Ultra-processed food and the risk of overweight and obesity: a systematic review and meta-analysis of observational studies

Background Numerous studies have reported the association of ultra-processed foods with excess body weight; however, the nature and extent of this relation has not been clearly established. This systematic review was conducted to analyze the currently documented evidence regarding the association between ultra-processed food with overweight and obesity. Methods A literature search was performed using multiple literature databases for relevant articles published prior to November 2019. Random effects model, namely the DerSimonian-Laird method, was applied to pool effect sizes. The potential sources of heterogeneity across studies were explored using the Cochrane Q test. Results Fourteen studies (one cohort study and thirteen cross-sectional studies) were included in this review. A significant association was identified between ultra-processed food intake and overweight (pooled effect size: 1.02; 95% confidence interval (95% CI): 1.01, 1.03,p < 0.001) and obesity (pooled effect size: 1.26; 95% CI: 1.13, 1.41,p < 0.001). Conclusion Our findings revealed a positive association between ultra-processed foods and excess body weight. Future studies with longitudinal designs and adequate control for confounding factors are required to clarify whether ultra-processed food intake alters anthropometric parameters and leads to obesity.