Research Update! Is green tea extract the best fat burner for bodybuilders?

by Paul Cribb, B.H.Sci HMS
AST Director of Research

The compound Epigallocatechin gallate (just call it EGCG), is a naturally occurring polyphenol found in abundance in green tea. EGCG is this active ingredient within green tea extract that has recently been linked to so many health benefits, a number of scientists believe it to be the find of 21st century. In research, EGCG has shown the potential to prevent the progression of HIV, many forms of cancer, reduce blood cholesterol and the risk of cardiovascular disease and even prevent dental cavities! However, the research on EGCG’s unique capabilities as a fat burner are most intriguing.

The research findings on the effects of EGCG on the metabolism were so significant we decided that this compound should feature in our new NGRX™, TX-6™ and Pro-Therm™ formulations. The research on EGCG should be of great interest to all bodybuilders, for two important reasons.

Firstly, EGCG is shown in clinical trials to produce a thermogenic effect that enhances fat metabolism [1,4]. Unlike most of the research on fat loss compounds the positive effects of EGCG supplementation were demonstrated in people that were not fat. The second reason EGCG captured my interest is this compound appears to enhance fat loss via a different mechanism to other thermogenic compounds such caffeine and ephedra. Additionally, EGCG appears to enhance the effect of other thermogenic supplements such as caffeine and serve to prevent fat accumulation. These unique properties make EGCG a very interesting supplement to anyone that is concerned with shedding body fat.

EGCG: what is it, how does it work?

The catechin-polyphenols in green tea exist in several isoforms such as epigallocatechin (EGC), epicatechin (EC) and epicatechin gallate (ECG) but EGCG is believed to be pharmacologically, the most active tea catechin [5]. Side note: If a product label claims a supplement contains green tea extract, make sure it is standardized to contain a high dose of EGCG. If it does not, it will be useless as a fat- burner.

Several studies have investigated the effects of EGCG on fat metabolism. In general, these studies demonstrate that EGCG is a potent thermogenic compound (enables the body to expend calories as heat rather than storing them as fat). This effect has been demonstrated in research in a variety of mammals, including humans. Another interesting aspect of green tea extract is that its thermogenic effect is shown to be much greater than what could be attributed to its (naturally occurring) caffeine content. EGCG appears to be the active ingredient in green tea extract that provides very unique fat metabolizing capabilities [1-5].

It appears that EGCG acts synergistically with caffeine on the sympathetic release of noradrenaline to amplify caffeine’s effects [1-3]. Caffeine is a methlyxanthine and its stimulatory effect is thought to occur by increasing the concentration of norepinephrine at the synaptic junction in nerve cells – that’s why you get that subtle but very cool boost in mental focus and energy from a jolt of caffeine.

However, caffeine’s interaction with the adrenoceptors within these cells is negatively modulated through enzymatic degradation by catechol O-methyltransferase (COMT) - the enzyme that degrades noradrenalin (and diminishes the boost). Some research shows that the noradrenalin degradation enzyme COMT can be inhibited (shut down) by certain plant polyphenols, most notably EGCG! [5] Thus, EGCG supplementation may serve to amplify and prolong the effect of caffeine on noradrenalin release. In turn this increases cAMP which boosts energy metabolism and thermogenesis. Therefore, EGCG appears to be a perfect compound to “stack” with methlyxanthines such as caffeine and theobromine – this combination will provide a synergistic effect on the metabolism that may enhance fat metabolism.

The latest research on EGCG . . .

The intense interest in green tea extract as a fat-burner originated from in vitro (test tube) research. These studies showed that EGCG was actually more effective than equivalent amounts of caffeine or ephedrine in activating thermogenesis!

Abdul Dulloo and his colleagues are the group of scientists that performed the land-mark, six-month study on the safety and effectiveness of ephedra and caffeine for fat loss. However, this group of scientists were also the first to show that a daily dose of green tea extract significantly stimulated thermogenesis, increased daily energy expenditure and fat oxidation in non-obese humans [1].

Treatment with the green tea extract resulted in a highly significant (P < 0.01) increase in 24-hour energy expenditure and a highly significant decrease in 24-hour respiratory quotient (RQ) without any change in urinary nitrogen [1]. Twenty-four hour urinary norepinephrine excretion was 40% higher during treatment with the green tea extract than with an equivalent dose of caffeine. Interestingly, treatment with caffeine in amounts equivalent to those found in the green tea supplement had no effect on energy expenditure and RQ or on urinary nitrogen or catecholamines. These results clearly indicate that the EGCG green tea extract increased metabolic rate and fat oxidation to a much greater extent than caffeine alone. Additionally, the researchers recommended that green tea’s potent effect on the metabolism could not be explained by the supplement’s caffeine content.

