Does green tea enhance the effect of exercise?
Green tea adds a small but measurable extra effect on top of exercise in terms of weight loss and inflammatory markers. For athletic performance and muscle mass, the evidence is too thin for firm conclusions.
Ten randomised studies combined show that green tea taken alongside exercise produces a small but measurable additional weight loss compared with exercise alone, in people who are overweight or obese. The standardised difference is approximately -0.30, which is small but statistically reliable. For blood lipids such as cholesterol and triglycerides, green tea adds nothing on top of exercise.
Green tea extract at 500 mg per day, combined with eight weeks of endurance training, reduces inflammatory markers more than exercise alone, and raises levels of the beneficial hormone adiponectin. In the same study of 45 overweight men, the muscle hormone irisin increased only in the group that also took green tea. What that last finding means in the long term is not yet clear.
A small study of 78 older adults, funded by a green tea manufacturer, found that 613 mg of catechins per day combined with exercise had a favourable effect on lower-body muscle strength, but no effect on muscle mass or general physical performance. Because of the manufacturer's involvement, this result needs to be confirmed in independent research.
The picture for fat oxidation during exercise is mixed. A small study of 13 women showed that matcha slightly but significantly increased fat oxidation during brisk walking (from 0.31 to 0.35 grams per minute), though the authors themselves caution that this effect should not be overstated as a weight-loss strategy. Another small study found a greater improvement in fat oxidation only with a combination product containing additional antioxidants, not with green tea extract on its own. Whether green tea improves athletic performance remains uncertain on the basis of current research.
The answer rests on ten randomised studies that were analysed together for weight and fat mass, supplemented by smaller individual randomised studies on inflammatory markers, muscle strength and fat oxidation. The researchers themselves describe the findings on body composition as inconclusive and call for further research. The study on muscle strength in older adults was partly funded by a green tea manufacturer, which limits the reliability of that specific result. For fat oxidation and athletic performance, the studies are too small for firm conclusions.