worse effect than basic interventions. The result of this study indicates that no conclusive evaluation is warranted on the efficacy of such additional features of the Internet-based lifestyle interventions.

To complement findings drawn from current and previous systematic reviews, we tested the associations between key intervention characteristics and waist circumference reduction in meta-regression models where independent variables were selected based on previous findings [9,12,22,27]. We examined whether the content and number of unique intervention components could adequately predict the differences in waist circumference changes between Internet-based interventions and minimal interventions only to find no significant association. The lack of significant association may be explained by lack of power due to the small sample size (n=24). It is also possible that the effect size can be explained by intervention features not tested in the current study. Similar future meta-analysis research is warranted that includes more studies and possibly a different framework. Due, in part, to the concern about the possible insignificant findings arising from low power, another meta-regression was performed for the waist circumference changes from baseline to posttest. We found that only the availability of social support was significantly associated with the waist circumference change after controlling for the main characteristics of participants. This means that providing sufficient social support is important to improve the efficacy of Internet-based lifestyle interventions. The lack of significant associations between waist circumference reduction and intervention length, intervention topic (nutrition only, physical activity only, or both), and the approach used in adjunction to the Internet (eg, personal contacts via phone, in-person visits, or use of such devices as Bluetooth, pedometer, or accelerometer) deserves further research. Although other intervention characteristics did not yield significant results in this review, further investigations are needed to draw conclusive suggestions.

It is worth noting that considerable heterogeneity remained after controlling for baseline waist circumference, gender, and intervention components identified by this study. It indicates that there is heterogeneity in effect sizes among the Internet-based interventions examined in this review that has yet to be accounted for. This may have to do with lack of frameworks that informed the design of Internet-based interventions reviewed in this study or lack of use of well-defined constructs or concepts. Previous studies have found that there is a lack of framework for the design of technology-based behavioral interventions and each research team used their own ways to develop and report technology-based interventions [56,57]. As a result, many of such technology-based intervention features lack comparability between different studies. Eysenbach and colleagues [58] developed the CONSORT-EHEALTH to standardize reports of eHealth/mHealth interventions, which has been very helpful in disseminating and comparing research reports. Recently, Schueller et al [56] proposed the modular system Purple to assist the development of Internet-based and mobile-based applications for health behavior change and Mohr et al [57] proposed a comprehensive framework, the Behavioral Intervention Technology (BIT) Model. These recently proposed frameworks and models should be fully utilized to inform the design of future technology-based interventions. In addition, for comparability and clarity of findings in behavior change interventions, it is desirable to use well-defined terms such as those shown in the Coventry, Aberdeen & London-Refined (CALO-RE) taxonomy [59]. These new frameworks and taxonomy of behavior change techniques will help increase comparability between different technology-based behavioral intervention studies as well as enhance the effectiveness of such interventions.

This meta-analysis review has the following limitations. First, gender-specific analyses were not performed due to a lack of gender-specific information, although baseline waist circumference and changes in the waist circumference may differ by gender. Future studies would be desirable that investigate gender-specific waist circumference changes of Internet-based interventions. Second, paper-, phone-, and person-based interventions were grouped together in this analysis due to a lack of data. Future research can be conducted to compare each mode of lifestyle interventions with other modes of interventions in terms of effect size when the sample size is appropriate. Third, the effect of compliance and incentives were not investigated in this study due to a lack of such information in the reviewed studies. Researchers are recommended to report information on participant compliance and incentives. Finally, considerable heterogeneity in waist circumference changes remained after controlling for covariates including baseline waist circumference and gender. This might indicate that reviewed interventions lacked frameworks that informed their study design. Thus, it is possible that not all the efficacious intervention components in reducing waist circumference for Internet-based lifestyle interventions might have been examined and analyzed.

In summary, Internet-based lifestyle interventions showed a significant and substantial effect on waist circumference change. Internet-based interventions showed comparable effects on the waist circumference change to paper-, phone-, and person-based interventions. Online social support appears to strengthen the effect of Internet-based programs on waist circumference reduction. Internet-based programs are recommended for obesity or lifestyle as effective and efficient interventions. It is also recommended to integrate online social support into Internet-based programs to achieve better effects on weight control.

 Multimedia Appendix 1

Search strategy.

 Multimedia Appendix 2

Components of sub-studies included in this meta-analysis.

 Multimedia Appendix 3

Table for the risk of bias assessment.

