In the phase of weight loss, as during weight maintenance, it is important to maintain as constant as possible the daily energy expenditure.
Indeed, daily caloric consumption usually decreases during weight loss.
Since the 90s of last century, it has been proposed that green tea, thanks to its content of caffeine and catechins, particularly epigallocatechin gallate (EGCG), which are also present in oolong tea and white tea, could be of help for:
- maintaining , or even increasing, the daily energy expenditure;
- increasing fat oxidation, thus acting as a fat-burning food.
Therefore, it was attributed to green tea the ability to cause a fat loss, and so to be of help for overweight or obese adults in achieving the ideal weight.
In addition to these potential lipolytic and thermogenic effects, catechins and caffeine may be useful by acting on other targets, such as the intestinal absorption of fat and the energy intake, probably through their impact on the gut microbiota and gene expression.
Therefore, products for weight loss and weight maintenance based on green tea extracts have been marketed. It should be noted that these products contain catechins and caffeine in amount much greater than the classic drink.
How much truth is there in green tea “fat burning” properties?
The issue seems to have been resolved by a careful meta-analysis of 15 studies on weight loss and intake of these “fat burning” products.
Eight of the 15 analyzed studies were conducted in Japan, and the rest outside of Japan, for a total number of 1945 subjects, which were followed for a period of between 12 and 13 weeks.
The study showed that the consumption of green tea-based products induces, in overweight and obese adults, a weight loss that is:
- not statistically significant;
- very small;
- probably not clinically important.
These “fat burning” products have not proved to be useful not even in weight maintenance.
Thus, on the basis of scientific evidence, green tea does not seem to be helpful in fat loss nor in weight maintenance.
There are no magic bullets: the only way to lose weight (body fat) and avoid future increases is to control your daily calorie intake and take part in physical activity on a regular basis.
Hursel R. and Westerterp-Plantenga M.S. Catechin- and caffeine-rich teas for control of body weight in humans. Am J Clin Nutr 2013;98:1682S-1693S doi:10.3945/ajcn.113.058396
Hursel R., Viechtbauer W. and Westerterp-Plantenga M.S. The effects of green tea on weight loss and weight maintenance: a meta-analysis. Int J Obesity 2009;33:956-961 doi:10.1038/ijo.2009.135
Jurgens T.M., Whelan A.M., Killian L., Doucette S., Kirk S., Foy E. Green tea for weight loss and weight maintenance in overweight or obese adults. Editorial group: Cochrane Metabolic and Endocrine Disorders Group. 2012:12 Art. No.: CD008650 doi:10.1002/14651858.CD008650.pub2