Green Coffee Extract as a Weight-Loss Aid: the Facts

Green Coffee

The weight loss industry has seen its fair share of short-cut laden fads, promising results after minimal effort. These marketing tactics often work—raspberry ketone product sales, for example, grew by triple digits in 2013, a year after they first received national attention on the Dr. Oz show. These health-centric short cuts are welcome news to consumers; after all, why test will power, expend extra effort, and waste time for minimal gains when you could spend your time otherwise? The appeal is evident. A solid scientific basis on which those claims are made, however, is often not. To that point, raspberry ketones still lack conclusive scientific evidence of any weight loss benefits. What about Green Coffee Extract (GCE), a coffee bean-based supplement that has also recently garnered consumer attention for its weight loss-enhancing claims?

An Introduction

Typically, the seeds (beans) of the Coffea fruit are roasted to become the source of our coveted morning ritual, coffee. However, while exposure to the high heat of roasting gives coffee beans their unmistakable flavors and scents, it also chemically reduces a compound called chlorogenic acid—the active ingredient suggested to be responsible for most of GCE’s health claims. It is generally thought that chlorogenic acid content is the primary chemical difference between the coffee beans’ roasted and raw varieties.


GCE has enjoyed the spotlight in recent years primarily due to its claim as a highly effective weight-loss aid. Popular on-screen personality Dr. Oz has previously said that GCE is “one of the most important discoveries we’ve made to help you burn fat faster.” Advertising at its finest?

Is There Any Scientific Evidence Supporting GCE’s Claims?

A 2006 study assessed the effects of GCE on both fat absorption and triglyceride metabolism—measures used to describe fat accumulation and body-weight gain—in mice pre-fed with olive oil. The results indicated that GCE reduced visceral fat content (a subclass of fats that envelopes organs; thought to be particularly detrimental to human health) as well as overall body weight. Researcher concluded that GCE was “possibly effective” against weight-gain by both inhibiting fat absorption and priming the liver for fat metabolism. The weight-loss properties of GCE were a team effort; the study suggested that caffeine was responsible for suppressing fat absorption, chlorogenic acid reduced triglyceride accumulation in the liver, and a metabolite of chlorogenic acid, ferulic acid, increased the liver’s metabolic activity.

Although animal studies do not definitively predict human response, they do lend legitimacy to the possibility of similar effects in humans. Despite the popularity of GCE as a weight-loss supplement, few human trials have been conducted. According to a 2011 meta-analysis, only 5 trials using GCE have been conducted, 3 of which used weight as their primary objective. However, study authors note that these trials were short-term and may have been subject to bias and a high degree of heterogeneity, diminishing the validity of their claims. Furthermore, two of them were associated with for-profit organizations—a clear conflict of interest.

In one of the higher quality clinical studies, researchers found that chlorogenic acid-enriched instant coffee was able to significantly reduce the absorption of glucose compared to controls. In continuation, the researchers conducted a second, randomized, double-blind study to assess the effects of chlorogenic acid on body mass. In this 12-week study of 30 overweight individuals, researchers found that those in the chlorogenic acid-enriched coffee group lost an average of 5.4kg while those consuming regular instant coffee lost only 1.7kg. Authors concluded that chlorogenic acid “appears to have a significant effect on the absorption and utilization of glucose.”

Considerations & Final Thoughts

In the limited number of studies available, the science suggests that GCE may support minor weight loss, but only in overweight subjects. No studies have yet been conducted in lean individuals. Furthermore, the majority of available studies are tainted by lackluster experiment design and conflicts of interest.

Also, remember that GCE still comes from the coffee plant—so it may have high levels of caffeine. If you’re used to drinking a few cups of joe every day, taking GCE may add to your tally. Excess caffeine has been linked to irritability, nervousness, restlessness, and insomnia, among others.

Overall, while the research is promising, it is by no means definitive. Larger, higher quality trials will be needed to accurately assess the effects of GCE on weight loss. With that said, any claimed quick and easy fixes to what we know are hard, long-term self-improvement projects are probably not worth your cash—at least, until more conclusive data comes rolling in.