Green coffee bean extract for weight loss
The rate of obesity has more than doubled since 1980, and one in three American adults has a body mass index (BMI) more than 30 kg/m2, according to the World Health Organization. Obesity has been linked to many chronic diseases, including sleep apnea, and is a leading cause of preventable death.
Due to the health risks and social pressures associated with obesity, consumers are interested in new diets, exercise regimens, and weight loss products. Although FDA has approved two prescription drugs for weight loss, many patients have concerns about their adverse effects and prefer natural ingredients. Weight loss supplements often contain ingredients such as green tea extract, açai berry, raspberry ketone, white kidney bean extract, and sea weed. Some of these products also include caffeine, guarana, and weak diuretics.
Green coffee bean extract (GCE) has been widely promoted for weight loss recently. Green coffee beans are unroasted and contain higher concentrations of chlorogenic acid (CGA) than a cup of coffee. This ingredient is theorized to promote fat metabolism and inhibit glucose absorption.
CGA may promote glucose absorption from the distal, rather than proximal, portion of the gastrointestinal tract, leading to decreased caloric intake. Animal research has suggested that CGA may decrease intestinal fat absorption and activate fat metabolism in the liver. Other potential effects include improved lipid profiles, reduction in hepatic lipase, and increased expression of peroxisome receptors which are key modulators of lipids and glucose, indicating potential use in prevention of diabetes. GCE may also possess both in vitro and in vivo antioxidant activity.
Examining the data
In a double-blind, placebo-controlled, 22-week crossover study published online last January in Diabetes, Metabolic Syndrome, and Obesity: Targets and Therapy, 16 overweight adults (average BMI 28.22 kg/m2) were randomized to high-dose GCE (350 mg GCA three times a day), low-dose GCE (350 mg GCA twice daily), or placebo. The treatment period was 6 weeks with a 2-week washout period between each arm of the trial.
Patients who received both GCE dosages reported significant changes in body weight, BMI, and percentage of body fat. Overall, patients lost 8 kg; 10 lost at least 10% of their body weight, and 5 of the remaining 6 subjects lost at least 5%. Researchers had not observed a similar benefit in prior studies, potentially due to the lower daily dosage usually used (180–200 mg). Due to headaches and urinary tract infections, two participants dropped out of the trial.
In a meta-analysis of three randomized controlled trials, not including the above study, published online in Gastroenterology Research and Practice on August 31, 2010, researchers analyzed results from a total of 142 overweight patients and found a trend favoring GCE over placebo for weight loss. Two of the three trials included CGA-enriched green coffee, while the third used GCE. The researchers noted that the best results were obtained when patients exercised as well.
What to tell patients
If patients inquire about GCE, recommend that they use a product produced in the United States that contains at least 45% CGA, is low in caffeine, and is standardized to at least 400 mg per capsule. Tell patients that researchers have not yet established a standard dosage of GCE. In controlled trials, researchers have used the product Svetol at a 400-mg dosage. Advise patients to avoid proprietary blends, as they do not list exact amounts of ingredients.
Caution patients that most studies assessing GCE were conducted in Japan, India, and other countries whose residents have different diets than the average American. In addition, Svetol is expensive, and patients who have a chronic disease, especially hypertension, should avoid use. Last, advise patients that the long-term effects of GCE are unknown.