Can drinking tea really help you lose weight?

That seems to be the big question to which everyone really wants a clear answer.

A quick PubMed search revels nearly 1000 articles examining the link between tea and body weight. In fact, researchers from Japan to Thailand to Oklahoma have all tried to answer that question, and more importantly, find out why certain results occur when drinking tea or taking tea extracts.

microscopeTo narrow down our review of the research, let’s first eliminate all studies done on mice or rats and focus solely on research in human subjects.

Even with narrower parameters, to get a clear answer to the question ‘does tea drinking help with weight loss?’ is no easy task. Indeed, the research is very mixed, with some studies suggesting that yes, tea makes a difference to body fat and weight, and others suggesting tea is no more beneficial than its caffeine content working via thermogenic effects.

Those that say ‘No’

A study conducted in the Netherlands and published in the British Journal of Nutrition, found that the consumption of green tea extracts (GTE) offered no additional benefit to reducing body weight or improving body composition in subjects fed a very low energy diet.  While GTE did offer some effect on maintaining resting metabolic rate even with a low calorie diet, it was not significant enough to impact overall body weight or composition during the 32 day study.

Another study came to a somewhat similar conclusion, noting that tea matters less than caffeine when it comes to weight loss. The study, published in Obesity Research, showed that reductions in body weight were driven largely by caffeine, rather than green tea catechins, including specifically epigallocatechin gallate (EGCG). According to the researchers at the end of the 4 month study, “Taken together, we conclude that habitual high caffeine intake was associated with a greater weight loss and relatively higher thermogenesis and fat oxidation. A mixture of green tea (epigallocatechin gallate) with caffeine was associated with greater weight maintenance in habitual low caffeine consumers, supported by relatively greater thermogenesis and fat oxidation.” [emphasis added] To summarize, tea matters less than caffeine in weight loss and maintenance.

‘Maybe, with exercise’

A 12-week study compared the effects of green tea catechins with caffeine versus caffeine without green tea catechins, when combined with exercise. The abstract suggest the researchers came to the conclusion that catechins and caffeine matter more than caffeine alone in individuals who are exercising. However, digging deeper into the paper, the authors state: “The additional fat loss observed in the catechin group of 0.6 kg or 1.7% (P = 0.208) was not significant, so it cannot be reliably separated from random variation. However, this represents a difference in energy balance of ∼252 kJ (60 kcal)/d. Therefore, our results are not inconsistent with the possibility that catechin consumption increases energy expenditure to a degree that could produce clinically important changes in body fat over time. Larger and/or longer trials will be needed to test this hypothesis.”

Blogger’s Note: I find that far less of an endorsement than the premise put forth in the abstract, and far less of a resounding endorsement for the benefits of catechins. This study was funded by Kao Corporation, which makes a bottled green tea for the Japanese market. 

‘Yes’ said these studies

A 12-week study conducted in Thailand and published in Physiology and Behavior compared green tea versus placebo on a study of obese Thais in a food-controlled environment. The authors concluded that “green tea can reduce body weight in obese Thai subjects by increasing energy expenditure and fat oxidation [burning].”

A National Institute of Health-funded study compared green tea versus GTE. The 8-week study had only 35 participants, who were split into 3 groups. The green tea drinkers had 4 cups of tea per day, while GTE was provided in 2 capsules per day and that group was instructed to drink 4 cups of water per day, and the control was instructed to drink 4 cups of water per day. “Pairwise comparisons showed green tea beverage and green tea extracts caused a significant decrease in body weight and body mass index (BMI) versus controls at 8 weeks.” The researchers attributed this to “Plasma free catechins were detectable in both beverage and extract groups versus controls at screen and at 8 weeks, indicating compliance and bioavailability of green tea catechins.” Green tea drinking resulted in a slightly lower body weight than GTE.

A 12-week double-blind, randomized, placebo-controlled group comparison studied the effects of powdered barley tea with Pu-erh extract versus powdered barley tea without (placebo).  Researchers continued to follow the pre-obese Japanese study participants even after Pu-erh extract supplementation had been stopped, and found significantly reduced visceral fat in the pu-erh treated group. The researchers concluded “Ingestion of BTE (Pu-erh extract) exhibited significant effects in reducing the mean waist circumference, BMI, and visceral fat values and might be useful for weight control and prevention of obesity development (or metabolic syndrome) in humans.”

A Meta-Analysis

With hundreds of studies on the effects of tea in reducing body weights, it is impossible for me to review all of them, including methodology, funding sources, results, etc.  That is why researchers sometimes conduct a meta study, to examine all the existing research on that topic.  One such meta study appearing in the International Journal of Obesity narrowed 49 articles down to 11 for review, and concluded that tea improves weight loss and weight maintenance efforts (following a period of weight loss), but those effects are moderated based on habitual caffeine intake and ethnicity.

Choose Belight Tea

Given that the research is very mixed, what does this mean for you? Does this even answer the question, ‘does tea drinking improve weight loss and body composition?’

The research does not provide a clear cut yes or no. What it does tell us, is that there is no harm in drinking more tea, likely only endless benefits, but clearly, when it comes to weight loss and weight maintenance, lifestyle factors and habits are more important.  That’s why, with Belight Tea we encourage people to drink Belight Tea as an alternative to an afternoon snack or sugary drink to aid in their weight loss efforts.