If you’re familiar with L-theanine, odds are you first learned about this compound strictly in the context of enhancing cognitive performance.

Or maybe you heard that L-theanine can help you get better sleep.

In either case, L-theanine is typically presented solely as a cognitive compound—one you take to either relax or calmly sharpen your focus, especially in conjunction with the focus-enhancing effects of caffeine.

But, as an amino sourced from Camellia sinensis (green tea leaves), L-theanine also seems to possess significant weight management advantages, just like green tea in toto.

Surprisingly, despite its narrow reputation as a cognitive enhancer, L-theanine may also be beneficial for cutting excess body fat and improving your relationship to your diet for greater overall weight control.

While the primary benefits of L-theanine predominantly occur within the central nervous system (CNS), the indirect health and fitness effects of L-theanine’s neural activity may pose significant advantages for the athletes and exercisers looking to procure a leaner, more cut physique.

But to understand how L-theanine achieves so much, we need to first understand exactly what this nootropic amino acid is all about. So, let’s start here with the basics: What exactly is L-theanine?

What is L-Theanine?

Simply put, L-theanine is an amino acid found in the leaves of the Camellia sinensis plant, which is used for most teas: green, white, black, and so on. As a bioactive constituent of Camellia sinensis, L-theanine is largely responsible for the calming, relaxing effects of, say, a hot cup of green tea.

This is why green tea, despite having caffeine, is perceived as “relaxing,” as opposed to a cup of coffee, which has caffeine but no L-theanine.

L-theanine’s structural similarities to the neurotransmitters glutamine and glutamate seem to be responsible for this non-proteinogenic amino’s nootropic benefits.1 In a standard 200 mg cup of black tea, an estimated 24mg L-theanine can be expected—compared to 8 mg L-theanine per 200 mg green tea.2 

However, to fully experience the nootropic benefits (and fat loss benefits, as we’ll get into shortly) of L-theanine, it’s advised to take an L-theanine supplement upwards of 100+ mg per serving.

List of the Nootropic Benefits of L-Theanine

Uniquely, L-theanine seems to calm cognition without sedating it. And, yet, despite not sedating cognition, L-theanine also seems to assist with sleep quality.

L-theanine is believed to serve such contradictory nootropic benefits not by flushing your brain with excess “artificial” neurochemical activity, as many smart drug cognitive enhancers do, but rather through enhancing alpha brainwave frequencies across your brain activity.3

Associated with calm, creative, meditative thinking, alpha brainwaves put you in a sort of cognitive “flow state”—like you’re “in the zone”—totally calm and composed yet focused on the task at hand.

The primary nootropic benefits of L-theanine include:

  • Improved focus and attention
  • Reduced stress and anxiety
  • Enhanced sleep quality
  • Increased mood and motivation
  • Better memory and task-related cognition

And, yes, in addition to boosting cognition, L-theanine may also assist with fat loss.

L-Theanine for Weight Loss: Does It Work?

It’s fairly well-known that green tea extract, with its rich concentration of antioxidant catechins (most notably epigallocatechins-3-gallate, or EGCG), offers significant health and fitness advantages, including cardiometabolic and weight management benefits.4

However, L-theanine, as a constituent of green tea, fails to get similar recognition as a weight-loss compound. Perhaps because, to be fair, catechins have possibly a greater impact on weight regulation than standalone L-theanine.

All the same, L-theanine, especially in conjunction with a potent green tea extract, does seem to work for fat loss.

While the catechin content of green tea gets all the attention when it comes to fat loss, L-theanine may be partially responsible for green tea’s weight loss benefits.

L-Theanine Benefits for Weight Loss

Certainly, through the interplay between psychological state and physical energy output, L-theanine may serve significant fat-burning advantages related to exercise.

However, the nootropic compound also seems to possess more direct weight loss benefits that don’t totally overlap with the amino’s cognitive enhancing aims.

With that in mind, L-theanine may benefit weight loss by assisting with:

Appetite Regulation

“Stress eating,” though somewhat a funny meme these days, is a legit phenomenon linked to the body’s heightened craving for high-fat, energy-dense foods during conditions of chronic stress.

