An 8-week web-based weight loss challenge with celebrity endorsement and enhanced social support: observational study.

BACKGROUND: 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.

OBJECTIVE: 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.

METHODS: 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.

RESULTS: Using GLMM, including weight data for all participants, there was significantly greater (P=.03) 8-week weight loss in SC (-5.1 kg [-5.5 to -4.6 kg] or -6.0%) compared to BLC participants (-4.5 kg [-4.8, -4.2] or -5.0%). Dropout rates were low and consistent across groups (BLC: 17 (1.8%) vs SC: 2 (0.5%), P=.08) and 48.7% (456/936) of BLC and 51.2% (184/379) of SC participants accessed the website at 8 weeks, with no difference between programs (P=.48). SC participants accessed the discussion forums, menu plans, exercise plans, and educational materials significantly more than BLC participants (P<.05).

CONCLUSIONS: 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.