It’s a dieter’s dream come true: a hot drink that helps you burn fat… and still keeps on working even when you’re asleep.
New research from the University of Tsukuba suggests oolong tea might just fulfil that dream.
Oolong tea is made from the same plant as other teas, but the leaves are partially oxidised (green tea is not oxidised and black tea is fully oxidised).
Previous research has suggested that green tea has a measurable (but small) impact on weight loss - and the University of Tsukuba researchers wanted to understand whether oolong had a similar effect.
In a two-week test, researchers found that drinking oolong tea increased fat breakdown by 20% in healthy volunteers, similar to the figure for another group who consumed pure caffeine.
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Professor Kumpei Tokuyama said, "The stimulatory effects of oolong tea on fat breakdown during sleep could have real clinical relevance for controlling body weight.
“However, we need to determine whether the effects we observed in the two-week study translate into actual body fat loss over a prolonged period.
“In addition, we want to trial a decaffeinated oolong tea to better distinguish the effects of caffeine from other components of tea, which will help us understand exactly how oolong helps with fat breakdown."
The volunteers developed a tolerance to the stimulant effects of caffeine over the two weeks of the study, Tokuyama said.
There was no noticeable difference in sleep patterns or the time it took participants to fall asleep between the treatment and placebo groups, the researchers say.
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This suggests that drinking oolong tea is unlikely to prevent you from getting a good night's rest, the researchers say.
Tokiyama said, "Like all teas, oolong contains caffeine, which impacts energy metabolism by increasing our heart rate.
“However, studies suggest that tea consumption may also increase the breakdown of fat, independent of the effects of caffeine.
“We therefore wanted to examine the effects of oolong consumption versus caffeine alone on energy and fat metabolism among a group of healthy volunteers."
Previous research has shown that drinking coffee can have an impact on weight gain.
Researchers found that swilling down a hefty dose of coffee improved liver health in mice – reversing non-alcoholic fatty liver disease – and meant that mice gained less weight.
Last year, Harvard researchers found that drinking up to five cups of coffee a day had various big health benefits.
Researchers from Harvard T.H. Chan School of Public Health found that people who drank three to five cups per day had a lower risk of cardiovascular disease, neurological diseases, type 2 diabetes and suicide.
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