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MNT: Weight Management (2015)

Imanaka M, Ando M, Kitamura T, Kawamura T. Effectiveness of web-based self-disclosure peer-to-peer support for weight loss: randomized controlled trial. Journal of Medical Internet Research, 2013; 15: e136. PubMed ID: 23838533
Study Design:
Randomized Controlled Trial
A - Click here for explanation of classification scheme.
Quality Rating:
Neutral NEUTRAL: See Quality Criteria Checklist below.
Research Purpose:
To compare the weight loss between those using the Web-based self-disclosure health support (WSHS) system and those using the email health support (EHS) system. 
Inclusion Criteria:
  • Men and women
  • Age 35 to 65 years
  • BMI of at least 25.0kg/m2.
Exclusion Criteria:
  • Aged less than 35 or over 65 years
  • BMI of less than 24.5kg/m2
  • Receiving dietary and exercise therapies
  • Could not access Internet or email.
Description of Study Protocol:


Participants, who were clients of the Kyoto University Health Service, Japan, were recruited by mail.


  • Baseline characteristics including sex, age, height, weight, waist circumference, target weight loss and quality of life (QOL) were obtained at an initial face-to-face guidance interview conducted by a dietitian
  • Participants were randomly assigned to either the WSHS Group or the EHS Group, using the minimization method and were assigned a dietitian
  • After 12 weeks, participants were asked to come in for follow-up and remeasurement of height, weight, waist circumference and QOL by the same dietitian that conducted the initial face-to-face interview. 


  • WSHS Group
    • Participants in the WSHS Group could freely access the WSHS system
    • Participants set their target body weight at the beginning and were requested to enter their present body weight, lifestyle modifications attained (such as food records and exercise) and motivation level [expressed using a three-level scale (good, fair, poor)] on a private web page every week
    • Through this web-based system, they received nutritional advice and had their intakes calculated by their assigned dietitians and they could send questions to their dietitians
    • Group members could also view their fellow participants’ weight changes (not actual values) and health status.
  • EHS Group
    • Participants in the EHS Group were provided with a Microsoft Excel file which they used to document their target body weight at the beginning and, subsequently, their present body weight, lifestyle modifications attained and motivation level on a weekly basis
    • They could send questions to and receive nutritional advice and intake calculations from their assigned dietitians by email, however they could not obtain information about the other group members’ health status.

Statistical Analysis

  • Based on 0.9 power to detect a significant difference (P=0.05, two-sided), 85 participants were required for each study group
  • Intent-to-treat analysis was conducted
  • Baseline characteristics were compared between groups using unpaired Student T-test for numerical variables and Pearson chi-square test for categorical variables
  • Analysis of covariance was used to evaluate the inter-group comparison of the changes before and after intervention, adjusting for sex, age and baseline value of the corresponding item at the first guidance interview
  • All tests were two-tailed and P-values of less than 0.05 were considered statistically significant.
Data Collection Summary:

Timing of Measurements

Measurements were obtained at baseline and at 12-week follow-up.

Dependent Variables

  • Primary outcome: Body weight
  • Secondary outcomes: BMI, waist circumference and quality of life (QOL).

Independent Variables

WSHS or EHS for 12 weeks.

Control Variables

Sex, age and baseline values were used as covariates.

Description of Actual Data Sample:
  • Initial N: 193 (166 male, 27 female)
  • Attrition (final N): 175 (87 in the WSHS Group; 88 in the EHS Group)
  • Age: 50±7 years
  • Ethnicity: Not described
  • Other relevant demographics: Not described
  • Anthropometrics: There were no differences in sex ratio, BMI, waist circumference, target body weight loss or QOL levels between groups
  • Location: Japan.
Summary of Results:

