Purpose: This presentation will describe the process of development of the NOHoW trial logic models, emphasizing the theoretical frameworks that are represented in these models.The logic models were used as the basis for the content and features of the NoHoW digital Toolkit (TK)

Purpose: Preventing weight regain for 12 months is a difficult challenge. Behavior change theories suggest that motivation and behavior regulation skills contribute to behavior change maintenance, resulting in sustained weight management. We hypothesized that fostering one's basic psychological needs and autonomous motivation can lead to increased and better use of behavior regulation skills such as planning, which, in turn, will promote more stable behavior changes and weight changes.

The present study is a secondary analysis of the NoHoW trial. Its main goal is to test if a mediational model, resulting from the integration of self-determination theory and behavioral regulation approaches, could explain body weight change (primary outcome of the NoHoW trial).

Methods: The NoHoW is a three-center, large scale weight regain prevention trial. Adults who lost > 5% of their weight in the past year (N=870, 68.7% female, 44.10±11.86 years, 84.47±17.03 kg) participated in a 12-months digital behavior change based intervention. Weight and validated measures of motivational and self-regulatory skills' related variables were collected at baseline, six- and 12-months. Change variables were used in Mplus' mediation model analysis, according to NoHoW's logic model (data from study arms was pooled).

Results: The bivariate correlation analysis confirmed key mediators' potential effect on weight outcomes in the expected causal direction. The main analysis shows that about a quarter of the variance (r2=23.5%) of weight regain prevention is achieved via the mechanisms of action predicted in the logic model. Specifically, our analysis points out the role of a need for supportive climate care, improvements in needs satisfaction and goal contents leading to better weight regain prevention via improvements in self-regulatory skills, i.e., action control, coping, and action planning, in addition to increases in exercise controlled motivation.

Conclusions: These results contribute to a better understanding of behavior change maintenance in the context of weight regain prevention. While developing a digital behavior change intervention, researchers and practitioners should consider a need for supportive climate care, with content aiming at improving needs satisfaction and intrinsic goal contents.

Purpose: Behavioural interventions promoting physical activity (PA) are a promising approach to prevent weight regain. However, evidence about efficacy is still limited. There is a need to test mechanisms of action of theory-based digital behaviour change interventions focusing on PA promotion. The current study is a secondary analysis of the NoHoW trial and investigated the theory-based mechanisms of action that promote long-term PA outcomes. The NoHoW trial is a theory-based digital intervention with a 2x2 factorial design 18-month randomized controlled trial to promote weight loss maintenance through PA and eating behaviour regulation.

Methods: A subsample of 855 weight losers (M Age = 45.69 ± 11.37; 67.1% female) completed all questionnaires on target antecedent variable and mediators and had all objectively measured PA data available for 0, 6 and 12 months. We examined the direct and the indirect effects of Virtual Care Climate (autonomy support of intervention) on PA changes(6 to 12 months) through changes in the motivational and self-regulatory mediators (0 to 6 months), as conceptualized in the theory-based logic model. 

Results: Model 1 tested the mediation processes on Steps and presented a poor fit to the data. Model 2 tested mediation processes on sedentary behaviour and PA intensity levels and presented reasonable fit to the data (𝝌2/df = 8.12, p = 0.001; CFI = .959; RMSEA = .091). Specific indirect effects showed that treatment care climate was positively and indirectly associated with self-regulatory skills via two distinct paths: i) intrinsic goals and autonomous motivation, and ii) BPN satisfaction and autonomous motivation. In turn, autonomous motivation was positively and indirectly associated with increases in the number of steps, moderate and vigorous intensity PA via action control. Only Action Control operated to directly predict long-term PA. 

Conclusions: We found specific indirect effects on increases in PA via motivational and self-regulatory mechanisms. Post intervention changes in PA and in sedentary behaviour (12 months) were predicted by the logic model. Motivational and self-regulatory psychological mechanisms tested may represent possible targets for future interventions focusing on the promotion of long-term PA in adults trying to maintain their weight loss.