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Do Caffeine & Green Tea Stimulate Weight Loss?

Apr 23, 2011 | By Tracey Roizman, D.C.
Do Caffeine & Green Tea Stimulate Weight Loss?
Photo Credit green tea image by Ragne Kabanova from Fotolia.com

Green tea, made from the fresh steamed leaves of the Camellia sinensis plant, has been consumed for more than 4,000 years. Green tea, black tea and oolong tea are all made from the same plant, with slightly different cultivars and processing methods to create the different flavors and purported health effects. Green tea has been attributed with a variety of health benefits, including weight reduction. Consult your doctor before using green tea for weight loss.

Combination

Green tea combined with caffeine may be an effective weight loss-promoting combination, according to a study published in the April 2010 issue of the journal "Physiology and Behavior." Catechins and caffeine in green tea have been shown to have weight management effects by keeping certain neurotransmitters with stimulatory activity, such as dopamine and norepinephrine active. Caffeine promotes weight loss by increasing energy levels and preventing the decreased in metabolic rate that occurs during dieting as part of the body's protective response to conserve energy during periods of lower calorie consumption. The presence of both catechins and caffeine in green tea may have a synergistic effect that encourages fat burning and preserves lean tissue.

Abdominal Fat

Green tea catechins may enhance the weight loss benefits of exercise, according to a study published in the February 2009 issue of the "American Journal of Clinical Nutrition." Participants in the study consumed about 625 mg of green tea catechins along with 39 mg of caffeine per day for 12 weeks along with moderate exercise totalling at least thee hours per week. Although total fat loss was not increased in the catechin group, that group showed greater loss of abdominal fat and lower fasting triglyceride levels than a control group that did not consume green tea catechins.

Energy Expenditure

A study on the potential weight loss effects of a commercial caffeine-free green tea extract product found that the catechins in green tea were ineffective at promoting weight loss. In the study, published in the February 2011 issue of the journal "Obesity," young adult participants took green tea extract for 2 days, and the researchers found that resting metabolic rate was no greater in the green the group compared with a control group that did not take green tea extract. Similarly, green tea extract did not increase energy output after a meal -- a condition known as the thermic effect of feeding -- in the study. The researchers concluded that, in the short-term time frame of the study, green tea catechins without caffeine did not increase energy expenditure.

Green Tea Catechins

The "American Journal of Clinical Nutrition" published a study in its January 2010 issue that reported that green tea catechins without caffeine may produce only modest reductions in waist circumference and body mass index, a formula that determines a person's ideal height-to-weight ratio. In this meta-study, a review of previously published studies, researchers evaluated 15 studies and found that green tea catechins with caffeine effectively reduced several parameters of body weight compared with caffeine alone. Green tea catechins with caffeine also significantly reduced body weight compared with caffeine-free catechin extract. The researchers concluded that green tea catechins alone were not significantly effective at promoting weight loss to recommend them as a weight loss supplement in this study.

References

Article reviewed by Danielle Last updated on: Apr 23, 2011

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