Challenging body weight: evidence from a community-based intervention on weight, behaviour and motivation.

The objective of this study was to examine the effectiveness of a 12 week weight loss intervention within a commercial fitness centre on body weight, moderate to vigorous physical activity (MVPA), dietary intake, and behavioural regulations for exercise and healthy eating. Using a quasi-experimental design, the intervention group received weekly coaching sessions and bi-weekly seminars designed to increase MVPA and improve dietary intake. Outcome variables were assessed at three time points over a six month period. Results showed a significant interaction for body weight (p = .04) and dietary changes (p < .05) following the weight loss challenge but were not maintained across the six month period. Changes in behavioural regulations favoured the intervention condition. Results imply that a 12 week weight loss challenge within a commercial fitness centre may be effective at prompting short-term weight loss and support the internalization of behavioural regulations specific to healthy eating and exercise.