Effect of Green Coffee Supplementation on Weight Loss and Weight-Related Parameters: A Systematic Review of Clinical Trials

 Obesity is an excessive amount of energy stored in a form of fat in body, which is a serious medical, social, and economic problem. The factors affecting obesity include geographic location, environment, genetic effects, energy imbalance, inappropriate diet, and physical inactivity. It has been shown that green coffee extract can affect weight by changing plasma adiponectin levels, distributing body fat, and decreasing the concentration of fatty acids. This study aimed to summarize the data from clinical and laboratory trials related to the effect of green coffee supplementation on weight and parameters associated with obesity.  To conduct the study, the articles published between 1990 and 2018 related to the effect of green coffee supplement on weight loss were searched in PubMed, Scopus, ISI, and Google Scholar databases. The search process was accomplished using the keywords of Green Coffee, Green Coffee Extract, Roasted Coffee, Decaffeinated Coffee, Chloronergic Acid, Obesity, Overweight, Body Fat Percent, BMI, Abdominal Fat, Antiobesity Agent, Weight Loss, Weight Decrease, Weight Gain, and Weight Control.  The exact mechanism of green coffee extract in weight loss, BMI, and body fat percentage is still unknown. The findings suggest that chlorogenic acid plays a major role in weight changes due to its various antioxidant properties and its effect on anti-inflammatory factors, which can be manifested by a reduction in weight loss, BMI, or other parameters. Some studies have also shown the effects of green coffee bean extract on the changes in liver PPAR expression.  Green coffee can affect lipid and glucose metabolism, which includes reduction of serum insulin as a result of a reduction in glucose uptake, inhibition of glucose 6 phosphatase activity, as well as suppression of lipid absorption, decrease of lipogenesis, and increase of lipolysis. These changes lead to weight loss, reduced fat percentage, and decreased BMI.