 Multimedia Appendix 4

Funnel plot for publication bias.

 Multimedia Appendix 5

Content and supplementary approaches of substudies included in this meta-analysis.

 Abbreviations BIT

Behavioral Intervention Technology

 ERIC

Educational Resource Information Center

 RCT

randomized controlled trial

This work was supported by the National Research Foundation of Korea Grant funded by the Korean Government (NRF-2012S1A3A2033416). The funding agency was not involved with conceptualization, study design, analysis, or drafting of the manuscript.

None declared.

 Swinburn BA Sacks G Hall KD McPherson K Finegood DT Moodie ML Gortmaker SL The global obesity pandemic: shaped by global drivers and local environments Lancet 2011 08 27 378 9793 804 14 10.1016/S0140-6736(11)60813-1 21872749 S0140-6736(11)60813-1 Kodama S Saito K Tanaka S Horikawa C Fujiwara K Hirasawa R Yachi Y Iida KT Shimano H Ohashi Y Yamada N Sone H Effect of Web-based lifestyle modification on weight control: a meta-analysis Int J Obes (Lond) 2012 05 36 5 675 85 10.1038/ijo.2011.121 21694698 ijo2011121 Seo D-C Sa J A meta-analysis of psycho-behavioral obesity interventions among US multiethnic and minority adults Prev Med 2008 12 47 6 573 82 10.1016/j.ypmed.2007.12.010 18201758 S0091-7435(07)00508-7 Neve M Morgan PJ Jones PR Collins CE Effectiveness of web-based interventions in achieving weight loss and weight loss maintenance in overweight and obese adults: a systematic review with meta-analysis Obes Rev 2010 04 11 4 306 21 10.1111/j.1467-789X.2009.00646.x 19754633 OBR646 Norman GJ Zabinski MF Adams MA Rosenberg DE Yaroch AL Atienza AA A review of eHealth interventions for physical activity and dietary behavior change Am J Prev Med 2007 10 33 4 336 345 10.1016/j.amepre.2007.05.007 17888860 S0749-3797(07)00363-7 PMC2180189 Morgan PJ Collins CE Plotnikoff RC Cook AT Berthon B Mitchell S Callister R Efficacy of a workplace-based weight loss program for overweight male shift workers: the Workplace POWER (Preventing Obesity Without Eating like a Rabbit) randomized controlled trial Prev Med 2011 05 52 5 317 25 10.1016/j.ypmed.2011.01.031 21300083 S0091-7435(11)00059-4 Rogers R The Comparison of a Technology-Based System and In-Person Behavioral Weight Loss Intervention in the Severely Obese [dissertation] 2012 Pittsburg, PA University of Pittsburgh van Wier MF Ariëns GA Dekkers JC Hendriksen IJ Smid T van Mechelen W Phone and e-mail counselling are effective for weight management in an overweight working population: a randomized controlled trial BMC Public Health 2009 9 6 10.1186/1471-2458-9-6 19134171 1471-2458-9-6 PMC2667416 Bennett GG Herring SJ Puleo E Stein EK Emmons KM Gillman MW Web-based weight loss in primary care: a randomized controlled trial Obesity (Silver Spring) 2010 02 18 2 308 13 10.1038/oby.2009.242 19696764 oby2009242 PMC3710670 Booth AO Nowson CA Matters H Evaluation of an interactive, Internet-based weight loss program: a pilot study Health Educ Res 2008 06 23 3 371 81 10.1093/her/cyn007 18349032 cyn007 Morgan PJ Lubans DR Collins CE Warren JM Callister R The SHED-IT randomized controlled trial: evaluation of an Internet-based weight-loss program for men Obesity (Silver Spring) 2009 11 17 11 2025 32 10.1038/oby.2009.85 19343018 oby200985 Patrick K Calfas KJ Norman GJ Rosenberg D Zabinski MF Sallis JF Rock CL Dillon LW Outcomes of a 12-month web-based intervention for overweight and obese men Ann Behav Med 2011 12 42 3 391 401 10.1007/s12160-011-9296-7 21822750 Berglund G Ljungman S Hartford M Wilhelmsen L Björntorp P Type of obesity and blood pressure Hypertension 1982 4 5 692 6 7106936 Wang Y Rimm EB Stampfer MJ Willett WC Hu FB Comparison of abdominal adiposity and overall obesity in predicting risk of type 2 diabetes among men Am J Clin Nutr 2005 03 81 3 555 63 15755822 81/3/555 