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Green Tea
This power elixir has L-Theanine, an amino acid that may reduce anxiety as well as lower blood pressure, and ECGC, a plant compound that promotes fat burning. Lee says that while it also contains caffeine, most people find green tea calming rather than jittery-inducing. Keep in mind that iced green tea drinks can become diluted as the cubes melt, and even bottled varieties are often less concentrated than what you steep and sip hot at home.

Calories: 0