Mediating Mechanisms of Theory-Based Psychosocial Determinants on Behavioral Changes in a Middle School Obesity Risk Reduction Curriculum Intervention, Choice, Control, and Change

Abstract

Background: A limited number of school-based intervention studies have explored mediating mechanisms of theory-based psychosocial variables on obesity risk behavior changes. The current study investigated how theory-based psychosocial determinants mediated changes in energy balance-related behaviors (EBRBs) among urban youth.

Methods: A secondary analysis study was conducted using data from a cluster randomized controlled trial. Data from students at 10 middle schools in New York City (n = 1136) were used. The intervention, Choice, Control, and Change curriculum, was based on social cognitive and self-determination theories. Theory-based psychosocial determinants (goal intention, cognitive outcome expectations, affective outcome expectations, self-efficacy, perceived barriers, and autonomous motivation) and EBRBs were measured with self-report questionnaires. Mediation mechanisms were examined using structural equation modeling, Results: Mediating mechanisms for daily sugar-sweetened beverage (SSB) consumption and purposeful stair climbing were identified. Models with best fit indices (root mean square error of approximation = 0.039/0.045, normed fit index = 0.916/0.882; comparative fit index = 0.945/0.932; Tucker-Lewis index = 0.896/0.882, respectively) suggested that goal intention and reduced perceived barriers were significant proximal mediators for reducing SSB consumption among both boys and girls or increasing physical activity by stair climbing among boys. Cognitive outcome expectations, affective outcome expectations, self-efficacy, and autonomous motivation indirectly mediated behavioral changes through goal intention or perceived barriers (p < 0.05 to p < 0.001). The final models explained 25%-27% of behavioral outcome variances.

Conclusions: Theory-based psychosocial determinants targeted in Choice, Control, and Change in fact mediated behavior changes in middle school students. Strategies targeting these mediators might benefit future success of behavioral interventions. Further studies are needed to determine other potential mediators of EBRBs in youth.

Figure 1.

Mediation models between psychosocial variables and behavior change in the Choice, Control, and Change curriculum intervention implemented in New York City middle schools. Model (a) is a basic multiple mediator model; Model (b) is the theoretical framework of the Choice, Control, and Change; Model (c) is an alternative social cognitive theory (SCT) and self-determination theory (SDT) mediator model; and Model (d) is another alternative SCT, SDT, and goal intention model.

Figure 2.

The final mediator model for sugar-sweetened beverage (SSB) consumption in the Choice, Control, and Change curriculum. T1 represents pretest and T2 represents post-test scores. Bold arrows and numbers represent significant regression coefficients. e1–e7 are error terms. The unit of daily SSB consumption is ounces (oz). Response options: (a) 1 = will not do it within the next 6 months, 2 = will try within the next 6 months, 3 = plan to do it in a month or so, 4 = currently doing it for past 1–6 months, and 5 = have been doing it for over past 6 months; (b) 1 = strongly disagree, 2 = disagree, 3 = uncertain, 4 = agree, and 5 = strongly agree; and (c) 1 = not sure, 2 = a little sure, 3 = somewhat sure, and 4 = very sure. Scores were coded in a way that higher scores always indicate more desirable for all psychosocial determinants. To enhance clarity of the figure, covariance among T2 variables is not reported. *p < 0.05; ***p < 0.001.

Figure 3.

The final mediator model for purposeful stair climbing activity (STAIR) among boys in the Choice, Control, and Change curriculum. T1 represents pretest and T2 represents post-test scores. Bold arrows and numbers represent significant regression coefficients. e1–e7 are error terms. The unit of daily STAIR is flights: a flight of stairs is going up one floor in a building, such as from the first to the second floor. Response options: (a) 1 = will not do it within the next 6 months, 2 = will try within the next 6 months, 3 = plan to do it in a month or so, 4 = currently doing it for past 1–6 months, and 5 = have been doing it for over past 6 months; (b) 1 = strongly disagree, 2 = disagree, 3 = uncertain, 4 = agree, and 5 = strongly agree; and (c) 1 = not sure, 2 = a little sure, 3 = somewhat sure, and 4 = very sure. Scores were coded in a way that higher scores always indicate more desirable for all psychosocial determinants. To enhance clarity of the figure, covariance among T2 variables is not reported. *p < 0.05; **p < 0.01; ***p < 0.001.