I would recommend going for plain organic green tea

Green tea has been investigated and researched to determine its medical and health related benefits. It has been claimed to reduce the chance of certain cancer, heart disease, improve ratio of HDL/LDL cholesterol, increase bone density and much more. Many of the listed benefits attributed to green tea are of anti ageing nature, and are related to prevention of conditions typical to the ageing population. In the past decade, green tea has been associated with weight loss too.
Basically, there are two ways to control weight: reduction of food consumption (energy intake) or increasing energy expenditure (EE). Fat oxidation (fat metabolism) and thermogenesis (heat generation) in the body are under the control of the Sympathetic Nervous System (SNS) – the “fight or flight” branch of the nervous system. Just before any activity, the SNS is activated to produce the energy needed for the mission, this process includes activation of chain reactions that process glucose and fatty acids to release energy needed for the activity or for increasing body temperature. Triggering of the SNS involves neurotransmitters like norepinephrin which is released by the brain and by the SNS and triggers the chain reactions in the cells it attaches to. Since increasing metabolic rate and increasing temperature requires energy, it makes sense to try and target the SNS path for the sake of “burning energy” hence weight control.
Green tea is rich in Flavonoids, particularly tea catechins, which have been tested to have an inhibiting effect on the enzyme that breaks down the neurotransmitter and hormone mentioned above norepinephrin. In addition, Catechines increase insulin sensitivity, thus increasing glucose uptake within the skeletal muscles.
A study conducted at The University of Birmingham, UK, examined the effect of green tea extract on fat oxidation rate and on glucose tolerance during moderate intensity cycling in healthy men.
The study results exhibited a 17% increase in the oxidation rate of fat compared to the control group treated with placebo. The study also demonstrated an increase in Insulin sensitivity therefore, less insulin is needed to control glucose blood level, hence more glucose can be “processed” with less insulin (keeping glucose blood level lower with less insulin).
This means that consuming green tea will actually cause one to “burn” more fat while exercising and at rest.
This study is one of several that demonstrate the effectiveness of green tea for increasing the rate of fat metabolism. A different study demonstrated a 30% increase in metabolism rate during rest when green tea is consumed.
If you plan to “shape up” in a healthy manner, without starving yourself, and by increasing physical activity, it is a good idea to also add green tea to your diet. However, losing weight will not necessarily improve skin texture and appearance. It is a good idea to combine diet and lifestyle changes with existing technologies that target specific aesthetic issues, like cellulite, that cannot be improved by diet, green tea or exercise. Combining strong will with the help of existing technologies can also increase the incentive to diet as the results will be faster and better.
So, next time you need to choose a tea bag from a variety of existing beverages, select the green tea package and enjoy the healthy outcome. (I would recommend going for plain organic green tea, without flavors.)