Effect of green tea catechins with or without caffeine on anthropometric measures: a systematic review and meta-analysis

Green tea catechins (GTCs) with or without caffeine have been studied in randomized controlled trials (RCTs) for their effect on anthropometric measures and have yielded conflicting results. The objective was to perform a systematic review and meta-analysis of RCTs of GTCs on anthropometric variables, including body mass index (BMI), body weight, waist circumference (WC), and waist-to-hip ratio (WHR). A systematic literature search of MEDLINE, EMBASE, CENTRAL, and the Natural Medicines Comprehensive Database was conducted through April 2009. RCTs that evaluated GTCs with or without caffeine and that reported BMI, body weight, WC, or WHR were included. The weighted mean difference of change from baseline (with 95% CIs) was calculated by using a random-effects model. Fifteen studies (n = 1243 patients) met the inclusion criteria. On meta-analysis, GTCs with caffeine decreased BMI (-0.55; 95% CI: -0.65, -0.40), body weight (-1.38 kg; 95% CI: -1.70, -1.06), and WC (-1.93 cm; 95% CI: -2.82, -1.04) but not WHR compared with caffeine alone. GTC ingestion with caffeine also significantly decreased body weight (-0.44 kg; 95% CI: -0.72, -0.15) when compared with a caffeine-free control. Studies that evaluated GTCs without concomitant caffeine administration did not show benefits on any of the assessed anthropometric endpoints. The administration of GTCs with caffeine is associated with statistically significant reductions in BMI, body weight, and WC; however, the clinical significance of these reductions is modest at best. Current data do not suggest that GTCs alone positively alter anthropometric measurements.