Kamel EG McNeill G Van Wijk MC Change in intra-abdominal adipose tissue volume during weight loss in obese men and women: correlation between magnetic resonance imaging and anthropometric measurements Int J Obes Relat Metab Disord 2000 05 24 5 607 13 10849583 Ross R Rissanen J Hudson R Sensitivity associated with the identification of visceral adipose tissue levels using waist circumference in men and women: effects of weight loss Int J Obes Relat Metab Disord 1996 06 20 6 533 8 8782729 Ross R Janssen I Dawson J Kungl A Kuk JL Wong SL Nguyen-Duy T Lee S Kilpatrick K Hudson R Exercise-induced reduction in obesity and insulin resistance in women: a randomized controlled trial Obes Res 2004 05 12 5 789 98 10.1038/oby.2004.95 15166299 12/5/789 Lee S Kuk JL Davidson LE Hudson R Kilpatrick K Graham TE Ross R Exercise without weight loss is an effective strategy for obesity reduction in obese individuals with and without Type 2 diabetes J Appl Physiol (1985) 2005 09 99 3 1220 5 10.1152/japplphysiol.00053.2005 15860689 00053.2005 Gan SK Kriketos AD Ellis BA Thompson CH Kraegen EW Chisholm DJ Changes in aerobic capacity and visceral fat but not myocyte lipid levels predict increased insulin action after exercise in overweight and obese men Diabetes Care 2003 06 26 6 1706 13 12766098 Vandelanotte C Spathonis KM Eakin EG Owen N Website-delivered physical activity interventions a review of the literature Am J Prev Med 2007 07 33 1 54 64 10.1016/j.amepre.2007.02.041 17572313 S0749-3797(07)00164-X van den Berg MH Schoones JW Vliet Vlieland TP Internet-based physical activity interventions: a systematic review of the literature J Med Internet Res 2007 9 3 e26 10.2196/jmir.9.3.e26 17942388 v9i3e26 PMC2047289 Khaylis A Yiaslas T Bergstrom J Gore-Felton C A review of efficacious technology-based weight-loss interventions: five key components Telemed J E Health 2010 11 16 9 931 8 10.1089/tmj.2010.0065 21091286 PMC3000900 Mehring M Haag M Linde K Wagenpfeil S Frensch F Blome J Schneider A Effects of a general practice guided web-based weight reduction program--results of a cluster-randomized controlled trial BMC Fam Pract 2013 14 76 10.1186/1471-2296-14-76 23981507 1471-2296-14-76 PMC3680299 Miller W Rollnick S Motivational Interviewing, Third Edition: Helping People Change 2012 New York The Guilford Press Wijsman CA Westendorp RG Verhagen EA Catt M Slagboom PE de Craen AJ Broekhuizen K van Mechelen W van Heemst D van der Ouderaa F Mooijaart SP Effects of a web-based intervention on physical activity and metabolism in older adults: randomized controlled trial J Med Internet Res 2013 15 11 e233 10.2196/jmir.2843 24195965 v15i11e233 PMC3841355 Wing R R Jeffery R W Benefits of recruiting participants with friends and increasing social support for weight loss and maintenance J Consult Clin Psychol 1999 02 67 1 132 8 10028217 Seo Dong-Chul Sa Jaesin A meta-analysis of obesity interventions among U.S. minority children J Adolesc Health 2010 04 46 4 309 23 10.1016/j.jadohealth.2009.11.202 20307819 S1054-139X(09)00626-0 Follmann D Elliott P Suh I Cutler J Variance imputation for overviews of clinical trials with continuous response J Clin Epidemiol 1992 07 45 7 769 73 1619456 0895-4356(92)90054-Q Higgins JP Altman DG Gøtzsche PC Jüni P Moher D Oxman AD Savovic J Schulz KF Weeks L Sterne JA Cochrane Bias Methods Group Cochrane Statistical Methods Group The Cochrane Collaboration's tool for assessing risk of bias in randomised trials BMJ 2011 343 d5928 22008217 PMC3196245 Bischoff S The Effects of Goal Setting on Increasing Physical Activity Behavior Through a 16-week Internet-delivered Intervention [master's thesis] 2010 Laramie, WY University of Wyoming Chambliss Heather O Huber Rachel C Finley Carrie E McDoniel Scott O Kitzman-Ulrich Heather Wilkinson William J Computerized self-monitoring