Green coffee extract has been hailed as a “miracle” supplement for weight loss, but research into these claims shows that miracles don’t come in pill form.
New research from the American Chemical Society into chlorogenic acid (CGA)—a main ingredient in green coffee supplements—shows that it doesn’t support weight loss and can actually cause fatty deposits to accumulate in the livers of mice.
Prior studies have shown that coffee drinkers have a lower risk of a collection of disorders known as “metabolic syndrome”: obesity, high blood pressure, and insulin resistance.
Researchers tested the effects of high doses of CGA to see if it decreased symptoms of metabolic syndrome in genetically engineered mice. The mice were kept on either a normal diet, a high-fat diet, or a high-fat diet supplemented with CGA.
After 12 weeks, the mice consuming CGA not only didn’t lose weight compared to the other mice on the high-fat diet, but the CGA mice had increased insulin resistance and higher fat content in their livers.
“This study suggests that CGA supplementation in a high-fat diet does not protect against features of metabolic syndrome in diet-induced obese mice,” the researchers concluded in their study, published this week in the Journal of Agricultural and Food Chemistry.
A Dr. Oz ‘Miracle’ That’s Short on Evidence
One of the biggest proponents of green coffee extract for weight loss has been celebrity doctor Mehmet Oz.
“Magic is make-believe, but this little bean has scientists saying they’ve found a magic weight loss cure for everybody,” Dr. Oz said on his show in 2012. “It’s green coffee beans, and when turned into a supplement, this miracle pill can burn fat fast.”
Dr. Oz cited a study that tied green coffee to weight loss, asserting that people who took it lost an average of 18 pounds in six weeks. One major problem with that study, published in the journal Diabetes, Metabolic Syndrome and Obesity, was that it involved only 16 subjects.
The Dr. Oz Show's episode on green coffee featured certified nutritionist Lindsey Duncan. The show failed to disclose Duncan’s conflict of interest: He’s also the chairman and CEO of Genesis Pure, a supplement company that sells, among other things, the same green coffee bean supplement Dr. Oz called a “miracle pill.”
On a follow-up program months later, Dr. Oz said sales of the bean had soared and that he himself had been accused of profiteering. He responded that he made no money from the supplement's endorsement.
To test the effects of green coffee extract, Dr. Oz’s medical team then did their own blind study to test the pill’s effectiveness for weight loss in nearly 100 women ages 35 to 49 with a body mass index (BMI) between 25 and 45. During the testing period, 50 women took a 400mg green coffee pill three times a day, 30 minutes before meals, and also kept a log of the food they ate.
At the end the two-week experiment, the 50 women tested lost an average of 2 pounds, while the 50 women given placebos lost and average of 1 pound. Dr. Oz deemed the pills “a safe way for you to sustainably lose the weight.”
“The bottom line, and I’m going to say it here, green coffee bean worked for us,” he concluded, though he added that keeping a food journal “doubles your weight loss.”
Despite his far reaching claims earlier—bolstered by an expert with a financial stake in the supplement business—Dr. Oz’s own experiments on the effectiveness of green coffee extract fell short of dramatic weight loss results. Yet he still recommended green coffee extract with a minimum of 45 percent chlorogenic acid to a national audience, despite admitting “we don’t know much about it.”
Requests for comment from The Dr. Oz Show were not returned Friday.
How to Really Lose Weight
While it would be nice to be able to eat whatever you’d like and take a pill—without side effects—to maintain an ideal weight, no pill can yet make the human body do that safely.
A diet rich in fresh fruits and vegetables and whole grains but low in processed foods and fats has been proven to help the body ward off disease, and along with regular cardiovascular exercise, it can be an effective way to keep a healthy weight.
True weight loss—the kind that keeps the weight off—involves discipline through diet and exercise.