Green tea weight loss is a hot topic in scientific research labs around the world. Scientists often obfuscate the meaning of their research. Does green tea work for weight loss or not? Here are some comments from scientific journals.
Survey of Green Tea Weight Loss Articles
A search in the PubMed medical database yields 83 articles from ‘green tea AND weight loss’. Many of these are only tangentially related to weight loss, or not related at all. Most have to do with biochemical indicators or with laboratory animals. The few that entailed human subjects and weight loss are listed here.
These are the 13 articles most germane to the topic of green tea weight loss in human subjects. Some are original research studies with new data and some are summary articles. Each reference below includes the journal citation, the title of the article, a list of the authors, and a selected comment that summarizes the main results regarding weight loss in that article (quoted in italics).
1. Br J Nutr. 2011 Nov;106(9):1297-309. Epub 2011 Aug 3.
The putative effects of green tea on body fat: an evaluation of the evidence and a review of the potential mechanisms.
An evaluation of the available evidence supports a role of green tea in weight loss; however the extent of the effects obtained is still subject to debate, and requires more objective quantification in future research.
2. J Nutr Biochem. 2011 Jan;22(1):1-7. Epub 2010 Nov 5.
Antiobesity effects of green tea catechins: a mechanistic review.
Rains TM, Agarwal S, Maki KC.
Results from a number of randomized, controlled intervention trials have shown that consumption of GTC (270 mg to 1200 mg/day) may reduce body weight and fat.
The predominating hypothesis is that GTC influences sympathetic nervous system (SNS) activity, increasing energy expenditure and promoting the oxidation of fat.
3. J Hum Nutr Diet. 2010 Dec;23(6):590-600. doi: 10.1111/j.1365-277X.2010.01078.x. Epub 2010 Aug 27.
Green tea improves metabolic biomarkers, not weight or body composition: a pilot study in overweight breast cancer survivors.
Stendell-Hollis NR, Thomson CA, Thompson PA, Bea JW, Cussler EC, Hakim IA.
Intake of decaffeinated green tea for 6 months was associated with a slight reduction in body weight and improved HDL and glucose homeostasis in overweight breast cancer survivors.
4. Am J Clin Nutr. 2010 Jan;91(1):73-81. Epub 2009 Nov 11.
Effect of green tea catechins with or without caffeine on anthropometric measures: a systematic review and meta-analysis.
Phung OJ, Baker WL, Matthews LJ, Lanosa M, Thorne A, Coleman CI.
The administration of GTCs [green tea catechins] with caffeine is associated with statistically significant reductions in BMI, body weight, and WC [waist circumference]; however, the clinical significance of these reductions is modest at best.
5. Int J Obes (Lond). 2009 Sep;33(9):956-61. Epub 2009 Jul 14.
The effects of green tea on weight loss and weight maintenance: a meta-analysis.
Hursel R, Viechtbauer W, Westerterp-Plantenga MS.
Catechins or an epigallocatechin gallate (EGCG)-caffeine mixture have a small positive effect on WL [weight loss] and WM [weight management].
6. Altern Med Rev. 2009 Jun;14(2):154-60.
Greenselect Phytosome as an adjunct to a low-calorie diet for treatment of obesity: a clinical trial.
Di Pierro F, Menghi AB, Barreca A, Lucarelli M, Calandrelli A.
After 90 days of treatment, significant weight loss and decreased body mass index (BMI) were observed in the group taking the herbal extract (14-kg loss in the green tea group compared to a 5-kg loss in the diet-only group); waistline was reduced only in male subjects.
7. Rev Salud Publica (Bogota). 2008 Nov-Dec;10(5):818-30.
A systematic review of the effectiveness of alternative weight-loss products’ ingredients. [Article in Spanish]
de Lira-García C, Souto-Gallardo M, Bacardí-Gascón M, Jiménez-Cruz A.
Only two studies (green tea and Garcinia cambogia) showed significant weight-loss (25%) amongst control and experimental groups.
8. Am J Clin Nutr. 2009 Mar;89(3):822-30. Epub 2009 Jan 28.
Green tea catechin plus caffeine supplementation to a high-protein diet has no additional effect on body weight maintenance after weight loss.
Hursel R, Westerterp-Plantenga MS.
The green tea-caffeine mixture, as well as the HP [high protein] diet, improved WM [weight management] independently through thermogenesis, fat oxidation, sparing FFM [fat-free mass], and, for the HP diet, satiety; a possible synergistic effect failed to appear.
9. J Nutr. 2009 Feb;139(2):264-70. Epub 2008 Dec 11.
Green tea catechin consumption enhances exercise-induced abdominal fat loss in overweight and obese adults.
Maki KC, Reeves MS, Farmer M, Yasunaga K, Matsuo N, Katsuragi Y, Komikado M, Tokimitsu I, Wilder D, Jones F, Blumberg JB, Cartwright Y.
These findings suggest that green tea catechin consumption enhances exercise-induced changes in abdominal fat and serum TG [triglycerides].
10. Clin Nutr. 2008 Jun;27(3):363-70. Epub 2008 May 12.
Effect of green tea extract on obese women: a randomized, double-blind, placebo-controlled clinical trial.
Hsu CH, Tsai TH, Kao YH, Hwang KC, Tseng TY, Chou P.
This study showed no statistical difference in % reduction in BW [body weight], BMI and WC [waist circumference] between the GTE [green tea extract] and placebo groups after 12 weeks of treatment. The intake of GTE (491 mg catechins containing 302 mg EGCG) for 12 weeks is considered safe as shown by the results.
11. Physiol Behav. 2008 Feb 27;93(3):486-91. Epub 2007 Oct 18.
Effectiveness of green tea on weight reduction in obese Thais: A randomized, controlled trial.
Auvichayapat P, Prapochanung M, Tunkamnerdthai O, Sripanidkulchai BO, Auvichayapat N, Thinkhamrop B, Kunhasura S, Wongpratoom S, Sinawat S, Hongprapas P.
We conclude that green tea can reduce body weight in obese Thai subjects by increasing energy expenditure and fat oxidation.
12. J Am Coll Nutr. 2007 Aug;26(4):389S-395S.
The effects of epigallocatechin-3-gallate on thermogenesis and fat oxidation in obese men: a pilot study.
Boschmann M, Thielecke F.
These findings suggest that EGCG alone has the potential to increase fat oxidation in men and may thereby contribute to the anti-obesity effects of green tea.
13. Obes Res. 2005 Jul;13(7):1195-204.
Body weight loss and weight maintenance in relation to habitual caffeine intake and green tea supplementation.
Westerterp-Plantenga MS, Lejeune MP, Kovacs EM.
High caffeine intake was associated with weight loss through thermogenesis and fat oxidation and with suppressed leptin in women. In habitual low caffeine consumers, the green tea-caffeine mixture improved WM, partly through thermogenesis and fat oxidation.
Most articles indicate a positive outcome regarding supplementation with green tea extracts (NOT green tea itself and NOT green tea encapsulated whole leaf powder). The trend is clear, although you may notice that scientists almost never agree on the answers to simple questions about weight loss. Indeed, the article in reference 10 contradicts the positive results in the other articles.
In reading through the articles themselves, which is a bit tedious, I find that one of the main issues is whether the active ingredients – EGCG and its brethren catechins – are absorbed. This issue was addressed directly in reference 6. It is a topic all by itself, which I will review soon in a separate post.
Updating green tea weight loss research,