The Effectiveness of Combined Dietary and Physical Activity Interventions for Improving Dietary Behaviors, Physical Activity, and Adiposity Outcomes in Adolescents Globally: A Systematic Review and Meta-Analysis

This systematic review and meta-analysis examined the effectiveness of combined diet and physical activity interventions on changes in dietary and physical activity behaviors, and adiposity related outcomes in adolescents globally. PubMed, Embase, and Cochrane were searched for controlled interventions targeting dietary behaviors and physical activity in adolescents aged 10-19 years at baseline and reporting on the outcomes of changes in dietary and physical activity behaviors. Behavioral outcomes were synthesized narratively, and meta-analyses were conducted for changes in adiposity related outcomes (e.g., BMI z-scores, body fat percentage). Thirty-six studies were included, most (79%) were conducted in high-income countries and delivered in school settings (n = 28, 78%). Ten interventions (28%) showed no effect on any behaviors, and 5 (14%) reported changing all behaviors targeted and assessed. Most (72%) interventions changed at least one of the behaviors assessed, and 39% changed one or more indicator of adiposity. In a subsample (k = 16), there was a nonsignificant reduction in BMI (SMD -0.11 [95% CI -0.26 to 0.04]; I2 = 90%), a significant moderate reduction in BMI z-score (k = 14) (SMD -0.62 [-1.09 to -0.16]; I2 = 99%), and in body fat percentage in favor of the intervention groups (k = 11) (SMD -1.32 [-2.22 to -0.42]; I2 = 99%). The evidence for interventions targeting both dietary and physical activity behaviors and their effect on behavior and adiposity in adolescents is largely inconsistent. The positive findings from few studies suggests that there is potential to improve some lifestyle behaviors and associated adiposity outcomes in adolescents. However, the current evidence is focussed on high income countries with little consideration given to potential inequities in the effects of interventions.