Throughout my career, I’ve seen dozens of “hot” weight-loss supplements come and go, including bitter orange, chromium picolinate, CLA, hoodia, yerba mate, raspberry ketones, and now green coffee bean extract. Each has been touted as an effortless way to shed pounds, by either boosting metabolism, mobilizing body fat, or suppressing appetite. But as a health professional, it’s my job to be skeptical and ask the tough questions, such as does it really work, where’s the proof, and, above all, is it safe?
You may have seen green coffee extract at Starbucks, promoted as a natural energy source with no coffee flavor. It was also featured recently on The Dr. Oz Show. On his program, the doc revealed the results of his own investigation, which involved recruiting 100 women who either received a placebo or a 400 mg green coffee bean supplement. The ladies were instructed to make no changes to their diets, and after two weeks, those who had popped the green coffee bean extract lost an average of two pounds, compared to one pound for the placebo group. Interesting, but I’m not ready to recommend it yet. Here’s the nitty-gritty:
What is green coffee extract?
Coffee beans are actually green seeds inside a bright red berry. Roasting them turns the seeds brown and creates the characteristic aroma and flavor coffee lovers crave. To create green coffee bean extract, the seeds are left unroasted. Instead they’re soaked and then concentrated to create the extract.
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Why not just drink coffee?
When coffee seeds or “beans” are roasted, their antioxidant levels increase, but one natural substance called chlorogenic acid decreases. This chemical is thought to block fat accumulation, boost weight loss, curb carb absorption, and help regulate post-meal blood sugar levels. In addition, green coffee extract does not taste or smell like coffee, a supposed benefit for those who don’t enjoy java.
Does it work?
Honestly, the evidence is pretty scant. One 2012 study made a big splash when it found that subjects who consumed 1,050-mg and 700-mg doses lost about 16 pounds in six weeks compared to a placebo group. However, the study was criticized because it involved such a small number of subjects—only 16—and it was funded by a green coffee bean extract manufacturer. An independent analysis of three randomized clinical trials that included a total of 142 participants concluded that the effect of green coffee extract is only moderate at best, and the studies were poorly conducted.
Is it safe?
For me this is the million-dollar question because even if something “works” for weight loss, it’s not worthwhile if it creates other unwanted side effects. In this case the answer is: It depends.
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Unfortunately there is no standardization when it comes to supplements. In other words, manufacturers don’t have to follow a specific formula, so one green coffee extract product could be made completely differently than another, and one brand could contain significantly more caffeine than the bottle next to it. That concerns me because concentrated doses of caffeine can cause headaches, GI upset, nervousness, insomnia, anxiety, ringing in the ears, and irregular heart beat, or even more serious problems in some people. In addition, using caffeine-based weight-loss supplements and then stopping them has also been associated with withdrawal symptoms including headache, fatigue, depression, trouble concentrating, nervousness, muscle tension, and a flushed face.
Finally, caffeine-based supplements can react with other supplements. For example, taking one with another stimulant (like guarana or mate) can trigger a synergistic effect that could increase blood pressure to dangerous levels. A high caffeine intake can also trigger the loss of calcium and magnesium. And there’s a long list of prescription medications that interact with caffeine, from diabetes and blood pressure drugs to meds used for depression.
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After reviewing the research as well as the risks, it seems like the cons outweigh the pros here, at least for now. And at about $20 per 30-day supply, you could invest in other weight-loss strategies that get my thumbs up, such as taking a fun fitness class or buying more fresh fruits and veggies!
Cynthia Sass is a registered dietitian with master's degrees in both nutrition science and public health. Frequently seen on national TV, she's a SHAPE contributing editor and nutrition consultant to the New York Rangers and Tampa Bay Rays. Her latest New York Times best seller is S.A.S.S! Yourself Slim: Conquer Cravings, Drop Pounds and Lose Inches.