Understanding determinants for weight-loss is a national priority. Obesity is an epidemic with serious health consequences. Most of today’s obesity and overweight problems are being attributed to poor diets and not enough physical activity. These problems show no signs of slowing down with the behaviors of most Americans. The phenomenon of “The Biggest Loser” (different variants of weight-loss programs that consist of group exercise participation and nutrition therapy to elicit weight-loss, and hopefully behavior change) has spawned many variants in commercial health clubs. This prospectus study examined the direct and interactive or moderated effects of known determinants of healthy behaviors. Those determinants were conscientiousness and perceived autonomy support. Thus, the purpose of this prospective study was to examine these two determinants of adhering to a variant of “The Biggest Loser” to gain more scientific knowledge of predictors of those that are successful in such commercial programs.


Participants were 64 adults who completed measures of conscientiousness and perceived autonomy support along with a number of other measures being taken such as weight, attendance, and relative autonomy for exercise prior to and during the 12-week Weight-loss program. Participants’ attendance was kept based on showing up to the five scheduled weight and body fat percentage measurements time points during the 12-week program. At final weigh-in, the participants completed the measure of perceived autonomy support from their group exercise leader.


Overall, conscientiousness appeared to be the most influential variable in the prospective study. It correlated with relative autonomy (r=.26, M=11.36, SD=6.43), perceived leader autonomy support (r=.08, M=5.32, SD=1.58, α=.97), attendance (r=.14, M=3.84, SD=1.31), and change in weight (r=-.09, M=-15.26, SD=29.06).Results from the moderated regression analyses, one set for attendance and the other for change in weight, suggested that conscientiousness was the major determinant in this prospective study though admitted the correlations were small in magnitude.


As hypothesized, the interaction of autonomy support (high) and conscientiousness (high) yielded the greatest amount of weight loss. Thus, for the sample in this prospective study, best results were found in highly conscientiousness participants that perceived their group exercise leader to provide a great deal of autonomy support. Future, studies should investigate environmental factors to increase both participant conscientiousness (e.g., reminder phone calls) and leader provided autonomy support.



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