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Initial engagement and weight loss within Web-based weight loss programs may predict long-term success. The integration of persuasive Web-based features may boost engagement and therefore weight loss.
To determine whether an 8-week challenge within a commercial Web-based weight loss program influenced weight loss, website use, and attrition in the short term, when compared to the standard program.
De-identified data for participants (mean age 36.7±10.3 years; 86% female) who enrolled in the Biggest Loser Club (BLC) (n=952) and the BLC’s Shannan Ponton Fast Track Challenge (SC) for 8 weeks (n=381) were compared. The BLC program used standard evidence-based website features, with individualized calorie and exercise targets to facilitate a weight loss of 0.5-1 kg per week (–500kcal/day less than estimated energy expenditure). SC used the same website features but in addition promoted greater initial weight loss using a 1200 kcal/day energy intake target and physical activity energy expenditure of 600 kcal/day. SC used persuasive features to facilitate greater user engagement, including offering additional opportunities for social support (eg, webinar meetings with a celebrity personal trainer and social networking) endorsed by a celebrity personal trainer. Self-reported weekly weight records were used to determine weight change after 8 weeks. A primary analysis was undertaken using a generalized linear mixed model (GLMM) with all available weight records for all participants included. Dropout (participants who cancelled their subscription) and nonusage (participants who stopped using the Web-based features) attrition rates at 8 weeks were calculated. The number of participants who accessed each website feature and the total number of days each feature was used were calculated. The difference between attrition rates and website use for the two programs were tested using chi-square and Wilcoxon Rank Sum tests, respectively.
Using GLMM, including weight data for all participants, there was significantly greater (
Using a short-term challenge with persuasive features, including online social support with endorsement by a celebrity personal trainer, as well as a greater energy balance deficit, within a commercial Web-based weight loss program may facilitate greater initial weight loss and engagement with some program components. The results support the need for a more rigorous and prospective evaluation of Web-based weight loss programs that incorporate additional strategies to enhance initial weight loss and engagement, such as a short-term challenge.
Recent systematic reviews suggest Web-based interventions facilitate modest weight loss [
Web-based weight loss program providers are therefore exploring new ways to improve initial program success. This includes the use of persuasive technology [
Therefore, the aim of this observational study was to determine whether an 8-week “challenge” version of a commercial Web-based weight loss program influenced weight loss, website use, and attrition in the short term, when compared to the standard commercial Web-based weight loss program. The 8-week challenge provided enhanced system credibility support through the use of a celebrity personal trainer to endorse the program and host additional opportunities for social support.
Participants were adults aged 18-74 years with a body mass index (BMI) >18.5kg/m2 who subscribed to the standard Web-based weight loss program for at least the minimum subscription length of 12 weeks from June 27, 2011, to October 24, 2011, or the 8-week “challenge” version of the program, which began October 24, 2011. The subscription must have been the participants’ first for the commercial program, and those who did not pay for their subscription (eg, free promotional program trials) were excluded. The cost of a subscription in 2011 was AU$149 for SC. For BLC, the cost ranged from AU$19.95 per month if paid upfront for 12 months to AU$49.95 per month if paid monthly.
The commercial Web-based weight loss program was managed by SP Health Co, Australia. The standard program was The Biggest Loser Club (BLC) [
Description of the key components of the Biggest Loser Club (BLC) and Shannan Challenge (SC) programs linked to Persuasive Systems Design 4 categories.
Component | BLC | SC |
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Individualized calorie targets based on participants’ estimated total energy expenditure at enrollment based on their reported height, weight, and activity level and their desire to lose weight (–500kcal/day less than estimated expenditure) or maintain their weight [Primary Task Support]. | Calorie target is 1200 calories for all participants. The exercise plan is 6 days/wk with aim to burn 600 calories/day [Primary Task Support]. |
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Food and physical activity diaries to monitor calorie targets and search engines to facilitate entry of food data [Primary Task Support]. | As per BLC |
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Monitoring of reported body weight, waist and hip girths; graphical display of changes in data and body (BMI) silhouette. Participants were encouraged to “weigh in” once/wk [Primary Task & Dialogue Support]. | As per BLC plus weight loss leader board with a prize for member who achieves the greatest percentage weight loss each week [Primary Task, Dialogue & Social Support]. |
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Daily and weekly calculations of energy balance and meeting recommended nutrient and food group targets from online diary [Dialogue Support]. | As per BLC |
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Automated (computer-generated) weekly personalized feedback on their dietary intake and exercise based on their diary entries, as well as their use or lack of use of the standard website features, and the level of success of their weight loss [Dialogue Support]. | As per BLC |
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Weekly menu plan and grocery list [Primary Task Support]. | As per BLC |
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Weekly physical activity plan [Primary Task Support]. | As per BLC plus choice of a Home or Gym exercise program including video demonstrations from a celebrity personal trainer “Shannan” [System Credibility Support]. |
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Weekly tutorials, fact sheets, and challenges, which participants are prompted to access via a weekly email [Primary Task Support]. | As per BLC |
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Discussion forum [Social Support] | Exclusive discussion forum where only Challenge members can post comments [Social Support]. |
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Historical online meetings hosted by an accredited practicing dietitian could be viewed by BLC participants [Social Support]. | Weekly video blog with personal trainer “Shannan” [Social & System Credibility Support]. |
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Participants received weekly reminders to weigh in via email or SMS [Dialogue Support]. | As per BLC |
SP Health Co collected the data that were provided to the researchers in a de-identified form. Ethics approval for the study was obtained from the University of Newcastle Human Research Ethics Committee, NSW, Australia.
