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Review Of Green Tea Extract As Recommended By Dr. Oz

Green tea extract has been getting a lot of buzz as a weight loss aid lately since Dr. Oz spoke of it on his show. In this post we’ll get down to the nitty-gritty on whether or not it’s a bona-fide thermogenic for fat loss or more hype than fact.

While I have a lot of respect for Dr. Oz and tend to line up with a lot of his recommendations, as always I’ve done my own homework and investigated the research to give you an unbiased review. I’m not trying to sell you any particular green tea extract product and this isn’t another one of those lame sales pages disguised as a review. At the end I’ll give you my opinion, but only after looking at the research and big picture.

What NOT to expect from green tea extract..

Let me preface this discussion by clearly stating what green tea extract is not. This shouldn’t come at a surprise but it’s not a quick-fix weight loss product or magic in bottle. If you’re hoping to take green tea extract pills and effortlessly lose pounds and inches you’ll be sorely disappointed, not to mention being a little lighter in the wallet.

The purpose of this review is to see if whether or not green tea extract can enhance fat loss in conjunction with diet and exercise, not all by itself. For a thermogenic to be effective with body composition changes it has to do more than just stimulate the central nervous system and increase your energy expenditure by miniscule amounts. If it were that simple you could just drink several cups of coffee per day and effortlessly lose weight.

In general, I’m highly suspect of most thermogenics because their impact on fat loss is widely exaggerated and over-hyped. People assume thermogenics are working to burn fat because they feel a rise in body temperature and get a surge in energy.

A lot of this is in the user’s head as stimulating the sympathetic nervous system doesn’t automatically equate to lipolysis or fat burning. The majority of “fat burners” available on the market today don’t show a lot of promise from what I’ve seen. Long gone are the days of ephedra and caffeine supplements that once ruled the market in the 80’s and 90’s.

Their replacements have continued to sell mostly due to marketing hype more so than legit science and real world results. That’s a whole subject for another discussion so let’s get back to green tea extract.

Why is green tea extracted being promoted for weight loss?

Here’s a quick breakdown on green tea. Of all the three main varieties of tea (green, black, and oolong), green tea is the least processed. The light processing of green tea helps to preserve its naturally high levels of antioxidants called polyphenols. The main active polyphenol in green tea is something called EGCG (epigallocatechin gallate).

Some research (as we’ll get into in a minute) has shown that the combination of EGCG and caffeine (like found in green tea) has an impact on energy expenditure. In other words, it increases the amount of calories your body burns at rest. How much so and whether or not this impacts fat oxidation is something we’ll have to investigate a little more as we go along.

So why the idea of taking green tea extract?

This is pretty simple to explain. By using the extract you can get higher concentrations of EGCG than drinking green tea. Consider the following:

A single cup of green tea provides somewhere around 20-35 mg of EGCG (depending on the purity and quality) while a high quality extract can provide 3-4 times that in a single capsule. So while drinking green tea certainly has numerous health benefits, you’d have to drink quite a bit of it to get much of a thermogenic effect.

Green tea extract and the impact on hunger levels…

One of the most beneficial qualities of green tea extract is the EGCG concentrations help to increase the hormone CCK (cholecystokinin). This is one of the hormones that plays a role in creating the feeling of satiation and fullness. Taking green tea extract does show some promise in helping to regulate appetite and keep the mindless snacking on sweets and unhealthy snacks at bay in between meals.

Research on green tea extract and 24 hour energy expenditure and fat oxidation…

I spent quite a bit of time going through the research on green tea extract and must admit I walked away without clear cut definitive answers. Most all of the research I found contained inconsistencies with the amounts of EGCG used in the testing.

Here’s a recap of what I found:

Effects of encapsulated green tea and Guarana extracts containing a mixture of epigallocatechin-3-gallate and caffeine on 24 h energy expenditure and fat oxidation in men.
Br J Nutr. 2005.  Laval University, Ste-Foy, Quebec, Canada.

Fourteen subjects took part to this randomized, placebo-controlled, double-blind, cross-over study. Each subject was tested five times in a metabolic chamber to measure 24 h energy expenditure, substrate oxidation and blood pressure. During each stay, the subjects ingested a capsule of placebo or capsules containing 200 mg caffeine and a variable dose of EGCG (90, 200, 300 or 400 mg) three times daily, 30 min before standardized meals.

Twenty-four hour energy expenditure increased significantly by about 750 kJ with all EGCG caffeine mixtures compared with placebo. No effect of the EGCG caffeine mixture was observed for lipid oxidation. Systolic and diastolic blood pressure increased by about 7 and 5 mmHg, respectively, with the EGCG caffeine mixtures compared with placebo. This increase was significant only for 24 h diastolic blood pressure. The main finding of the study was the increase in 24 h energy expenditure with the mixtures. However, this increase was similar with all doses of EGCG in the mixtures.


Ok for starters, what’s up with the variable dose? I’m not sure how to interpret this. If we were to assume that some individuals took 400mg of ECGC three times daily, that’s a LOT of EGCG! This would be way more than would be safe to consume. Consider the fact that most green tea extract pills contain around 100-150 mg total of catechins per serving.

Next let’s look at the statement that “twenty-four energy expenditure increased significantly by about 750 kJ.” Ok, in terms we can all understand this equates to about 179 calories. Big whoopee…this is not going to miraculously melt away pounds of body fat. They’ve shown that 24 hour energy expenditure has increased but I wouldn’t go so far as to use the word “significantly.” I guess that’s relative.

