Is there a relationship between red or processed meat intake and obesity? A systematic review and meta-analysis of observational studies.

A body of literature exists regarding the association of red and processed meats with obesity; however, the nature and extent of this relation has not been clearly established. The aim of this study is to conduct a systematic review and meta-analysis of the relationship between red and processed meat intake and obesity. We searched multiple electronic databases for observational studies on the relationship between red and processed meat intake and obesity published until July 2013. Odds ratios (ORs) and means for obesity-related indices and for variables that may contribute to heterogeneity were calculated. A systematic review and a meta-analysis were conducted with 21 and 18 studies, respectively (n = 1,135,661). The meta-analysis (n = 113,477) showed that consumption of higher quantities of red and processed meats was a risk factor for obesity (OR: 1.37; 95% CI: 1.14-1.64). Pooled mean body mass index (BMI) and waist circumference (WC) trends showed that in comparison to those in the lowest ntile, subjects in the highest ntile of red and processed meat consumption had higher BMI (mean difference: 1.37; 95% CI: 0.90-1.84 for red meat; mean difference: 1.32; 95% CI: 0.64-2.00 for processed meat) and WC (mean difference: 2.79; 95% CI: 1.86-3.70 for red meat; mean difference: 2.77; 95% CI: 1.87-2.66 for processed meat). The current analysis revealed that red and processed meat intake is directly associated with risk of obesity, and higher BMI and WC. However, the heterogeneity among studies is significant. These findings suggest a decrease in red and processed meat intake.