Background: New Zealand Pacific and Māori populations measure disproportionately high on the international body mass index (BMI). Information is needed on what behavioural weight loss goals to recommend and how to attract and retain them in interventions. Our team weight loss competition trial for participants with a BMI ≥30 used cash prizes to incentivise completion of nine daily behaviour goals. This paper evaluates the theoretical merit of and adherence to these goals.
Methods: A qualitative component evaluation methodology was used. Trial data on team activity, demographics and anthropometric outcome data were extracted to determine frequency of daily goal completion by teams throughout the competition and to describe participant characteristics. T-tests were used to compare completion rates of the challenges, challenge completion by day of week and between weekdays and weekends. To examine adherence to the daily challenge activity over 24 weeks the total amount of completed challenges adjusted for number of active teams was plotted by week. A Body Shape Index (ABSI) was used to determine individual anthropometric change from baseline to 8, 16 and 24 weeks. Program documents were analysed to identify barriers to adherence and retention of participants.
Results: Of 19 teams (N = 130) who began only five teams performed daily goals across the whole 24 weeks. Adherence was highest during the first 8 weeks. No difference in performance between goals was found suggesting they were equally viable, though tasks worth less points were performed more frequently. Goal completion was higher on weekdays. The behaviour goals appeared to have theoretical merit in that more members of high performing teams experienced a positive change in their ABSI.
Conclusions: Incentives offer a promising strategy for encouraging retention in weight loss interventions. This study suggests that participants in a competition will perform incentivised tasks. The findings however, are limited by missing data and high drop out of individuals and whole teams. Further research is needed on how to increase retention.
Keywords: Indigenous; Lifestyle challenges; Obesity prevention; Weight loss competition.