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Metastudy: slimming supplements with green tea do work

Metastudy: slimming supplements with green tea do work
Ephedra-free stackers containing caffeine and extracts of green teado help to reduce the amount of body fat. Pharmacologists from the University of Connecticut reached this conclusion after performing a metastudy in which they analyzed the data from 15 human studies. In many studies the effect is not very big but they do confirm that you can lose weight more quickly with green tea stackers.

Phenols in green tea inhibit the enzymes that break down the pep hormones adrenalin and noradrenalin. More adrenalin and noradrenalin means that the fat cells release their contents more easily into the bloodstream, so that the muscles and organs can burn these. At cell level, the phenols have a similar effect, recent studies suggest. Phenols in green tea, such as EGCG, cause the mitochondria in the cells to burn more fatty acids. Caffeine makes cells more sensitive to adrenalin and green tea. And there you have the rationale behind slimming supplements that contain green tea and caffeine.

Take an example: give healthy men who generally speaking don't use caffeine containing food 150 mg caffeine, and their fat burning goes up by 33 percent. Add to this 270 mg ECGC, the most active polyphenol in green tea, then their fat burning goes up by 41 percent.

In the studies that the researchers re-analyzed, the test subjects had been given an average of 580 mg phenols [actually catechins] from green tea and about 415 mg caffeine daily. The studies lasted from 8-24 weeks.

The figure below shows that in the trials the combination of green tea and caffeine resulted in an average bodyweight loss of half a kilogram.

Metastudy: slimming supplements with green tea do work

What's interesting is that the catechins in green tea have no effect on their own. They only become effective when taken in combination with caffeine.

The effect on the waist measurement is shown below. The average difference is less than a centimetre. Once again, catechins are only effective in combination with caffeine.

Metastudy: slimming supplements with green tea do work

The researchers' modest results do not do justice to what it's possible to achieve by combining EGCG and caffeine. The results say more about the low doses used in the studies.

In a more recent study, in which subjects took 600 mg caffeine and 1200 mg EGCG, the test subjects burned 197 kcal than normal daily. That makes a difference of one kilogram fat in just 36 days.

Am J Clin Nutr. 2010 Jan; 91(1): 73-81.

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