While appetite diminishes under acute stress, chronic stress amplifies the appetite to an excessive degree,5 which perhaps explains why stress-relieving L-theanine has been associated with appetite regulation.6

In animal (mice) research, the anti-obesity effects of three major components of green tea (catechins, caffeine, and theanine) were observed by a group of researchers. Based on their findings, the researchers concluded that “at least caffeine and theanine were responsible for the suppressive effect of green tea powder (GTP) on body weight increase and fat accumulation.”7

Dietary Energy Metabolism

As the previous study suggested, L-theanine in combination with caffeine may possess a suppressive effect on body weight increase and fat accumulation. This observation was also held by another animal study in which mice were fed either a normal diet, a high-fat diet (HFD), a high-fat diet with green tea (GT) containing L-theanine and caffeine, or a high-fat diet with catechins.

At the end of the study, the HFD with theanine-and-caffeine-rich GT was shown to reduce the fat-building effects of HFD. The researchers’ conclusion: “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.”8

Sleep-Related Fat Loss

You’re eating right, you’re exercising, and, yet, you simply aren’t seeing the weight loss results you’ve been imagining. Odds are this is because you’ve failed to address another key aspect of healthy weight management: sleep.

It’s well-known at this point that insufficient sleep undermines one’s dietary efforts to lose fat. As one study from 2011 distinctly puts it, “The amount of human sleep contributes to the maintenance of fat-free body mass at times of decreased energy intake.”9

What this means is that while one is quote-unquote “dieting” (or “decreasing energy intake”), sleep plays a key role in the diet’s effectiveness.

As a safe and effective supporter of sleep quality, L-theanine assists with one of the key factors involved in healthy weight loss—not to mention healthy lean muscle gains.10

Combine L-Theanine with Caffeine to Boost Fat Loss

Obviously, if you’re looking to increase fat loss by improving your sleep quality, you don’t want to stack L-theanine + caffeine together right before bedtime. However, during the daytime, the famous L-theanine + caffeine stack is an effective strategy to simultaneously:

  1. Acutely Boost Cognitive Performance
  2. Enhance Thermogenesis, or Calorie-Burning

Though many people would like to decrease their caffeine intake, few would like to eliminate caffeine from their diet altogether. It simply feels too good, and, frankly, there’s no denying the health and fitness benefits of just a little bit of caffeine.

This is partly why the L-theanine + caffeine combo is becoming increasingly popular among today’s health and fitness enthusiasts: by “smoothing out” the caffeine experience, L-theanine helps take off the jittery edge to caffeine’s stimulatory side effects while sustaining the stimulant’s energy-boosting, attention-promoting benefits.

In fact, L-theanine and caffeine seem to work better together than they do alone.

In addition to much of the research mentioned earlier, which pinpoints L-theanine’s fat-burning benefits generally on the L-theanine + caffeine combination, clinical research also suggests that “L-theanine and caffeine in combination are beneficial for improving performance on cognitive demanding tasks.”11

This means that you can enjoy L-theanine + caffeine not only for, say, enhancing your thermogenic calorie-burning capacity during exercise but also to improve your workplace performance.

For maximum benefits, take L-theanine and caffeine at an optimized 2:1 L-theanine to caffeine ratio—e.g., 100mg L-theanine, 50mg caffeine.

Best L-Theanine for Weight Loss: Suntheanine®

There’s L-theanine. And then there’s Suntheanine®, a 100% pure, nature-identical L-theanine brand clinically demonstrated to improve stress-related symptoms, attention, and other measures of cognitive performance.12 

Thanks to Suntheanine®’s purity, 100mg of this supplement supplies the L-theanine equivalent to 10 cups of green tea.

For optimal fat-burning, brain-boosting benefits, look for L-theanine as Suntheanine®, as used in the L-theanine-containing Performance Lab® Stim formula.

Performance Lab® Stim

Powered by L-theanine + natural caffeine (and more), Performance Lab® Stim is an ultramodern “Caffeine 2.0” stimulation stack designed for peak caffeine-driven thermogenesis and performance boosts minus the expected post-energy “comedown” and “crash” associated with stimulant use.

