How effective is green tea for weight loss?

First, what differs green tea from other types of tea like oolong or black? Tea leaves come from the same Camellia sinensis plant, and they are green at harvest. If exposed to air for long, leaves darken and become "black" tea. If not, they remain green. Oolong tea is in between green and black tea.

Few studies examined the effect of tea on metabolism, fat oxidation and weight loss.

Physiologist William Rumpler studied the influence of oolong tea on energy expenditure. Four beverages were tested: full-strength tea, half-strength tea, water with caffeine, and water. Twelve men drank the beverages five times a day for three days. When the volunteers drank full-strength tea or water with caffeine, their metabolism was 2.9-3.4% higher than when they drank water, and they burnt on average 67 additional calories per day.

The study was rather short and limited, but it suggested that oolong tea helped to burn calories. However, burning 67 aditional calories a day cannot cause substantial weight loss. To lose a pound, you need to create a deficit of 3500 calories.

Another interesting thing is that full-strength oolong tea increased fat oxidation by 12%, that is tea can help the body use fat as an energy source. However, more studies are required to confirm this.

Japanese researches also examined the effect of oolong tea and green tea on metabolism. They concluded that oolong tea increased metabolism by 10%, green tea, by 4% for 120 minutes. However, it is not known if tea can increase metabolism for a longer period.

We were not able to find any studies that would confirm that green tea or oolong tea consumption could increase metabolism to the point that would cause weight loss of a pound a week. Claims that green tea extract can make you lose weight rapidly without diet and exercises are deceptive.

Green tea contains a large amount of caffeine. Before taking green tea, make sure you consult your doctor if you have heart problems, high blood pressure, kidney disease or nervous disorder.

Studies on the effect of green tea for weight loss were short and limited. More research is required to prove that the effect of green or oolong tea is strong enough to cause weight loss. Claims that green tea can make you lose substantial weight without diet and exercises are not scientifically feasible.

References

• Rumpler W, Seale J, Clevidence B, et al. Oolong tea increases metabolic rate and fat oxidation in men.
• Komatsu T, Nakamori M, Komatsu K, et al. Oolong tea increases energy metabolism in Japanese females.
• Healthwise Drug Guide. Green tea

Lose Weight with Green Tea: A Safe Weight-Loss Method That Works author: Patricia Rouner asin: 0961522178