Sales of green coffee bean extract soared after Dr. Oz’s eyes twinkled with excitement as he exclaimed, “It burns fat fast” to millions of viewers waiting on the edge of their seats, grasping their hands, hopeful that scientists finally found a natural cure for their weight-loss woes. Even the most skeptical consumers seemed convinced after Dr. Oz highlighted the results of his own little experiment— overweight women taking green coffee bean extract lost twice as much weight over a two-week period compared to those given a placebo.
What Are Green Coffee Beans?
Green coffee beans are unroasted beans, technically seeds, from the coffee plant. They are transformed into brown beans with their characteristic rich aroma and bold flavor when roasted at very high temperatures of about 550 degrees Fahrenheit. Once they reach an internal temperature of approximately 400 degrees Fahrenheit, their color transforms from green to brown and the oil from inside seeps out, coating the beans with a glossy sheen. Green coffee bean extract is extracted from green (raw) coffee beans and sold in weight-loss supplements.
Though the only difference separating green and brown coffee beans is the roasting process, high heat destroys the active compounds naturally found in coffee beans that are responsible for enhancing weight loss— chlorogenic acids (CGAs). CGAs are a group of 71 antioxidant compounds with antibacterial and anti-inflammatory actions. And though other plants contain CGAs, including apples, pears, tomatoes, carrots, sweet potatoes, cherries and eggplant, coffee contains the highest amount found in plants. Brown coffee beans contain significantly smaller quantities of these antioxidants and when beans are roasted for 11 minutes or more, only trace amounts of CGA are detectable, making raw green coffee beans the clear front-runner.
In addition to CGAs, all coffee beans are natural sources of the stimulant caffeine. Caffeine can improve mental focus, enhance alertness and independently mobilize fat stores so your body can use them for energy. However, if you don’t actually need the energy, let’s say you are drinking your morning cup o’ Joe while checking e-mail, your fat will go right back to where it was sitting on your body, making caffeine-induced mobilization of fat like a joy ride to no where. But, caffeine is dependent on what you pair it with. Take caffeine about 30 to 45 minutes before your high-intensity interval training session and your body will probably use some of that mobilized fat to fuel your activity. Likewise, caffeine is also more effective when paired with certain antioxidant compounds like CGAs. Consider it a team approach to fat loss.
Preliminary research in animals shows green coffee bean extract works via multiple mechanisms to improve health by increasing fat metabolism in the liver, decreasing cholesterol and triglycerides, decreasing bodyweight and visceral fat and improving the body’s ability to handle circulating blood sugar. Subsequent studies in humans show green coffee bean extract may lead to a smidgen of weight loss. Yet only a few studies to date have used the goal standard a randomized, double-blind placebo-controlled design. And, a thorough look through the literature resulting in a systematic review and meta-analysis published in 2011 found just three studies that used this design to examine the effects of green coffee bean extract in overweight and obese humans. This meta-analysis concluded that CGA enriched green coffee and green coffee bean extract helped overweight and obese adults lose a significant amount of weight and fat over a four- to 12-week period, whereas groups taking a placebo experienced no change in weight.
However, study authors cautioned that the results were moderate and all three studies didn’t provide any details regarding how the study subjects were randomized into groups or if the scientists assessing the results knew which group received the supplement and which was given the placebo. These factors alone could have biased the results and, if a study actually used a completely unbiased study design, they would probably provide every single detail in their journal article. Compounding the meta-analysis even more— when they examined the two studies that used CGA-enriched green coffee, there were no statistical significance differences in weight loss between the green coffee bean extract and placebo groups. Something is a little sketchy here.
What about the exciting results from the Dr. Oz trial where the women randomly assigned to the green coffee bean extract group lost twice the amount of weight as the placebo group? In this instance, “twice” equated to one pound. The placebo group lost one pound over the two-week period, whereas the group taking 400 milligrams of green coffee bean extract three times a day, 30 minutes before their meals, lost two pounds. Is that a statistically significant difference? No one knows, since Dr. Oz’s experiment wasn’t published and therefore put through the rigors of statistical analysis. And, all of the women in his study kept a food journal. Despite the fact that they didn’t follow a diet, food journaling inherently changes behavior by increasing awareness of one’s food intake. Plus, journaling is free. Green coffee bean extract is starting to sound like one more expensive weight-loss hoax than the light at the end of the weight-loss tunnel.
Despite the looming questions on this “miracle” supplement, a seemingly well-designed 2012 study found CGA is a promising weight-loss aid. In this randomized, double-blind, placebo-controlled study, both low-dose (700 mg taken in two separate doses of 350 mg during the day) and high-dose (1,050 mg taken in three separate doses of 350 mg during the day) CGA supplements promoted significant reductions in weight, BMI and percent body fat in overweight adults over the six-week period, while the placebo periods led to no changes.
