2.1. Study Design
This study was a multiple cohort, staggered-entry, waitlist period controlled clinical trial conducted at three sites in Western Australia (two metropolitan areas and one regional area) [20]. Briefly, overweight adolescents were recruited and assessed three months before the eight-week intensive phase of the intervention commenced, and assessed again immediately prior to the intervention. This method was chosen because it was considered unfair to withhold services from obese adolescents in view of the lack of appropriate treatment services available [21], and the dual pre-participation assessments allowed for a within-subjects control period. The staggered start for the seven cohort groups controlled for external seasonal and public event confounders to intervention effects. Further assessments were completed at the immediate conclusion of the eight-week program and again at three months, six months and 12 months post-intervention [20]. This trial was registered on the Australian New Zealand Clinical Trials Registry (ACTRN12611001187932). Figure 1 shows the progression of participants through the 17 months of the study. Each assessment time point is represented by a box on the left of the figure. In each box, the bold number refers to the number of adolescents potentially still available for each assessment, with the number of drop outs clearly stated on the right of the figure.