Lately, you may notice ads reading "Take Green Coffee for Weight Loss!" following you all over the internet—I know I have. These ads are selling green coffee bean extract, a supplement that has been shown in some limited studies to promote weight loss. These ads often reference Dr. Oz, because he's discussed the product on his show and website and conducted a small experiment in which women who took green coffee extract lost slightly more weight than those taking a placebo.
There is some evidence that green coffee leads to weight loss by inhibiting an enzyme called hepatic glucose-6-phosphatase, thereby reducing glucose levels and leading the body to use fats for energy instead of glucose.
But if you decide to try taking green coffee for weight loss, know that not all supplements are equally effective: independent tester ConsumerLab recently analyzed eight brands of green coffee bean extract to see if they contained adequate amounts of the key ingredients (chlorogenic acids) shown to work in clinical studies. They found that four did not contain enough of this ingredient, and one brand contained none at all!
They also compared the products' prices to learn which are the best value. ConsumerLab found one brand of green coffee extract to have effective levels of key ingredients and a low price per dose: Vitacost Green Coffee Bean Extract 400 mg Capsules, which cost twenty cents per dose.
The ConsumerLab reviews of green coffee bean extract can be found here (there is a fee to view the full report).
More about the health effects of coffee: