Green coffee beans, or the extract has minimal effects on body weight (see meta-analysis results below). Additionally, results from studies on green coffee extract and weight loss pale in comparison to research using the ingredients found in the dotFIT weight loss products, and especially when compared to the proper use of meal replacements (see below for comparisons). With all due respect to the television doctor, Dr. Oz, current scientific consensus at this time is that GCE alone is not recommended for weight loss.
Green coffee extract (green coffee simply refers to the raw coffee beans, which have a green color) may have health benefits just as roasted coffee has demonstrated over the years, including reducing the risk of diabetes, gallstones, Parkinson's disease, etc. Also keep in mind that caffeine itself is associated with increased weight loss. Green Coffee Extract (GCE) is especially rich in chlorogenic acid, a polyphenol that has shown in animal and lab studies to have an antioxidant and anti-inflammatory properties as well as positive effects on blood sugar and body weight. Roasting of coffee destroys most of the compound, but roasted coffee beans have other beneficial effects that green coffee lacks. The few studies that show people losing more weight with GCE versus placebo only demonstrated a minor difference with probably no clinical significance in the long-term. Below is a review of the only 3 studies that had few enough flaws to be considered. As you will see from the results and conclusion there is little value from GCE alone.
GCE Study Results
Approximately 5 lbs lost over 12 weeks versus placebo but further review found 2 of the 3 studies showed no significant weight loss (see "Results" in study text below).
The Use of Green Coffee Extract as a Weight Loss Supplement: A Systematic Review and Meta-Analysis of Randomised Clinical Trials
Gastroenterol Res Pract. 2011; 2011: 382852. Published online 2010 August 31
Abstract
The purpose of this paper is to assess the efficacy of green coffee extract (GCE) as a weight loss supplement, using data from human clinical trials. Electronic and non-electronic searches were conducted to identify relevant articles, with no restrictions in time or language. Two independent reviewers extracted the data and assessed the methodological quality of included studies. Five eligible trials were identified, and three of these were included. All studies were associated with a high risk of bias. The meta-analytic result reveals a significant difference in body weight in GCE compared with placebo (mean difference: −2.47 kg; 95%CI: −4.23, −0.72). The magnitude of the effect is moderate, and there is significant heterogeneity amongst the studies. It is concluded that the results from these trials are promising, but the studies are all of poor methodological quality. More rigorous trials are needed to assess the usefulness of GCE as a weight loss tool.
Results
The meta-analysis reveals a statistically significant difference in body weight between GCE and placebo (MD: −2.47 kg; 95% CI: −4.23, −0.72). The I2 statistic of 97% suggests that there is considerable heterogeneity amongst the studies. A further plot of two trials which involved CGA-enriched GCE revealed a statistically non-significant difference in body weight between GCE and placebo (MD: −1.92 kg; 95% CI: −5.40, 1.56). Heterogeneity was also considerable in this analysis (I2 statistic of 99%). One of the studies reported a statistically significant decrease in the percentage of body fat in the GCE group compared with baseline, but no significant difference in the placebo group. There was no mention of intergroup differences regarding the percentage of body fat. None of the trials reported any adverse events associated with the use of GCE.
Conclusion
The evidence from RCTs seems to indicate that the intake of GCE can promote weight loss. However, several caveats exist. The size of the effect is small, and the clinical relevance of this effect is uncertain. More rigorous trials with longer duration are needed to assess the efficacy and safety of GCE as a weight loss supplement.