Taken first thing in the morning, midway through your work shift, before exercise, or whenever you need it, Performance Lab® Stim can help you stay energized and metabolically active throughout the day without compromising your sleep quality and cognitive composure.

And it’s all thanks to Stim’s unique selection of all-natural nootropics.

Key Features

  • Natural Caffeine (from Coffea robusta seeds), 50mg
  • Suntheanine® L-Theanine, 100mg
  • Ajipure® L-Tyrosine, 250mg
  • NutriGenesis® Caffeine Balance B-Complex:
    • Riboflavin+ (Vitamin B2), 500mcg
    • Vitamin B6+, 750 mcg
    • Folate+ (Vitamin B9),167 mcg DFE
    • Vitamin B12+, 2 mcg

The future of caffeine stimulation, Performance Lab® Stim advances the traditional “caffeine pill” formula with natural nootropics and a minimally effective dose of caffeine that actually delivers upon the stimulant’s energy and focus boosting benefits without the usual jittery side effects.

Altogether, Performance Lab® Stim’s stack splits into the following two sub-stacks:

#1 – Performance-Tuned Stimulation: here is the L-theanine + caffeine combo, a fat-burning nootropic duo demonstrated in clinical research to enhance attention, focus, and alertness by pairing caffeine’s stimulatory benefits with L-theanine’s mood-boosting relaxation effects.

#2 – Caffeine Balance and Recovery: to counteract caffeine’s heightened neurochemical demands on the central nervous system (CNS), Stim includes pro-catecholamine L-tyrosine (as premium Ajipure®) with a bioavailability-enhanced B-complex (as NutriGenesis®).

Matching the naturalness of Stim’s ingredients, Stim delivers its formula in all-natural, plant-based NutriCaps®, a patented capsule constructed out of fermented tapioca (pullulan) that’s completely devoid of any synthetics or artificial additives. Only clean, green thermogenesis here.

Key Benefits

The primary health and fitness benefits of Performance Lab® Stim fall under the following performance categories:

  • Nootropic: Stim improves alertness, mood, memory, focus, energy, and vitality with a mix of caffeine stimulation and natural nootropic brainpower.
  • Athletic: a popular pre-workout ingredient, caffeine (augmented by Stim’s nootropics) amplifies intensity, endurance, and both physical and competitive fitness.
  • Thermogenic: with the metabolic assistance of B-vitamins and L-tyrosine, caffeine raises calorie-burning metabolic performance for better fat loss and weight management.

While the L-theanine + caffeine duo here helps with thermogenic fat loss, the full Performance Lab® Stim formula assists with multiple aspects of physical and mental health and fitness.

With a manageable 50mg natural caffeine per serving, Stim offers a scalable source of caffeine, to be taken on an as-need basis per your personal caffeine tolerance and stimulatory needs.

Get the Best Deal on Performance Lab® Stim Here.

Conclusion: Does L-Theanine Work for Weight Loss?

Whether your goal is to improve your cognitive performance, burn off excess fat, get better sleep, or (D) all of the above, L-theanine works. Within the realm of natural nootropics, few (if any) possess as many multipurpose functions and benefits.

Granted, while L-theanine alone is a smart choice for general mood and focus enhancement, this supplement works particularly well with other ingredients, namely caffeine.

This means that simply adding L-theanine to your morning routine with your morning coffee, or taking a complete, complex formula like Performance Lab® Stim, will help you get more out of your day.

The final verdict: L-theanine is one of the best natural supplements you can add to your daily routine for an immediate boost on performance and a long-term adjustment in your overall weight, health, and fitness.



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  3. Nobre AC et al. L-theanine, a natural constituent in tea, and its effect on mental state. Asia Pac J Clin Nutr. 2008; 17 Suppl 1: 167-8.
  4. Nagao T et al. A green tea extract high in catechins reduces body fat and cardiovascular risks in humans. Obesity (Silver Spring). 2007 Jun; 15(6): 1473-83.
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