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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.
This study aimed to systematically review the effect of Internet-based interventions on waist circumference change among adults.
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.
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.
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.
The prevalence of obesity has been increasing worldwide for approximately 50 years and has now become a global pandemic [
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) [
Previous reviews have reported that Internet-based interventions can promote physical activity and significantly reduce body weight [
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
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.
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 [
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
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.
Flow chart of literature search.
This review includes 31 intervention trials involving 72 intervention arms and 8442 adults [
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 [ |
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 [ |
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 [ |
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 [ |
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 [ |
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 [ |
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 [ |
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 [ |
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 [ |
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 [ |
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 [ |
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 [ |
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 [ |
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 [ |
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 [ |
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 [ |
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 [ |
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 [ |
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 [ |
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 [ |
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 [ |
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 [ |
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 [ |
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 [ |
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 [ |
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 [ |
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 [ |
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 [ |
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 [ |
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 [ |
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 [ |
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
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
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.
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
Meta-regression of waist circumference change from baseline to posttest.a
Intervention component | Coefficient | SE |
|
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.
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) [
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
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 [
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 [
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.
Search strategy.
Components of sub-studies included in this meta-analysis.
Table for the risk of bias assessment.
Funnel plot for publication bias.
Content and supplementary approaches of substudies included in this meta-analysis.
Behavioral Intervention Technology
Educational Resource Information Center
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.