Green Coffee Beans and Weight Loss. Do They Really Work? Critical Review

Does green coffee bean help people lose weight?  That’s a question a lot of people are asking since seeing this weight loss supplement on the Dr Oz show. If you’ve been wondering about this also -or wondering if it's a scam – let me try to help you make sense of things by looking at the green coffee bean weight loss research. I believe that only by reviewing it according to its research can we cut through the hype that permeates most websites and magazines about this product.

 

What is Green Coffee Bean?

Green coffee beans are coffee beans that have not been roasted. Roasting green coffee beans not only changes the color of the coffee beans but also removes a compound called chlorogenic acid (say klor-oh-jen-ick acid).

It's chlorogenic acid that is at the heart green coffee bean weight loss claims. Roasted coffee beans have little chlorogenic acid.

 

When supplements contain “green coffee bean extract”, chlorogenic acid is the extract they are referring to. Like many plant chemicals, chlorogenic acid also has antioxidant properties. Another extract of green coffee beans that is probably also used in supplements is caffeine.

 

According to the chlorogenic acid Wikipedia page and the  Autoimminity Research Foundation foods that naturally contain chlorogenic acid include:

1. Prunes
2. Peaches
3. Tea
4. Blueberries
5. Sunflower seeds

So, if you are eating these foods, you are getting chlorogenic acid already.

How Does It Work?

The research so far tends to say  that chlorogenic acid (an extract in green coffee bean) disrupts an enzyme called glucose-6-phosphatase, which is involved in how the body used glucose (sugar). I think things might be more complicated than this so I will leave the question of “how it works” to others.

Green Coffee Bean Weight Loss Research

There is research on green coffee beans and weight loss. Below are summaries of some of those studies. While many of the studies involve lab animals, where possible, human research will be highlighted also.

 

In a mouse study published in 2006 titled Inhibitory effect of green coffee bean extract on fat accumulation and body weight gain in mice  researchers noted that a green coffee bean extract reduced blood triglyceride levels.

 

However,  the researchers also noted that neither chlorogenic acid or caffeine by itself was successful at reducing body weight gain or fat accumulation in the belly.

In a 2007 study titled The Effect of Chlorogenic Acid EnrichedCoffee on Glucose Absorption in HealthyVolunteers and Its Effect on Body Mass When Used Long-term in Overweight and Obese People, researchers compared different types of coffee in 30 healthy, normal weight people.  The study lasted 3 months (12 weeks).

The green coffee tested was called “Coffee Slender.” This product contains 200 mg of a green coffee extract called Svetol.

People drank 5 cups of Slender Coffee – or regular coffee – per day for 3 months.

Results: researchers noted that people drinking Slender Coffee lose about 12 pounds compared to placebo coffee (compared to 3.5 pounds with the placebo coffee).

Researchers also noted that those drinking Slender coffee people lost more body fat, but but body fat was measured using bio-electric impedance which might not be as reliable as other methods.

In 2011 there was a study titled The Use of Green Coffee Extract as a Weight Loss Supplement: A Systematic Review and Meta-Analysis of Randomised Clinical Trials

A meta analysis looks at previous research and tries to lump all similar studies  all together —using statistics— to see if, taken as a whole, a common trend or out outcome can be determined. In this case, the meta analysis was trying to see if there was enough evidence to say “Yes or no on the question of green coffee bean and weight loss.“

 

This meta analysis was said to only included the best quality studies – randomized, placebo controlled double blinded clinical studies using overweight humans. Of over 2000 studies that were found, only 3 studies met the criteria of the researchers. These 3 studies used a total of

143 people.

 

These were the 3 studies that were included:

• The effect of chlorogenic acid enriched coffee on glucose absorption in healthy volunteers and its effect on body mass when used long-term in overweight and obese people (published 2007).

• Independent market study on the effect of coffee shape on weight loss—the effect of chlorogenic acid enriched coffee (coffee chape) on weight when used in overweight people. (study can't be located online).

• Svetol^®, green coffee extract, induces weight loss and increases the lean to fat mass ratio in volunteers with overweight problem. (study can't be located online).