Participants’ pretreatment demographic (sex, age, and ethnicity) and anthropometric characteristics (weight and height) were captured from an enrollment survey. Participants’ self-reported height and weight were used to calculate BMI (weight in kilograms divided by height in meters squared), which was categorized as healthy (BMI 18.5-24.9 kg/m2), overweight (BMI 25-29.9 kg/m2), or obese (BMI ≥30 kg/m2).
Participants self-reported weights (in kilograms) recorded online weekly were used to determine weight change achieved after 8 weeks. Two types of attrition rates were calculated: dropout and nonusage [
Data analysis was undertaken using Stata 11.0 (StataCorp). Basic descriptive statistics were used to describe the baseline characteristics and website usage data. Differences between the two programs were tested using chi-square test for categorical data,
Overall the study included 1334 individuals (953 BLC, 381 SC). Participants were predominantly female (86%), with an average age of 36.7±10.3 years, and half were of Anglo-Saxon descent (
In total, 19 participants (1.4%) dropped out during the 8-week period with no significant difference in dropout rates between the two programs, but a possible trend of higher dropout rates among BLC participants: BLC 17 (1.8%) vs SC 2 (0.5%),
The primary analysis using GLMM resulted in a mean self-reported weight reduction of −4.6 kg (95% CI −4.9 to −4.4 kg) or −5.3% for all participants. SC participants self-reported significantly greater weight loss (–5.1 kg [–5.5 to –4.6 kg] or –6.0%) than BLC participants (–4.5kg [–4.8, –4.2] or –5.0%) after 8 weeks (
The sensitivity analysis using LOCF gave a mean self-reported weight loss of −2.7 kg (−2.9 to −2.6 kg) or −3.0% after 8 weeks for all participants. SC participants self-reported significantly greater weight loss (–3.0 kg [–3.3 to –2.6kg] or –3.4%) than BLC participants (–2.6 kg [–2.9 to –2.4 kg] or –2.9%) after 8 weeks (
Website use for SC and BLC participants is described in
Baseline characteristics of participants who enrolled in the BLC or the SC programs.
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Total (n=1334) | BLC (n=953) | SC (n=381) |
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Female | 85.9 (1146) | 85.2 (812) | 87.7 (334) | .22 |
Age in yrs, mean (SD) |
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36.7 (10.3) | 36.5 (10.7) | 37.1 (9.1) | .35 |
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Anglo-Saxon | 51.0 (680) | 49.5 (472) | 54.6 (208) | .55 |
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Other | 18.8 (251) | 19.9 (189) | 16.3 (62) |
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Did not wish to respond | 30.2 (403) | 30.6 (292) | 29.1 (111) |
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32.3 (7.0) | 33.0 (7.1) | 30.6 (6.5) | <.001 |
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Normal weight % (n) | 12.4 (166) | 10.3 (98) | 17.9 (68) | <.001 |
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Overweight % (n) | 31.8 (424) | 29.1 (277) | 38.6 (147) |
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Obese % (n) | 55.8 (744) | 60.7 (578) | 43.6 (166) |
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Weight change after 8 weeks for BLC and SC participants using GLMM and LOCF (all analyses controlled for baseline age and gender).
