title: [Effect of green tea or green tea extract consumption on body weight and body composition; systematic review and meta-analysis].
abstract: BACKGROUND
  Caffeine and catechins contained in green tea may have a thermogenic effect favoring weight and body fat loss. The aim of this study is to evaluate the magnitude of the effect of green tea or its extracts (caffeine and catechins) on body weight and body composition.
  
  
  METHODS
  A systematic review and meta-analysis was conducted to determine the magnitude of the effect of green tea or its extracts on body weight (kg), body mass index (BMI) (kg/m2), fat mass (%), and waist and hip circumference (cm). We included studies published between 2000 and 2013, retrieved from PubMed/Medline with the following characteristics: randomized controlled trials (RCTs) of parallel groups (intervention and placebo), randomized, double-blind, and a minimum 12-week follow-up, in healthy individuals of either gender, 18 years or older, with a BMI of 25-40 kg/m2. Quality and risk of bias was assessed for every included study, and the statistical analysis was performed with the Crochrane Collaboration RevMan 5.1.6 software, according to the random effects model with a confidence interval of 95% (95%). It was established that the effect was statistically significant at p < 0.05, and the homogeneity of the studies was assessed using the I2 index.
  
  
  RESULTS
  The search strategy retrieved 154 studies, of which only five could be included in the quantitative analysis. The analysis revealed a not statistically significant mean difference (MD) in weight loss in the analyzed sample and subgroups: Asian individuals -0.81 kg (95% CI: -2.76 to 1.13; P = 0.41; I2 = 0%, n = 210), Caucasians -0.73 kg (95% CI: -3.22 to 1.75; P = 0.45; I2 = 0%; n = 91), as well as in the sample as a whole: -0.78 kg (95% CI: -2.31 to 0.75; P = 0.32; I2 = 0%; n = 301). No statistically significant decrease was revealed in BMI in the analyzed sample and subgroups: Asian individuals -0.65 (95% CI: -1.85 to 0.54; P = 0.29; I2 = 0%; n = 71), -0.21 Caucasians (95% CI: -0.96 to 0.53; P = 0.58; I2 = 22%; n = 91), as well as in the sample as a whole: -0.31 kg (95% CI: -0.88 to 0.27; P = 0.30; I2 = 0%; n = 162), nor for the waist circumference 0.08 cm (95% CI: -0.39 to 0.55; P = 0.73; I2 = 3%; n = 301) or hip (95% CI: -1.14 to 0.93; P = 0.85; I2 = 0%; n = 210). In the evaluation of the effect on the percentage of fat mass (FM%), MD was found not statistically significant for population subgroups: Asian individuals -0.76 (95% CI: -1.59 to 0.08; P = 0.08; I2 = 0%; n = 169), Caucasians -0.76 (95% CI: -2.22 to 0.70; P = 0.31; I2 = 36%; n = 93), but a small, although statistically significant, decrease in the overall effect was found -0.76 (95% CI: -1.44 to -0.09; P = 0.03; I2 = 0%; n = 260).
  
  
  CONCLUSIONS
  The statistically significant effect of green tea on the FM% of the entire sample was not clinically relevant, a fact also highlighted in the results of other meta-analysis. CONCLUSION OF THE AUTHORS: Green tea or gree tea extracts intake or its extracts exerts no statistically significant effect on the weight of overweight or obese adults. There is a small effect on the decrease in the percentage of fat mass, but it is not clinically relevant.
authors.affiliation: Grupo de Revisión, Estudio y Posicionamiento. Asociación Española de Dietistas-Nutricionistas (GREP-AEDN). Barcelona. España.. info@grep-aedn.es.
authors.forename: Eduard
authors.initials: E
authors.lastname: Baladia
authors.affiliation: Grupo de Revisión, Estudio y Posicionamiento. Asociación Española de Dietistas-Nutricionistas (GREP-AEDN). Barcelona. España.. info@grep-aedn.es.
authors.forename: Julio
authors.initials: J
authors.lastname: Basulto
authors.affiliation: Grupo de Revisión, Estudio y Posicionamiento. Asociación Española de Dietistas-Nutricionistas (GREP-AEDN). Barcelona. España.. info@grep-aedn.es.
authors.forename: María
authors.initials: M
authors.lastname: Manera
authors.affiliation: Grupo de Revisión, Estudio y Posicionamiento. Asociación Española de Dietistas-Nutricionistas (GREP-AEDN). Barcelona. España.. info@grep-aedn.es.
authors.forename: Rodrigo
authors.initials: R
authors.lastname: Martínez
authors.affiliation: Consultor Estadístico Independiente. Investigación Estadística. España.. info@grep-aedn.es.
authors.forename: David
authors.initials: D
authors.lastname: Calbet
mesh_terms: D001823:Body Composition / Q000187:drug effects*; D001835:Body Weight / Q000187:drug effects*; D006801:Humans; D009765:Obesity / Q000188:drug therapy; D050177:Overweight / Q000188:drug therapy; D010936:Plant Extracts / Q000494:pharmacology* / Q000627:therapeutic use; D013662:Tea
chemical_list: D010936:Plant Extracts; D013662:Tea
vernacular_title: Efecto del consumo de té verde o extractos de té verde en el peso y en la composición corporal; revisión sistemática y metaanálisis.