A well-known compound found in green tea is called EGCG (which stands for epigallocatechin-3-gallate). EGCG is associated with enhanced metabolic activities that may prevent weight gain or assist with weight maintenance. Some of the ways that EGCG seems to work is by boosting thermogenesis (the body producing heat by using energy) and suppressing appetite, although not every study has found evidence that these effects are substantial.
In addition to actual tea, detox concoctions typically include additional herbs, which may be designed to curb appetite, rev metabolism, or boost weight loss in other ways. One example is senna, a plant with a natural laxative effect. According to the Natural Medicines Comprehensive Database, the potential side effects of senna use may include abdominal pain and discomfort, cramps, bloating, gas, nausea, and diarrhea; excessive use can lead to potassium depletion and other electrolyte abnormalities, which can trigger muscle spasms and an abnormal heart rhythm. Another popular ingredient in weight loss teas is guarana, a plant that's often added to energy drinks. Its side effects are commonly related to its caffeine content, which may include nervousness, restlessness, stomach irritation, nausea, vomiting, headache, anxiety, agitation, ringing in the ears, and fast heart and breathing rates. Bottom line: Do your homework about exactly what's in a product before you put it in your body. Even "all-natural" substances can have potential side effects, especially if they're overused, combined with other supplements or medications that result in negative interactions, or if taken by those with pre-existing medical conditions.
Shade grown: All matcha is made from shade-grown tea leaves—a labor-intensive process where tea bushes are protected from the sun and light is filtered to the bushes in a very controlled manor. Shading boosts the chlorophyll production in the plant, giving the leaves a rich green color. The lack of sun reduces the plant’s photosynthesis of the leaves, which in turn alters the naturally occurring levels of caffeine, flavanols, sugars, antioxidants, and theanine. By controlling the sun exposure, tea producers can significantly alter the chemical make-up and flavor of the final tea leaves.