Green Tea Extract Increases Fat Burning Post Workout
Thermogenesis is the process of heat production in living organisms that can facilitate the fat burning process. The thermogenic effect of green tea is generally attributed to its caffeine content, however green tea extract has been shown to stimulate brown adipose tissue thermogenesis to an extent which is much greater than can be attributed to its caffeine content within itself. Green tea extract high thermogenic properties could potentially reside in an interaction between its high content in catechin-polyphenols and caffeine with sympathetically increases the fat burning hormone noradrenaline.
Since catechin-polyphenols are recognized to be capable of inhibiting catechol-O-methyl-transferase (the enzyme that degrades noradrenaline), and caffeine to inhibit phosphodiesterases (enzymes that break down noradrenaline -induced cAMP), it is assumed that the green tea extract, via its catechin-polyphenols and caffeine, is effective in stimulating thermogenesis by reducing inhibition at different control points along the noradrenaline -cAMP axis. This synergistic interaction between catechin-polyphenols and caffeine that augment and prolong sympathetic stimulation of thermogenesis could be of value in the obesity epidemic taking place in the United States.
Fat oxidation has been shown to increase after short-term green tea extract ingestion and after one bout of intermittent sprinting exercise. Whether combining the two will result in greater fat oxidation after of intermittent sprinting exercise is undetermined. Researchers investigated the combined effect of short-term green tea extract and a single session of intermittent sprinting exercise upon post-exercise fat oxidation. Fourteen women consumed three green tea extract or placebo capsules the day before and one capsule 90 minute before a 20-minute of intermittent sprinting cycling protocol followed by 1 hour of resting recovery. Fat oxidation was calculated using indirect calorimetry. At the end of the study, there was a significant increase in fat oxidation post-exercise compared to at rest in the placebo condition. After green tea extract ingestion, however, at rest and post-exercise, fat oxidation was significantly greater than that after placebo. Plasma glycerol levels at rest and 15 minutes during post-exercise were significantly higher after green tea extract consumption compared to placebo.
Compared to placebo, plasma catecholamines increased significantly after green tea extract consumption and 20 minutes after intermittent sprinting exercise. Acute green tea extract ingestion significantly increased fat oxidation under resting and post-exercise conditions when compared to placebo.
|Gahreman D, Wang R, Boutcher Y, Boutcher S. Green Tea, Intermittent Sprinting Exercise, and Fat Oxidation. Nutrients. 2015 Jul 13;7(7):5646-5663.|
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