Here is Svetol on Amazon.

 

Taken as a whole, these 3 papers appeared to show that overweight people who use green coffee bean extract have significantly greater weight loss than people who used a placebo. That’s good, but the researchers went on to say  that the degree of this effect was “moderate” and that  the “clinical relevance is therefore not certain.” The researchers go in to say that “the size of the [weight loss] effect is small.”

 

In other words, the researchers were saying that while a moderate amount of weight loss seemed to be occurring, it's hard to tell for sure because of the lack of good, quality studies.

 

In 2012 a study titled  Randomized, double-blind, placebo-controlled, linear dose, crossover study to evaluate the efficacy and safety of a green coffee bean extract in overweight subjects  (this study has been retracted. See update below) was published in the journal, Diabetes Metabolic Syndrome and Obesity. This study was conducted in India, involved just 16 people and lasted 22 weeks (5.5 months) and involved 16 overweight men and women.

This was a pretty small study. This was an investigation of a green coffee bean supplement called “GCA” made by Applied Food Sciences  (appliedfoods.com) who funded the study. All subjects received the same treatments (for 6 weeks each) in a double blinded, random order. The treatments were:

• Placebo (not specified) given 3x per day
• 350 mg GCA taken 3x per day (1050 mg total)
• 350 mg GCA taken 2x per day (700 mg total)

A period of 2 weeks separated treatments to let the compounds wash out of  the body.

 

As an aside, I noticed that Applied Food Sciences is based in Texas.  With all of the universities and labs in America, why did they go to India to test their product?

 

At the end of the study:

• When used for 6 weeks, people lost about 2 kg (about 4 lbs) when taking 1050 mg of green coffee bean extract and about 1.5 kg (about 3 lbs) when using 700 mg of the extract. Both of these were deemed statistically significant (that’s good).

• A decrease in body fat by about 1% as well as Body Mass Index was also seen in both the 1050mg and 700 mg doses. Both values were deemed statistically significant.

 

Update: 3/24/14.  I have always suspected there were problems with this study. In 2014 CBS News reported that this study has been retracted (taken back) because the researchers stated that they could not verify the results of the study. It turned out that researchers in India did the actual data collection in the study -not the researchers whose names appeared on the paper.

 

For more on this controversy, see these links:

• Dr.Oz-endorsed diet pill study was bogus, researchers admit

• Authors retract green coffee bean diet paper touted by Dr. Oz

• How this unproven supplement tricked consumers and made millions

 

In a 2014 study, researchers published  Lipolytic activity of svetol®, a decaffeinated green coffee bean extract. This was a study of human fat cells. Basically fat cells were incubated in green coffee bean extract (the product was Svetol) for between 2 hours and 8 days to see if the extract help release fat stores.

These researchers noted that short term (2 hours) fat loss might be due to “residual caffeine traces” (odd, since Svetol is said to be decaffeinated) and that long term (8 day) fat release was not due to caffeine but rather was attributed to Svetol.

While this is interesting, it is basically just a test tube study. Also, for those who are curious, the lead researcher of this study has an association with a supplement company that makes green coffee extract supplements.

 

Green Coffee and Blood Sugar

Its possible people with diabetes have heard that green coffee supplements might help them reduce blood sugar levels. A test tube study from 2010 did note that the green coffee supplement called Svetol appeared to have blood sugar lowering effects.  A mouse study, published in 2012 also appeared to show improvements in blood sugar control. This study also involved the Sevetol supplement. In a study, involving 60  healthy (non diabetic) women, higher chlorogenic acid (thought to be the active ingredient in green coffee) levels were associated with lower blood sugar.

Supplements Vs. Green Coffee?

I want to point out that supplements are not the only way to obtain the chlorogenic acid.  When I checked Amazon, I saw several brands of green coffee. Yes, you can just drink the coffee if you like.

 

Which Supplement Is Best?

If you have walked through your local vitamin store, you may have noticed that there are a LOT of different green coffee supplements out there. All of the different brands I saw made specific reference to how much chlorogenic acid they had ( 50% for example). While I think they are all pretty much the same, one thing I'd take note of is how many capsuels you need to take to get the amount listed.