and technology-assisted feedback for weight loss with and without an enhanced behavioral component Patient Educ Couns 2011 12 85 3 375 82 10.1016/j.pec.2010.12.024 21295433 S0738-3991(11)00004-8 Bukhari A Effectiveness of a Web-based Nutrition Education Program to Reduce Cardiovascular Disease Risk Among US Army Personnel and Their Families ("Defend Your Heart" study) [dissertation] 2009 Fort Collins, CO Colorado State University Carr Lucas J Bartee R Todd Dorozynski Chris Broomfield James F Smith Marci L Smith Derek T Internet-delivered behavior change program increases physical activity and improves cardiometabolic disease risk factors in sedentary adults: results of a randomized controlled trial Prev Med 2008 05 46 5 431 8 10.1016/j.ypmed.2007.12.005 18207228 S0091-7435(07)00503-8 Chen Yi-Ching Tsao Lee-Ing Huang Chih-Hsung Yu Yi-Yen Liu I-Li Jou Hei-Jen An Internet-based health management platform may effectively reduce the risk factors of metabolic syndrome among career women Taiwan J Obstet Gynecol 2013 06 52 2 215 21 10.1016/j.tjog.2013.04.011 23915854 S1028-4559(13)00067-3 Collins Clare E Morgan Philip J Jones Penelope Fletcher Kate Martin Julia Aguiar Elroy J Lucas Ashlee Neve Melinda J Callister Robin A 12-week commercial web-based weight-loss program for overweight and obese adults: randomized controlled trial comparing basic versus enhanced features J Med Internet Res 2012 14 2 e57 10.2196/jmir.1980 22555246 v14i2e57 PMC3376507 Chung LM Law QP Fong SS Chung JW Teledietetics improves weight reduction by modifying eating behavior: a randomized controlled trial Telemed J E Health 2014 01 20 1 55 62 10.1089/tmj.2013.0104 24205807 PMC3882915 Dekkers JC van Wier MF Ariëns GA Hendriksen IJ Pronk NP Smid T van Mechelen W Comparative effectiveness of lifestyle interventions on cardiovascular risk factors among a Dutch overweight working population: a randomized controlled trial BMC Public Health 2011 11 1 49 10.1186/1471-2458-11-49 21261935 1471-2458-11-49 PMC3037864 Hansen Andreas Wolff Grønbæk Morten Helge Jørn Wulff Severin Maria Curtis Tine Tolstrup Janne Schurmann Effect of a Web-based intervention to promote physical activity and improve health among physically inactive adults: a population-based randomized controlled trial J Med Internet Res 2012 14 5 e145 10.2196/jmir.2109 23111127 v14i5e145 PMC3510714 Herrick M Characterization of Time and Order of Internet Lessons in Project WebHealth [master’s thesis] 2009 Brookings, SD South Dakota State University Hunter CM Peterson AL Alvarez LM Poston WC Brundige AR Haddock CK Van Brunt DL Foreyt JP Weight management using the internet a randomized controlled trial Am J Prev Med 2008 02 34 2 119 26 10.1016/j.amepre.2007.09.026 18201641 S0749-3797(07)00646-0 Kang Ji Yeon Cho Sang Woon Sung Sook Hee Park Yoo Kyoung Paek Yun Mi Choi Tae In Effect of a continuous diabetes lifestyle intervention program on male workers in Korea Diabetes Res Clin Pract 2010 10 90 1 26 33 10.1016/j.diabres.2010.06.006 20621377 S0168-8227(10)00303-7 Mobley A Evaluation of Behavioral Theory and Integrated Internet/telephone Technologies to Support Military Obesity and Weight Management Program [dissertation] 2006 College Park, MD University of Maryland Morgan Philip J Callister Robin Collins Clare E Plotnikoff Ronald C Young Myles D Berry Nina McElduff Patrick Burrows Tracy Aguiar Elroy Saunders Kristen L The SHED-IT community trial: a randomized controlled trial of internet- and paper-based weight loss programs tailored for overweight and obese men Ann Behav Med 2013 04 45 2 139 52 10.1007/s12160-012-9424-z 23129021 Pressler Axel Knebel Uta Esch Sebastian Kölbl Dominik Esefeld Katrin Scherr Johannes Haller Bernhard Schmidt-Trucksäss Arno Krcmar Helmut Halle Martin Leimeister Jan Marco An internet-delivered exercise intervention