Weight status as a moderator of the relationship between motivation, emotional social support, and physical activity in underserved adolescents.

OBJECTIVE This study examined weight status as a moderator of the relationship between motivation (controlled, autonomous, regulatory), emotional social support (parents, peers) and moderate-to-vigorous physical activity (MVPA) in underserved adolescents (ethnic minority, low-income). METHODS Participants from the Active by Choice Today Trial (n = 1,416; 54% girls, 73% African American, 52% overweight/obese) completed baseline measures, including height and weight, psychosocial surveys, and 7-day accelerometry estimates. Weight status was defined by body mass index z-score (zBMI). RESULTS Weight status moderated the effects of controlled, autonomous, and regulatory motivation on MVPA, such that these variables were more strongly associated with MVPA in adolescents with lower versus higher zBMI scores. CONCLUSIONS A better understanding of why motivation is not related to MVPA in underserved youth with a higher weight status is needed. Future pediatric obesity treatment in underserved youth may need to move beyond motivation into environmental factors associated with long-term behavior change.