Green tea has no relevant long-term effect on fat loss
Green tea is usually marketed as the “natural fat burner” and admittedly, there is some literature supporting this claim, finding some statistically significant effects on fat oxidation. These findings are used to mislead the public! Remember that fat oxidation is only part of the equation when looking at fat balance as one needs to consider fat storage as well. What really needs to be measured is fat mass.
A meta-analysis (a process where many studies are critically analyzed by statistical professionals) from 2015 found that green tea’s effect on fat mass was statistically significant, but at a level of -0.76% during a 12 week period. This means that even if the change is STATISTICALLY significant, it is not PRACTICALLY RELEVANT as these levels are minimal. Most studies showing effects are short term studies, and long term effects of green tea have never been seen unless the tested population was in a caloric deficit.
Green tea may counteract the body’s decrease in metabolism (BMR) which occurs during a caloric deficit, and thus have this minimal effect, but at the end of the day the calories and foods you consume are much more important for you reaching your weight loss goals. Don’t forget, though, that green tea may have other beneficial effects outside of fat loss, such as better sleeping patterns and effects on mood, but these are areas in which more studies are needed.
1: Baladia E. [Effect of green tea or green tea extract consumption on body weight and body composition; systematic review and meta-analysis]. Nutr Hosp. 2014 Mar 1;29(3):479-90.
2: Janssens PL. Long-term green tea extract supplementation does not affect fat absorption, resting energy expenditure, and body composition in adults. J Nutr. 2015 May;145(5):864-70.
3: Janssens PL. Nutraceuticals for body-weight management: The role of green tea catechins. Physiol Behav. 2016 Feb 1. pii: S0031-9384(16)30039-7.