Key Findings

  • Weight loss was significantly greater in the WSHS Group than in the EHS Group (-1.6kg vs. -0.7kg; adjusted P=0.04)
  • The decrease in BMI tended to be greater in the WSHS Group than in the EHS Group, although it was not statistically significant (-0.6 vs. -0.3; adjusted P=0.05)
  • There were no significantly different changes in waist circumference
  • Changes in QOL scores, general health perception, vitality, role functioning related to physical and emotional problems and mental health were not significantly different between groups. 
Author Conclusion:
  • The newly developed WSHS system using forced self-disclosure had better short-term weight loss results
  • Further study in a longer-term trial is necessary to determine what effects this type of intervention might have on long-term cardiovascular disease.
Funding Source:
University/Hospital: Kyoto University School of Public Health
Reviewer Comments:
  • Reported limitations
    • WSHS was limited to those who can use a personal computer
    • There was only an observed effect on weight loss. The true end-point should be a reduction in mortality and morbidity from cardiovascular diseases.
    • There was a lack of information on the number of interactions over the web interface over the study period and the dietitian interaction with each participant; differences might influence the difference in weight loss among participants
    • There was a lack of information on the social influence on participants’ behaviors, which might also affect change of weight loss
    • Short observation period of the study; obesity requires long-term solutions.
  • A total of 13 dietitians provided nutrition counseling under the direction of a principal dietitian. Each dietitian was allocated to both a WSHS Group and a EHS Group to minimize inter-group differences in dietitians’ counseling. Each dietitian uniformly counseled the participants based on a standardized manual to maintain homogeneity of guidance among dietitians.
  • It is not known whether participants could see questions or comments from other participants and dietitians.
Quality Criteria Checklist: Primary Research
Relevance Questions
  1. Would implementing the studied intervention or procedure (if found successful) result in improved outcomes for the patients/clients/population group? (Not Applicable for some epidemiological studies) Yes
  2. Did the authors study an outcome (dependent variable) or topic that the patients/clients/population group would care about? Yes
  3. Is the focus of the intervention or procedure (independent variable) or topic of study a common issue of concern to dieteticspractice? Yes
  4. Is the intervention or procedure feasible? (NA for some epidemiological studies) Yes
Validity Questions
1. Was the research question clearly stated? Yes
  1.1. Was (were) the specific intervention(s) or procedure(s) [independent variable(s)] identified? Yes
  1.2. Was (were) the outcome(s) [dependent variable(s)] clearly indicated? Yes
  1.3. Were the target population and setting specified? Yes
2. Was the selection of study subjects/patients free from bias? Yes
  2.1. Were inclusion/exclusion criteria specified (e.g., risk, point in disease progression, diagnostic or prognosis criteria), and with sufficient detail and without omitting criteria critical to the study? Yes
  2.2. Were criteria applied equally to all study groups? Yes
  2.3. Were health, demographics, and other characteristics of subjects described? Yes
  2.4. Were the subjects/patients a representative sample of the relevant population? Yes
3. Were study groups comparable? Yes
  3.1. Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT) Yes
  3.2. Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline? Yes
  3.3. Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.) Yes
  3.4. If cohort study or cross-sectional study, were groups comparable on important confounding factors and/or were preexisting differences accounted for by using appropriate adjustments in statistical analysis? N/A
  3.5. If case control study, were potential confounding factors comparable for cases and controls? (If case series or trial with subjects serving as own control, this criterion is not applicable.) N/A
  3.6. If diagnostic test, was there an independent blind comparison with an appropriate reference standard (e.g., "gold standard")? N/A
4. Was method of handling withdrawals described? Yes
  4.1. Were follow-up methods described and the same for all groups? Yes
  4.2. Was the number, characteristics of withdrawals (i.e., dropouts, lost to follow up, attrition rate) and/or response rate (cross-sectional studies) described for each group? (Follow up goal for a strong study is 80%.) Yes
  4.3. Were all enrolled subjects/patients (in the original sample) accounted for? Yes
  4.4. Were reasons for withdrawals similar across groups? Yes
  4.5. If diagnostic test, was decision to perform reference test not dependent on results of test under study? N/A
5. Was blinding used to prevent introduction of bias? Yes
  5.1. In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate? Yes
  5.2. Were data collectors blinded for outcomes assessment? (If outcome is measured using an objective test, such as a lab value, this criterion is assumed to be met.) Yes
  5.3. In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded? N/A
  5.4. In case control study, was case definition explicit and case ascertainment not influenced by exposure status? N/A
  5.5. In diagnostic study, were test results blinded to patient history and other test results? Yes
6. Were intervention/therapeutic regimens/exposure factor or procedure and any comparison(s) described in detail? Were interveningfactors described? No
  6.1. In RCT or other intervention trial, were protocols described for all regimens studied? Yes
  6.2. In observational study, were interventions, study settings, and clinicians/provider described? N/A
  6.3. Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect? No
  6.4. Was the amount of exposure and, if relevant, subject/patient compliance measured? No
  6.5. Were co-interventions (e.g., ancillary treatments, other therapies) described? N/A
  6.6. Were extra or unplanned treatments described? N/A
  6.7. Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups? N/A
  6.8. In diagnostic study, were details of test administration and replication sufficient? N/A
7. Were outcomes clearly defined and the measurements valid and reliable? Yes
  7.1. Were primary and secondary endpoints described and relevant to the question? Yes
  7.2. Were nutrition measures appropriate to question and outcomes of concern? Yes
  7.3. Was the period of follow-up long enough for important outcome(s) to occur? Yes
  7.4. Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures? Yes
  7.5. Was the measurement of effect at an appropriate level of precision? Yes
  7.6. Were other factors accounted for (measured) that could affect outcomes? Yes
  7.7. Were the measurements conducted consistently across groups? Yes
8. Was the statistical analysis appropriate for the study design and type of outcome indicators? Yes
  8.1. Were statistical analyses adequately described and the results reported appropriately? Yes
  8.2. Were correct statistical tests used and assumptions of test not violated? Yes
  8.3. Were statistics reported with levels of significance and/or confidence intervals? Yes
  8.4. Was "intent to treat" analysis of outcomes done (and as appropriate, was there an analysis of outcomes for those maximally exposed or a dose-response analysis)? Yes
  8.5. Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)? Yes
  8.6. Was clinical significance as well as statistical significance reported? Yes
  8.7. If negative findings, was a power calculation reported to address type 2 error? N/A
9. Are conclusions supported by results with biases and limitations taken into consideration? Yes
  9.1. Is there a discussion of findings? Yes
  9.2. Are biases and study limitations identified and discussed? Yes
10. Is bias due to study's funding or sponsorship unlikely? Yes
  10.1. Were sources of funding and investigators' affiliations described? Yes
  10.2. Was the study free from apparent conflict of interest? Yes