Green Coffee Bean Extract for Weight Loss?

Green Coffee Bean Extract for Weight Loss?

For those of you who’re interested in shedding a few pounds, particularly the under chin fat–whether your motivation comes from wanting to improve your overall health or simply look better at the beach this summer, the coffee bean just keeps giving and giving…

Previously, I wrote about how coffee mannans (coffee mannooligosaccharides) which are basically an indigestible component found in coffee beans helped men but not women lose a modest amount of weight.

green coffee bean

More recently, researchers from the chemistry department at the University of Scranton have looked at the weight loss benefits associated with supplementation with green coffee bean extract [1].  Specifically, the product, GCA® was provided by Applied Food Sciences Inc (Austin, TX).  The study authors did not disclose any conflicts of interest and apparently did not seem to indicate that this manufacture paid for the study itself.


Study Design:

The researchers utilized a randomized, double-blind, placebo-controlled, linear dose, crossover design to evaluate the safety and efficacy of Green Coffee Bean extract at promoting weight loss in overweight subjects.

The study was only modestly powered with a total of 16 subjects included.

Green Coffee Bean Extract

The supplement was provided by the aforementioned manufacturer in Austin TX.  Two dosages (1050 mg, 700 mg) were compared with placebo.  Each dosage was taken for a duration of six weeks with a two-week washout period in between.

Did it work?

The results of this particular study if replicated in subsequent trials are pretty staggering:

Significant reductions were observed in body weight (−8.04 ± 2.31 kg), body mass index (−2.92 ± 0.85 kg/m2), and percent body fat (−4.44% ± 2.00%), as well as a small decrease in heart rate (−2.56 ± 2.85 beats per minute), but with no significant changes to diet over the course of the study. Importantly, the decreases occurred when subjects were taking GCA. Body mass index for six subjects shifted from preobesity to the normal weight range (<25.00 kg/m2).

Note that these numbers are from baseline to the end of the 22 week study.  Overall, there was roughly a net 10% reduction in both body weight and BMI with a 15.8% reduction in body fat.

What’s somewhat interesting is that if you look at the weight loss data (figure 1), the group that started with placebo appears to have lost most of its weight during this phase.

Though the authors did not report any side effects from GCA extract nor any participants withdrawing from the study, there was a non-statistically significant increase in blood pressure of just under 5 mmhg from the beginning to the end of the trial (table 1).

The authors noted in their discussion:

“Attrition rates averaged 30%–40%. Compared with placebo, orlistat reduced weight by 2.9 kg (2.9%) sibutramine by 4.2 kg (4.3%), and rimonabant by 4.7 kg (4.1%). BMI reductions were 1.0 with orlistat and 1.5 with sibutramine. Lack of adherence to treatment seems to be a major factor limiting the efficacy and effectiveness of antiobesity drugs.(ref) Thus the GCA with a weight loss of 8 kg (10.5%) and a BMI reduction of almost 3 makes the product superior to the prescription drugs.”

Granted that these claims seem a little extravagant given the number of participants included in this study (16), these initial findings suggest that Green Coffee Bean extract could be a very promising weight loss supplement.

Though it’s not currently understood how GCA extract promotes weight loss, the study authors speculated that one component, chlorogenic acid, may alter glucose absorption or possibly activate fat metabolism.


  1. Vinson JA, Burnham BR, Nagendran MV.  Randomized, double-blind, placebo-controlled, linear dose, crossover study to evaluate the efficacy and safety of a green coffee bean extract in overweight subjects.  Diabetes Metab Syndr Obes. 2012;5:21-7. Epub 2012 Jan 18.

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