The Effects of Physical Activity and Diet Interventions on Body Mass Index in Latin American Children and Adolescents: A Systematic Review and Meta-Analysis

The objective of this systematic review and meta-analysis is to compare the effect of physical activity only with that of physical activity plus diet interventions on body mass index (BMI) in Latin American children and adolescents. We searched the Medline, Embase, Scopus, Web of Science, and Scielo databases from their inception until March 2020, including studies examining the effect of physical activity or physical activity plus diet interventions on BMI in children and adolescents and based on data from intervention studies. The DerSimonian and Laird method was used to compute a pooled standardized mean difference for BMI in terms of effect size (ES) and respective 95% confidence intervals (CIs). Eighteen studies were included. Analyses were performed based on intervention (four studies were included for physical activity only and four studies were included for physical activity plus diet). In the analysis of physical activity only versus control, there was no effect on BMI (ES = 0.00; 95% CI -0.17-0.17, I-2 = 0.0%; p = 0.443). In the analysis of physical activity plus diet versus control, there was a decrease in BMI in favour of the intervention group (ES = -0.28; 95% CI -0.42--0.14, I-2 = 74.5%; p = 0.001). When ES was estimated considering only the effect in intervention groups, there was no evidence of a decrease in BMI (ES = -0.17; 95% CI -0.44-0.11, I-2 = 84.5%; p < 0.001) for physical activity only (eight studies). However, there was a statistically significant decrease in BMI (ES = -0.30; 95% CI -0.50-0.11, I-2 = 95.8%; p < 0.001) for physical activity plus diet (ten studies). Some limitations of this review could compromise our results, but the main limitation that should be stated is the quality of the studies (mainly medium/moderate), especially as physical activity and diet interventions cannot be blinded, compromising the quality of these studies. In summary, this meta-analysis offers evidence that physical activity plus diet interventions produced a reduction in BMI in Latin American children and adolescents, but physical activity only interventions did not.