L-theanine is a naturally occurring amino acid found primarily in green tea leaves. It does an excellent job at relaxing without being a sedative making it an excellent choice to pair with stimulants.
Theanine is an amino acid found in green tea, and is probably the reason why drinking green tea help in weight loss. Studies have found that weight gain is prevalent in people who are emotionally stressed. This is a biological response of our metabolism and leads to cravings and overconsumption of food. When stressed, we produce increasing amounts of a hormone called cortisol. This is a natural response that is intended to help in survival, which as a consequence also leads to increased fat storage. Theanine neutralizes stress, by reducing anxiety and improving the quality of sleep. It does this by increasing the alpha waves in your brain, which relaxes the mind.