Minimal research sheds light on L-theanine’s potential to suppress weight gain.
The amino acid L-theanine is one of the major bioactive ingredients in green tea. It has been suggested to potentially aid fat loss by:
- Regulating fat accumulation. Theanine has been shown to suppress weight gain and fat accumulation in animals.
Theanine is an amino acid found in plants and fungi in a variety of forms, the most common of which is L-theanine. Its structural similarity to the neurotransmitters glutamine and glutamate seems to be responsible for a number of nootropic effects:
L-theanine has been growing in popularity since its discovery as one of the main components of green tea (Camilla sinensis).1 Indeed, L-theanine is the main ingredient responsible for the feeling of calm focus frequently associated with tea consumption. Theanine has also been purported to stabilize blood pressure, boost immune function during exercise, and possibly even promote weight loss.2
How L-Theanine Might Help With Fat Loss
Regulating fat digestion and absorption
Although the precise mechanism is unknown, theanine has been reported to help manage weight in animals.4 Moreover, as one of the principal active ingredients in green tea, it’s possible that it is partially responsible for green tea’s fat loss bio-activities, including limiting digestion and absorption of fat, enhancing metabolism, and lowering levels of free fatty acids and glucose, both of which are linked to obesity.5 6
L-Theanine Benefits & Uses for Fat Loss
Using theanine supplements for promoting weight loss is a relatively new development, and one that is currently only backed by a few animal studies. Having said that, theanine supplementation is popular for a number of uses that may help facilitate a healthy weight, namely: 7
- Enhancing mood, focus and overall cognitive function
- Reducing anxiety
- Making it easier to fall asleep and improving sleep quality
- Combating cardiovascular complications
Animal research has suggests that theanine may be capable of suppressing weight gain and help with obesity.
In this study, female mice were fed a variety of diets containing 2% green tea powder or 0.3% catechins, 0.05% caffeine, and 0.03% theanine (individually and in combination) for 16 weeks. Theanine (both separately and with the other compounds) was found to limit body weight increase and the amount of adipose tissue (stored fat) in the body, as well as reduce levels of triglycerides (TG) and fatty acids in the blood.
- The study concluded that “caffeine and theanine were responsible for the suppressive effect of green tea powder (GTP) on body weight increase and fat accumulation. Moreover, it was shown that catechins and caffeine were synergistic in anti-obesity activities.”8
In this study, mice were fed a normal diet, a high-fat diet (HFD), HFD with green tea (GT) containing high levels of theanine, or HFD with catechins. At the end of the investigation, the HFD with GT diet was shown to mitigate the fat accumulating consequences of obesity induced by the HFD. In other words, theanine-rich green tea had anti-obesity effects.
- The study concluded that “obese mice showed changes associated with abnormal lipid and energy metabolism, which were alleviated by GT intake, indicating the mechanism underlying the anti-obesity effects of GT.”9
There are currently no clinical studies directly examining the impact of isolated theanine on fat loss. As a critical ingredient in green tea’s composition, however, theanine may plausibly be found to promote fat-burning activities in future studies. (See clinical research backing green tea as a fat burner).
Dosage for Fat Loss
- Research studies generally use from 200 – 400 mg of L-theanine
- Typical supplements come in 50 – 100 mg capsules, taken 1 – 4 times daily
Supplements in Review Says
- L-theanine as Suntheanine® 200 mg for fat loss.
There is far too little research to recommend L-theanine for weight loss. Theanine may very well be a natural weight loss agent due to its association with green tea, but no human studies have demonstrated any such effect as of yet. However, animal research does suggest a possible weight loss effect, so you can certainly give L-theanine a try.
Best way to take theanine is as Suntheanine. Suntheanine is currently the only form of L-theanine clinically proven to be safe and effective.
- Cooper R. Green tea and theanine: health benefits. Int J Food Sci Nutr. 2012 Mar;63 Suppl 1:90-7. ↩
- Murakami S, Kurihara S, et al. Effects of oral supplementation with cystine and theanine on the immune function of athletes in endurance exercise: randomized, double-blind, placebo-controlled trial. Biosci Biotechnol Biochem. 2009 Apr 23;73(4):817-21 ↩
- Mu W, Zhang T. An overview of biological production of L-theanine. Biotechnol Adv. 2015 May-Aug;33(3-4):335-42. ↩
- Vuong QC, Bowyer MC, et al. L-Theanine: properties, synthesis and isolation from tea. J Sci Food Agric. 2011 Aug 30;91(11):1931-9. ↩
- Juhel C, et al. Green tea extract (AR25) inhibits lipolysis of triglycerides in gastric and duodenal medium in vitro. J Nutr Biochem. 2000 Jan;11(1):45-51. ↩
- Wolfram S, et al. Anti-obesity effects of green tea: From bedside to bench. Mol Nutr Food Res. 2006, 50, 176-87. ↩
- Turkozu D, Sanlier L. L-theanine, unique amino acid of tea, and its metabolism, health effects, and safety. Crit Rev Food Sci Nutr. 2017 May 24;57(8):1681-7. ↩
- Zheng G, Sayama K, et al. Anti-obesity effects of three major components of green tea, catechins, caffeine and theanine, in mice. In Vivo. 2004 Jan-Feb;18(1):55-62. ↩
- Lee LS, Choi JH, et al. Green tea changes serum and liver metabolomic profiles in mice with high-fat diet-induced obesity. Mol Nutr Food Res. 2015 Apr;59(4):784-94. ↩
- Murakami S, Kurihara S, et al. Kinetics of L-theanine uptake and metabolism in healthy participants are comparable after ingestion of L-theanine via capsules and green tea. Biosci Biotechnol Biochem. 2009 Apr 23;73(4):817-21. ↩