for workplace health promotion in overweight sedentary employees: a randomized trial Prev Med 2010 51 3-4 234 9 10.1016/j.ypmed.2010.07.008 20638409 S0091-7435(10)00287-2 Pullen Carol H Hageman Patricia A Boeckner Linda Walker Susan Noble Oberdorfer Maureen K Feasibility of Internet-delivered weight loss interventions among rural women ages 50-69 J Geriatr Phys Ther 2008 31 3 105 12 19856616 Seely E Facebook as Social Support for a One-time Weight Loss Intervention Among College Students [Master’s thesis] 2013 Carbondale, IL Southern Illinois University at Carbondale Tate Deborah F Jackvony Elizabeth H Wing Rena R Effects of Internet behavioral counseling on weight loss in adults at risk for type 2 diabetes: a randomized trial JAMA 2003 04 9 289 14 1833 6 10.1001/jama.289.14.1833 12684363 289/14/1833 Tate D F Wing R R Winett R A Using Internet technology to deliver a behavioral weight loss program JAMA 2001 03 7 285 9 1172 7 11231746 joc01569 van Genugten L van Empelen P Boon B Borsboom G Visscher T Oenema A Results from an online computer-tailored weight management intervention for overweight adults: randomized controlled trial J Med Internet Res 2012 14 2 e44 10.2196/jmir.1901 22417813 v14i2e44 PMC3376515 Webber Kelly H Gabriele Jeanne M Tate Deborah F Dignan Mark B The effect of a motivational intervention on weight loss is moderated by level of baseline controlled motivation Int J Behav Nutr Phys Act 2010 7 4 10.1186/1479-5868-7-4 20157441 PMC2821313 Yoo H J Park M S Kim T N Yang S J Cho G J Hwang T G Baik S H Choi D S Park G H Choi K M A Ubiquitous Chronic Disease Care system using cellular phones and the internet Diabet Med 2009 06 26 6 628 35 10.1111/j.1464-5491.2009.02732.x 19538239 DME2732 Verweij LM Coffeng J van Mechelen W Proper KI Meta-analyses of workplace physical activity and dietary behaviour interventions on weight outcomes Obes Rev 2011 06 12 6 406 29 10.1111/j.1467-789X.2010.00765.x 20546142 OBR765 Chilton M Dunkley A Carter P Davies M J Khunti K Gray L J The effect of antiobesity drugs on waist circumference: a mixed treatment comparison Diabetes Obes Metab 2014 03 16 3 237 47 10.1111/dom.12198 23964810 Hamel Lauren M Robbins Lorraine B Wilbur Joellen Computer- and web-based interventions to increase preadolescent and adolescent physical activity: a systematic review J Adv Nurs 2011 02 67 2 251 68 10.1111/j.1365-2648.2010.05493.x 21198800 Hansen Andreas Wolff Grønbæk Morten Helge Jørn Wulff Severin Maria Curtis Tine Tolstrup Janne Schurmann Effect of a Web-based intervention to promote physical activity and improve health among physically inactive adults: a population-based randomized controlled trial J Med Internet Res 2012 14 5 e145 10.2196/jmir.2109 23111127 v14i5e145 PMC3510714 Schueller Stephen M Begale Mark Penedo Frank J Mohr David C Purple: a modular system for developing and deploying behavioral intervention technologies J Med Internet Res 2014 16 7 e181 10.2196/jmir.3376 25079298 v16i7e181 PMC4129186 Mohr David C Schueller Stephen M Montague Enid Burns Michelle Nicole Rashidi Parisa The behavioral intervention technology model: an integrated conceptual and technological framework for eHealth and mHealth interventions J Med Internet Res 2014 16 6 e146 10.2196/jmir.3077 24905070 v16i6e146 PMC4071229 Eysenbach Gunther CONSORT-EHEALTH: implementation of a checklist for authors and editors to improve reporting of web-based and mobile randomized controlled trials Stud Health Technol Inform 2013 192 657 61 23920638 Michie Susan Ashford Stefanie Sniehotta Falko F Dombrowski Stephan U Bishop Alex French David P A refined taxonomy of behaviour change techniques to help people change their physical activity and healthy eating behaviours: the CALO-RE taxonomy Psychol Health 2011 11 26 11 1479 98 10.1080/08870446.2010.540664 21678185 938640058