In this research the treatments were administered in a double-blind design with a 5 to 10-day interval between successive 24-hour trials for each subject. During the entire study period (lasting 5 to 6-weeks), the subjects were prescribed the same diet. The capsules containing the green tea extract provided a daily total of 150-mg caffeine and 375-mg catechins, of which 270-mg was EGCG. The fat loss effects become particularly relevant to bodybuilders when you consider that the participants in this study were healthy people that were not obese or overweight [1].

Based on the findings, the researchers suggested that the fat loss effects derived from the green tea extract EGCG had to occur via a different mechanism to the characteristic beta-agonist (stimulation) that caffeine provides. More importantly, the researchers provided evidence that support these suggestions. Although the green tea extract was effective at increasing thermogenesis and fat oxidation, it did not raise the participant’s heart rate or blood pressure!

The same scientists then demonstrated the same metabolic effects in rodents and concluded that a clear synergistic interaction is evident between the catechin-polyphenol EGCG and caffeine; these two compounds work together to enhance sympathetic stimulation, thermogenesis and fat burning [2]. Since then, a number of other studies have not only confirmed the thermogenic, fat burning properties of EGCG, they have revealed additional fat loss benefits from supplementing with this compound [3-5].

A most interesting study on the effects of green tea extract on body fat accumulation was completed by Murase and colleagues [3]. In a group of mice that were fed a high fat diet, these scientists demonstrated that supplementation with green tea extract (containing 75% EGCG) resulted in a reduction in body fat despite the high fat consumption [3]. The EGCG-supplemented mice showed significantly increased acyl-CoA oxidase and medium chain acyl-CoA dehydrogenase mRNA expression as well as beta-oxidation activity in the liver. This biochemistry “gobbledygook” simply means that green tea supplementation provided a protective effect against fat accumulation in the face of a high-fat diet—these biological markers are all examples of an up-regulation in the ability to burn fat for energy.

Just last year French scientists Chantre and Lairon showed that a three month treatment with EGCG was effective in treating moderately obese patients.4 After the 3 month trial, body weight was decreased by 4.6% and waist circumference by 4.48% in those given EGCG [4]. These results were significant compared to the placebo treatment.

In summary, the amount of research published this year on the health benefits of EGCG makes this supplement tremendously important to any person concerned with building a premium body that excels in athletic performance. Regarding fat loss, the positive effects of EGCG on fat metabolism are clear (which is more than you can say for most of the compounds marketed as “fat loss” supplements). EGCG appears to stimulate thermogenesis and fat utilization via a different mechanism to other fat loss compounds. Additionally, EGCG appears to cause no unwanted side effects while enhancing the effects of other fat loss compounds such as caffeine. Scientific evidence has revealed the tremendous attributes of EGCG; it is a compound that shows great potential for enhancing athletic performance and fat loss.

References:

1. AG Dulloo, C Duret, D Rohrer, L Girardier, N Mensi, M Fathi, P Chantre and J Vandermander. Efficacy of a green tea extract rich in catechin polyphenols and caffeine in increasing 24-h energy expenditure and fat oxidation in humans. American Journal of Clinical Nutrition, Vol. 70, No. 6, 1040-1045, 1999.

2. A G Dulloo, J Seydoux, L Girardier, P Chantre and J Vandermander. Green tea and thermogenesis: interactions between catechin-polyphenols, caffeine and sympathetic activity. International Journal of Obesity 24, 252-258, 2000.

3. T Murase, A Nagasawa, J Suzuki, T Hase and I Tokimitsu. Beneficial effects of tea catechins on diet-induced obesity: stimulation of lipid catabolism in the liver. International Journal of Obesity 26, 1459-1464, 2002.

4. Chantre P; Lairon D. Recent findings of green tea extract AR25 (Exolise) and its activity for the treatment of obesity. Phytomedicine 9 (1):3-8, 2002

5. Hertog MGL. Epidemiological evidence on potential health properties of flavonoids. Proc Nutr Soc 55: 385-397, 1996