The effectiveness of a 12 week weight loss challenge on weight loss and physical activity in commercial fitness centres

Abstract

The objective of this study was to examine the effectiveness of a 12 week weight loss intervention in a commercial fitness centre on body mass index (BMI), behavioural regulations consistent with Organismic Integration Theory (OIT, Deci & Ryan, 2002) and moderate to vigorous physical activity (MVPA). Participants were recruited from the general membership to either the intervention (n= 35) or a "do-as-you-do" control (n = 42) group. The intervention group received weekly one-on-one coaching sessions and bi-weekly seminars designed to increase physical activity and improve dietary intake. Pre- and post-intervention all participants received anthropometric assessments and completed self-report instruments to assess behavioural regulations and MVPA. The results of the mixed model analyses of variance showed an increase in MVPA (F = 4.79, p= .03) and a decrease in BMI (F = 8.15, p= .01) in the intervention group when compared to the control across the 12 week intervention. Changes (D) in behavioural regulations were associated with DMVPA congruent with OIT (Deci & Ryan, 2002) regardless of condition. Study results indicate that 12 week weight loss challenges in commercial fitness centres may be effective programming tools in producing short-term anthropometric, behavioural and motivational changes.

Acknowledgments: Support for this research was provided by the Social Sciences and Humanities Research Council of Canada