Yet the results of this study— the one that Dr. Oz reported about on TV— were completely bogus. The company behind the study, Applied Food Sciences, paid researchers in India to conduct the study and the study authors manipulated the data, including reported weights, so CGA appeared to help consumers lose weight. When the Federal Trade Commission, a group that works to protect consumers from deceptive, fraudulent and unfair business practices, got involved, they found the study was so flawed that “no reliable conclusions could be drawn from it.” As a result, the Federal Trade Commission is requiring Applied Food Sciences to pay $3.5 million and provide scientific substantiation for any weight-loss claims they make in the future. The study authors retracted their published article.
Is It Safe?
Green coffee bean extract is considered safe in moderate doses— no adverse events have been reported from human trials. However, more recently, 12 weeks of CGA supplementation in mice resulted in insulin resistance, a precursor to diabetes, and a fatty liver. Granted, mice aren’t humans, the risks of obesity alone are crystal clear and other popular methods of weight loss, including prescription drugs and weight-loss surgeries come with a multitude of potential, and serious, adverse effects. However, it’s always important to keep in mind that no supplement comes with a guaranteed stamp of safety and it is possible that green coffee bean extract supplements may interact with medications and over-the-counter drugs.
In addition, always consider the caffeine content of a supplement. Know your caffeine limit, since too much can lead to increased anxiety, nervousness, headaches, abnormal heart rhythms and difficulty sleeping. And, anyone who is pregnant, ill, has heart disease or is on any prescription medication should consult her physician prior to increasing her caffeine intake or trying a new supplement. Take a close look at any supplement you pick up— some contain many ingredients including several stimulants (not just caffeine).
Before considering green coffee bean extract or a CGA supplement, consider the cost, questionable data and safety concerns. Obesity and being overweight are clear risk factors for several chronic diseases. And, even modest reductions in visceral fat, the kind that lies deep inside your stomach, covering your organs like a pad, can improve insulin sensitivity, blood cholesterol, triglycerides and inflammatory markers while improving fitness. However, at this time it is highly doubtful that green coffee bean extract or CGA-enhanced supplements will help you lose a significant amount of body fat. And therefore, you are better off following proven methods for shedding excess fat— changing your diet and ramping up your exercise program.
Després JP, Lemieux I, Tchernof A, Couillard C, Pascot A, Lemieux S. Fat distribution and metabolism. Diabetes Metab 2001;27(2 Pt 2):209-14.
Borel AL, Nazare JA, Smith J, Alméras N, Tremblay A, Bergeron J, Poirier P, Després JP. Visceral and not subcutaneous abdominal adiposity reduction drives the benefits of a 1-year lifestyle modification program. Obesity (Silver Spring) 2012;20(6):1223-33.
Dulloo AG. The search for compounds that stimulate thermogenesis in obesity management: from pharmaceuticals to functional food ingredients. Obesity Reviews 2011;12;856-883.
Dulloo AG, Geissler C, Horton T, Collins A, Miller DS. Normal caffeine consumption: influence on thermogenesis and daily energy expenditure in lean and post-obese human volunteers. Am J Clin Nutr 1989;49:44-50.
Farah A, De Paulis T, Trugo LC, Martin PR. Effect of Roasting on the Formation of Chlorogenic Acid Lactones in Coffee. J Agric Food Chem 2005;53:1505-1513.
Upadhyay R, Mohan Rao LJ. An outlook on chlorogenic acids-occurrence, chemistry, technology, and biological activities. Crit Rev Food Sci Nutr 2013;53(9):968-84.
Ten steps to coffee. National Coffee Association. Website: http://www.ncausa.org/i4a/pages/index.cfm?pageid=69
Almeida AA, Farah A, Silva DAM, Nunam EA, Glória MBA. Antibacterial activity of coffee bean extracts and selected coffee chemical compounds against enterobacteria. J Agric Food Chem 2006;54:8738–43.
Santos MD, Almeida MC, Lopes NP, Souza GEP. Evaluation of the antiinflamatory, analgesic and antypiretic activity of the natural polyphenol chlorogenic acid. Biol Pharm Bull 2006;29:2236–40.
Igho Onakpoya, Rohini Terry, and Edzard Ernst, “The Use of Green Coffee Extract as a Weight Loss Supplement: A Systematic Review and Meta-Analysis of Randomised Clinical Trials,” Gastroenterology Research and Practice, vol. 2011, Article ID 382852, 6 pages, 2011. doi:10.1155/2011/382852
Quick M, Kiefer D. Weighing in: green coffee bean extract – a potential safe and effective weight loss supplement? Integrative Medicine Alert 2013;16:97-102.
Caffeine. Medline Plus. http://www.nlm.nih.gov/medlineplus/caffeine.html
Aidilla M, Hodgson JM, Considine MJ, Croft KD, Matthews VB. Supplementation of a High-Fat Diet with
Chlorogenic Acid Is Associated with Insulin Resistance and Hepatic Lipid Accumulation in Mice. J Agric
Food Chem 2013;61:4371–4378.
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: 21–27.