OBJECTIVE: To explore participation, consistency of demographic and health profiles, and short-term impacts across six Aboriginal Knockout Health Challenge (KHC) team-based weight loss competitions, 2012 to 2015. METHODS: Data comprised one competition each from 2012 and 2013 and two per year in 2014 and 2015. We compared baseline and change (pre- to post-competition) in weight, fruit and vegetable consumption, physical activity and waist circumference (baseline only) across competitions using mixed models. RESULTS: Numbers of teams and participants increased from 2012 to 2015 from 13 and 324 to 33 and 830, respectively. A total of 3,625 participants registered, representing 2,645 unique people (25.4% repeat participation). Participants were mainly female and >90% were classified obese at baseline. Baseline weight and weight lost (between 1.9% and 2.5%) were significantly lower in subsequent competitions compared with the first. Improvements in fruit and vegetable consumption and physical activity were comparable across competitions. CONCLUSION: The KHC has increasing and sustained appeal among Aboriginal communities, attracting those at risk from lifestyle-associated chronic disease and effectively reducing weight and promoting healthy lifestyles in the short term. Implications for public health: Community-led programs generated by, and responsive to, Aboriginal Australians' needs can demonstrate consistent community reach and sustained program-level lifestyle improvements
