Definition: "An ergogenic aid is any substance or phenomenon that enhances performance "

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Weight loss supplement green tea works better without protein

After governments outlawed ephedra, manufacturers introduced all sorts of slimming supplements based on green tea. The products work wonderfully in the lab, but not always in practice. Researchers at Maastricht University in the Netherlands have found out why. The proteins in your food neutralise the active ingredients in green tea.

The researchers first got eighty obese people to lose weight on a strict astronaut diet of five hundred kilocalories per day for four weeks. Then the test subjects had to try to maintain that weight for thirteen weeks. It was during those thirteen weeks that the experiment took place.

The researchers gave half of the test subjects a daily supplement containing 270 mg of the green tea flavonoid EGCG [structural formula shown above] and 150 mg of caffeine [structural formula shown below]. The other half of the subjects were given a placebo.

Caffeine increases adrenalin production and also makes the body's cells more sensitive to the hormone. Adrenalin induces fat cells to release their content into the bloodstream and increases the amount of energy burned in the tissues. EGCG blocks the breakdown of adrenalin and directly raises the level at which the cells burn fats.

An additional factor that keeps weight down after doing a slimming diet is a protein-rich diet. The researchers in Maastricht wanted to know whether the slimming effect of a protein-rich diet and that of the EGCG/caffeine stack reinforced each other. So they put half of the stack users and half of the placebo takers on a protein-rich diet. The other half of the two groups were given a diet with a normal amount of protein.

Don't forget, the researchers are nutritionists, not athletes. In their eyes, a protein-rich diet [HP] provides 100-120 g of protein daily, and a diet with a 'sufficient quantity of protein' [AP] contains 50-60 g per day.

The figure below shows the results for the four groups at the end of their four-week diet.

Weight loss supplement green tea works better without protein

And here below you see what happened to the test subjects during the thirteen weeks of weight maintenance. The high-protein diet helps to keep body fat mass down, and the EGCG/caffeine stack does the same. But they don't reinforce each other's effect.

Weight loss supplement green tea works better without protein

The researchers found an explanation in the literature. EGCG is a polyphenol, and polyphenols are easily deactivated by proteins. For those who like to know the scientific term: the process is called noncovalent crosslinking. The polyphenols have a preference for proteins with a high level of the amino acid proline favourites are the caseins in dairy, especially the protein-rich betacasein. If caseins are not present, alpha-lactalbumin and beta-lactoglobulin also do the trick.

Even tiny quantities of protein in food have an effect. According to some epidemiological studies, the positive health effects of tea disappear even if just a dash of milk is added. If you eat large amounts of protein during the day, they will neutralise all those good substances in green tea.

So now a protein-loving ergonaut with an EGCG craving knows what to do to get the most out of green tea stacks: take your daily dosage in one go first thing in the morning, and wait about an hour before eating any proteins. If you hands start to shake, then you know you're on the right track.

Am J Clin Nutr. 2009 Jan 28. [Epub ahead of print].

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