For example, if a supplement contains 200 mg of green coffee extract and has 50% chlorogenic acid, do you need to take 1, 2 or 3 capsules to get that amount?  If the recommended amount is 3 capsules and the bottle only has a total of 30 capsules, then that product might only last you 10 days. A product like that would get expensive quickly. Consider this as well as the price when evaluating different supplements.

Some products might also combine green coffee with other ingredients like rhaspberry ketones or garcinia cambogia (or whatever is trendy  when you read this). I recommend not paying extra for supplements that combine green coffee with other ingredients. If the research is to be believed, then green coffee is the only ingredient that should be needed.

See the reviews on rhaspberry ketones and garcinia cambogia for more on those specific products.

 

What Is Svetol?

Svetol has been mentioned a few times in this review so let's briefly discuss what it is. Svetol is a proprietary green coffee supplement made by a French company called Naturex. Their address in the US is 375 Huyler Street South Hackensack NJ 07606. Searching online for this address does indeed show a large white building with the letters “Naturex.” That's good.

As you investigate which supplement might be right for you, you'll notice many of them display Svetol on their lables. My hunch is the the Naturex company licenses Svetol to be used by other companies in their supplements. This is often happens when one participial ingredient has been studied clinically (which Svetol has been).

Because Naturex makes Svetol, all of the different brands of supplements that contain it, should work about the same. This is good news for those who are comparing products. See the section above on “which supplement is best” for more on how to pick product.

 

 

How Much Works?

The 2011 meta analysis of green coffee bean already mentioned, states that ” The effective dosage of GCE (green coffee extract)  for use as a weight loss supplement is also not established.” In other words, if green coffee bean does help weight loss, the amount that works is not known.  Many supplements on the market contain 200 mg. Some of the studies mentioned above have used this amount. I noticed on the Naturex website (the company that makes Svetol), they recommended 400 mg.

 

 

Green Coffee Bean Side Effects

I think green coffee is safe in healthy people. No study that I saw noted any significant side effects. That said here is a list of things to keep in mind. This list is not complete.

•  Always look at the back labels of the weight loss supplements you use to see the list of ingredients they contain. If the research is to be believed, only green coffee bean extract should be needed. Nothing else.
  

• Investigate the companies whose products they use to make sure you are only getting green coffee bean extract. In this 2011 case report, titled Adverse drug reactions of a slimming product contaminated with sibutramine , a green coffee bean supplement was found to be spiked with an illegal weight loss drug called sibutramine. Sibutramine (also known as Meridia) was removed from the US market because it's been linked to heart attacks and strokes.

• Also, as far as I can tell, all the human green coffee studies conducted to date have used “healthy people.” I am not aware of any study that has tested green coffee bean supplements in people with health problems  or who take various medications . To be safe, those with health conditions should speak to their doctor or pharmacist.

• One rat study noted that green coffee extract lowered blood pressure. Whether this applies to people or not needs better research. Those taking medications for high blood pressure should consult their doctor.

• Stop taking green coffee supplements at least 2 weeks before having surgery.

• Speak to your doctor if pregnant or breastfeeding.

• A small study from 2001 published in the American Journal of Clinical Nutrition, noted that high doses (2000 mg) of chlorogenic acid increased homocysteine levels in men and women. While controversial, homocyestine may play a role in heart disease. It is unknown if green coffee bean supplements raise homocysteine. People with heart disease who take green coffee bean supplements should speak to their doctor about their homocysteine levels first, just to be safe.

 

Does Green Coffee Bean Work?

There is no doubt that green coffee bean has some weight loss research. There is also no doubt that the weight loss proof is a lot less than what most would have you believe. Currently most of the evidence for green coffee stems from lab animal research, test tube studies and human studies that dont have many people.  For those who are curious, as far as I could tell, the product called Svetol, appears to be one of the few  supplement's that had at least some human clinical evidence.  While I remain somewhat skeptical, if the human weight loss research conducted so far are to believed, green coffee bean might help people lose a little weight, but until better research is conducted, it's hard to say for sure.

What do you think?