Green tea for weight loss and weight maintenance in overweight or obese adults.
Level 1 - systematic review of randomized trials
Systematic review and meta-analysis of randomized controlled trials
PubMed 23235664 · doi:10.1002/14651858.CD008650.pub2
What was done
This Cochrane systematic review searched 10 major databases up to January 2012 for randomized controlled trials (RCTs) lasting at least 12 weeks that evaluated green tea preparations versus control for weight loss or weight maintenance in overweight or obese adults. Study quality and risk of bias were independently assessed by three authors. Because of high heterogeneity, studies were analyzed separately based on trial location (conducted in Japan versus outside Japan).
What was found
Study durations ranged from 12 to 13 weeks. For trials conducted outside Japan, meta-analyses showed no significant effect on weight loss (6 RCTs, n=532; MD -0.04 kg, 95% CI -0.5 to 0.4; P = 0.88), BMI (n=222; MD -0.2 kg/m², 95% CI -0.5 to 0.1; P = 0.21), waist circumference (5 RCTs, n=404; MD -0.2 cm, 95% CI -1.4 to 0.9; P = 0.70), or waist-to-hip ratio (3 RCTs, n=144; MD 0.0, 95% CI -0.02 to 0.01). In 8 Japanese trials (n=1,030), marked heterogeneity prevented pooling; individual study results favored green tea, with weight loss differences ranging from -0.2 kg to -3.5 kg, BMI reductions ranging from 0 to -1.3 kg/m², and waist circumference changes ranging from +1 cm to -3.3 cm. Two weight maintenance studies (n=184) showed weight changes between +0.6 kg and -1.6 kg. Reported adverse events were primarily mild to moderate.
Why it matters
Green tea preparations do not induce a clinically meaningful or statistically robust weight loss or weight maintenance effect in overweight or obese adults.
Limits
Follow-up was short across all included trials (12–13 weeks). High heterogeneity among Japanese trials precluded pooled quantitative analysis. Many trials had small sample sizes, and none reported on patient satisfaction, morbidity, or cost-effectiveness.
Cited by
- supports Fat burner supplements and stimulants do not significantly aid in fat loss through their direct mechanisms alone, but rather through acute effects like increased motivation, training output, and occasional appetite suppression.