Update 3/10/20. 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).
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.
Foods that naturally contain chlorogenic acid include:
- 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 the 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 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 able to reduce reducing body weight gain or fat accumulation in the belly.
In another study researchers compared different types of coffee in 30 healthy, normal-weight people. The study lasted 3 months (12 weeks).
The supplement they used was called Svetol
People drank 5 cups of Slender Coffee – or regular coffee – per day for 3 months.
Results: People drinking Slender Coffee lose about 12 pounds compared to placebo coffee (compared to 3.5 pounds with the placebo coffee).
In addition, those drinking Slender coffee people lost more body fat, but body fat was measured using bio-electric impedance which might not be as reliable as other methods.
In another study which looked at 3 previous investigations 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). 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?
- 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: 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:
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.
What Is Svetol?
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. This is the only green coffee bean supplement Ive seen research on. While I remain skeptical of green coffee, if you're looking for a dietary supplement, I'd go with the one with the research.
How Much Works?
I dont think theres enough human research. Most supplements have 200-400 mg per 1 or 2 capsules. some studies have used this dosage too.
Green Coffee Bean Side Effects
Studies generally don't report any serious side effects but here are some things to think about if you try this supplement. This list is not complete.
- Start with less for the first week
- 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 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 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 the weight loss proof is a lot less than what most would have you believe. Most f the research involves lab animals. If your going to try it the supplement that has been clinically studied is called Svetol. That said I remain skeptical.
What do you think?