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Mean (95% CI) | Effect size, |
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Total (n=1334) | BLC (n=953) | SC (n=381) | Difference between groups |
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Absolute (kg) | -4.6 (-4.9, -4.4) | -4.5 (-4.8, -4.2) | -5.1 (-5.5, -4.6) | -0.6 (-1.2, -0.6) | 0.06 | .03 |
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Percentage (%) | -5.3 (-5.4, -5.1) | -5.0 (-5.2. -4.7) | -6.0 (-6.4, -5.7) | -1.1 (-1.5, -0.7) | 0.14 | <.001 |
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Absolute (kg) | -2.7 (-2.9, -2.6) | -2.6 (-2.9, -2.4) | -3.0 (-3.3, -2.6) | -0.3 (-0.5, -0.2) | 0.09 | .005 |
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Percentage (%) | -3.0 (-3.2, -2.8) | -2.9 (-3.1, -2.6) | -3.4 (-3.7, -3.0) | -0.5 (-0.7, -0.4) | 0.15 | <.001 |
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Weight gain, % (n) | 3.9 (52) | 4.7 (45) | 1.8 (7) | N/A | N/A | .02 |
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0% to <5%, % (n) | 72.1 (962) | 72.6 (692) | 70.9 (270) |
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5% to <10%, % (n) | 20.8 (278) | 20.0 (191) | 22.8 (87) |
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10% or more % (n) | 3.2 (42) | 2.6 (25) | 4.5 (17) |
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Website use by BLC and SC participants from enrollment to 8 weeks.
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BLC (n=953) | SC (n=381) |
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Percentage used, |
Frequencya
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Percentage used, |
Frequencya
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Percentage usedb
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Frequencyc |
Weekly weigh-in | 97.8 (932) | 5 (2-8) | 97.6 (372) | 5 (2-8) | .86 | .83 |
Online diary—food | 86.3 (822) | 11 (3-28) | 80.6 (307) | 8 (1-25) | .009 | .006 |
Online diary—exercise | 77.7 (740) | 4 (1-11) | 73.2 (279) | 5 (0-14) | .09 | .46 |
Discussion forum posts | 39.9 (380) | 0 (0-2) | 73.8 (281) | 5 (0-22) | <.001 | <.001 |
Discussion forum views | 19.6 (187) | 0 (0-0) | 55.4 (211) | 1 (0-8) | <.001 | <.001 |
Accessed menu plan | 91.0 (867) | 3 (1-9) | 96.3 (367) | 8 (3-15) | <.001 | <.001 |
Accessed physical activity plan | 84.2 (802) | 2 (1-4) | 94.8 (361) | 6 (3-11) | <.001 | <.001 |
Accessed weekly educational tips and challenges | 88.9 (847) | 2 (1-5) | 93.4 (356) | 5 (2-8) | .01 | <.001 |
Attended weekly online meeting (webinar) | N/A | N/A | 57.0 (217) | 1 (0-2) | N/A | N/A |
aFrequency is the number of days the feature was used.
bDifference between the two programs tested using chi-square test.
cDifference between the two programs tested using Wilcoxon Rank Sum test.
The primary aim of this study was to determine whether an 8-week challenge version of a commercial Web-based weight loss program, which integrated persuasive features including system credibility support through the use of a celebrity personal trainer to endorse the program and host additional opportunities for social support, demonstrated greater initial weight loss and program engagement compared to the standard program. In the current study, the 8-week challenge version facilitated greater weight loss and engagement, but dropout and nonusage attrition rates were comparable to the standard program.
The true weight loss achieved by participants is likely to be in the range between the GLMM and LOCF results, that is, -3.4% to -6.0% for the SC and -2.9% to -5.0% for BLC, due to reasons previously described [
The differences in initial weight loss and engagement between the BLC and SC programs could be partly explained by the inclusion of additional persuasive features. By offering more opportunities for social support to SC participants, a more supportive environment may have been created [
The weight loss analysis used participants’ weigh-in records self-reported online. However, the accuracy of weight self-reported on the Internet has been shown to be reasonable [
This preliminary observational study supports the need for further evaluation of Web-based weight loss programs that incorporate persuasive strategies, including enhanced credibility support and social support, to enhance initial weight loss and engagement. Future randomized control trials accompanied by mediation analyses should specifically determine which intervention components (ie, persuasive features: social support and/or celebrity endorsement, or stringent eating and physical activity recommendations) of the Web-based program are associated with improvements in engagement and weight loss, and whether initial weight loss and engagement are maintained in the long term.
Online food and exercise diary used by SC and BLC participants.
Weekly self-monitoring of weight for BLC and SC.
Additional opportunity for social support for SC participants: Facebook page.
Additional opportunity for social support for SC participants: Weekly online meeting.
Biggest Loser Club
body mass index
Generalized Linear Mixed Model
last observation carried forward
Shannan Ponton Fast Track Challenge
We acknowledge the work of Grant Kwok in retrieving the data and Anna Crook from SP Health for assistance with managing the dataset. CEC is supported by a National Health and Medical Research Council Australian Career Development Research Fellowship.
CEC has been a nutrition consultant to SP Health Co and MJH received a PhD scholarship supplement from SP Health Co and partial fellowship from the Penn Foundation. All other authors declare that they have no competing interests.