Identifying momentary predictors of physical activity intentions and behavior among behavioral weight loss participants.

Abstract

Background: Many participants in behavioral weight loss (BWL) programs struggle to meet the moderate-to-vigorous physical activity (MVPA) prescription. Elucidating momentary predictors of MVPA in BWL programs could improve targeting of risk/protective factors, which may boost MVPA adherence and enhance weight control; yet this remains unstudied.

Purpose: To examine momentary factors as potential predictors of MVPA intentions, behavior, and the intention-behavior gap among BWL participants.

Methods: Participants (N = 116) were adults with overweight/obesity in a 12-week remote BWL intervention that prescribed 150 minutes of MVPA/week. Participants wore Fitbits (measuring MVPA) and received 6 daily ecological momentary assessments (EMA; brief, smartphone-delivered surveys) for 2-week periods at treatment initiation, mid-treatment, and end-of-treatment. EMA measured MVPA intention and 11 potential predictors of MVPA intentions/behaviors (based on empirical support from non-BWL contexts). Multilevel models tested within-person relations between predictors and MVPA outcomes, controlling for survey number per day, weekday/weekend status, and assessment period.

Results: Stress, tiredness, and pain/discomfort negatively predicted MVPA intention, whereas energy, positive affect, a positive social interaction, self-control, self-efficacy, and self-compassion positively predicted MVPA intention. Tiredness negatively predicted MVPA behavior, whereas energy, positive affect, self-control, body satisfaction, and self-efficacy positively predicted MVPA. Tiredness also predicted increased odds of an intention-behavior gap.

Conclusions: This study identified 9 momentary predictors of MVPA intentions, 6 predictors of MVPA engagement, and 1 predictor of the MVPA intention-behavior gap in a BWL program. These findings identify potential intervention targets, and momentary digital interventions may try to modify or provide support around these factors in real-time to facilitate MVPA.