Here’s another…

American Journal Of Clinical Nutrition, December 1999 vol. 70 no. 6 1040-1045

Efficacy of a green tea extract rich in catehin polyphenols and caffeine in increasing 24-h energy expenditure and fat oxidations in humans.


Objective: We investigated whether a green tea extract, by virtue of its high content of caffeine and catechin polyphenols, could increase 24-h energy expenditure (EE) and fat oxidation in humans.

Design: Twenty-four–hour EE, the respiratory quotient (RQ), and the urinary excretion of nitrogen and catecholamines were measured in a respiratory chamber in 10 healthy men. On 3 separate occasions, subjects were randomly assigned among 3 treatments: green tea extract (50 mg caffeine and 90 mg epigallocatechin gallate), caffeine (50 mg), and placebo, which they ingested at breakfast, lunch, and dinner.

Results: Relative to placebo, treatment with the green tea extract resulted in a significant increase in 24-h EE (4%; P < 0.01) and a significant decrease in 24-h RQ (from 0.88 to 0.85; P < 0.001) without any change in urinary nitrogen. Twenty-four–hour urinary norepinephrine excretion was higher during treatment with the green tea extract than with the placebo (40%, P < 0.05). Treatment with caffeine in amounts equivalent to those found in the green tea extract had no effect on EE and RQ nor on urinary nitrogen or catecholamines.

Conclusions: Green tea has thermogenic properties and promotes fat oxidation beyond that explained by its caffeine content per se. The green tea extract may play a role in the control of body composition via sympathetic activation of thermogenesis, fat oxidation, or both.


This study basically showed that green tea extract had more impact on energy expenditure than caffeine alone. The amount of EGCG was more in line with a reasonable dose at 90 mg per. There’s still not much we can conclude as the summary concluded that green tea extract may play a role in thermogenesis, fat oxidation, or both (key word being “may”).

Conclusions…my take on all of this regarding green tea extract for fat loss

Let’s just say I’m not surprised by the findings that green tea extract helped to increase energy expenditure. But when you look at how much (couple hundred calories per day at best), this isn’t going to swing big doors with fat loss.

What I was really looking to find was the correlation to fat oxidation but there’s not much there. This doesn’t mean that EGCG doesn’t perhaps assist indirectly with fat oxidation but it’s certainly not a prime player.

Having said all that, I’m not dismissing the potential benefits of consuming green tea extract in conjunction with a healthy diet and exercise. There are certainly signs that indicate it may serve a beneficial role. Just don’t expect jaw-dropping results by taking a few pills and not changing much else with your diet or exercise.

I’m going to do some real world experimentation and research myself and follow up in a future post on the results. I think it’s worth experimenting with and since it’s a natural plant extract, I’m open to investigating further. This will get my attention and focus any day over the next big pharmaceutical diet pill.

How might you optimize the effects of green tea extract?

My recommendations would be to find a high quality green tea extract that shows signs of purity. Don’t go for the cheap variety found at your local CVS drug store. You may have to spend a little more but that’s the only way I’d go. I’ll let you know which brand I choose for testing after I do some research.


Post Update- 8/15/12

I wanted to update this post to include a recommendation on a green tea extract supplement. After extensive research I found very few retail green tea extracts at the popular vitamin shops that provided sufficient EGCG concentrations.

However, I was able to find an organic blend from Dr. Craig Koniver at Organic Medicine Now that provides 95% polyphenol contents.

Here’s a link to learn more about Green Tea Essentials and to order direct from his website.


What I’ll be doing is combining (3) doses of single serving capsules prior to each primary meal (breakfast, lunch, dinner). I wouldn’t advise going over the recommended dosage and trying to take a “shotgun approach.” As with anything there will be diminished returns with over-doing it.

This will be integrated into a Primal Blueprint type diet and 3-4 burst training workouts per week. This is the foundation of our programs at Shaping Concepts so I’ll be using this protocol albeit on myself or clients who choose to participate. Bodyweight and body fat percentages will be calculated prior to starting and 30 days after.

My reasoning for using burst training (aka “metabolic resistance training”) is I believe the hormonal and sympathetic nervous system response to this type of exercise will have the greatest synergistic impact with the green tea extract on fat oxidation. Interval training for cardio could also be included as that provides a similar response.

Lots of long-slow-distance cardio and severe calorie restrictive diets really aren’t my thing (because they work terribly) so I’ll be sticking with what I already have found to be effective. We’ll just be adding the green tea extract to the mix. Should you decide to go another route by all means go for it and fill me on what you find with the results.

So there you have it…Dr. Oz gives green tea extract a thumbs up and I can’t stand here and say I necessarily disagree with him. There are some signs that show promise, but let’s just say the jury is still out with me until I see some real world evidence.

The fact that I’m open to investigating it further will tell you I believe it’s worth the time to experiment with and that it’s proven to be safe with most individuals when used in moderation.

We’ll wait and see. If you’ve used or are using green tea extract I’d love to hear your comments and feedback. This is an open forum so feel free to leave your comments.

Shane Doll is a certified Charleston personal trainer, fat loss expert, speaker, and founder of Shaping Concepts Personal Training Studios. He specializes in helping people achieve a body transformation with burst training exercise and whole food nutrition. You can receive a FREE no-obligations trial of his Charleston personal fitness programs and start experiencing the Shaping Concepts difference today.

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Category: Supplements.