Is physical activity a gateway behavior for diet? Findings from a physical activity trial

Objective While cross-sectional research indicates physical inactivity and poor diet tend to co-occur, there are limited longitudinal data on how interventions targeting one behavior affect other behaviors. The current investigation examined cross-sectional and longitudinal relationships between health behaviors within the context of a physical activity (PA) intervention. Methods Sedentary women (n = 280; mean age = 47.1; 94.6% Caucasian) were enrolled in a randomized controlled PA trial comparing the effects of print-based, individually-tailored and gender-targeted PA interventions to a wellness/control condition. Women completed baseline, month 3, and month 12 assessments that included measures of PA and dietary behaviors. Results Participants in more advanced PA stages of change reported significantly greater fruits/vegetables consumption than participants in less advanced stages, although the relationships between diet and minutes of weekly activity were less pronounced. The tailored and targeted print-based PA interventions had no effect on fruit/vegetable intake, although significant reductions in fat intake were observed from baseline (M = 31.24%) to month 3 (M = 30.41%), p < 0.03; and baseline to month 12 (M = 30.36%), p < 0.01. Changes in PA were not predictive of improvements in eating behaviors. Conclusions Although fat intake decreased in the context of this PA intervention, fruit/vegetable intake remained unchanged. Also, PA did not serve as a gateway behavior for dietary improvements. In fact, improvements in activity were associated with increases rather than decreases in fat intake.