Green coffee beans are coffee beans that have not yet been roasted - they are simply beans straight from the plant. The roasting process reduces amounts of a constituent chemical called chlorogenic acid (in fact it comprises 50% of the coffee bean). Coffee is roasted because the chlorogenic acid is extremely bitter and therefore not a desired taste in drinking coffee.
The key ingredient and its role in weight loss
Chlorogenic acid in green coffee is thought to affect how the body handles blood sugar and metabolism and has been linked to weight loss. It has been claimed that when you take green coffee bean extract it signals your body to burn fat for energy more readily. Furthermore it said to inhibit the release of glucose in the body, in other words it blocks sugar you consume from entering your bloodstream - this means your body doesn't get the chance to use that sugar to build more fat storages.
Initial study shows staggering results
Green Coffee Bean extract had a surge in popularly for weight loss after it was mentioned on the Dr. Oz show in 2012. The Dr. Oz show referred to it as “The green coffee bean that burns fat fast” and claimed that no exercise or calorie restricted diet is needed. He had read a study published in the journal Diabetes, Metabolic Syndrome and Obesity, involving sixteen adults over the course of 12 weeks which claimed that a particular brand of green coffee bean extract called GCA led to significant weight loss. The results showed subjects dropped an average of seventeen pounds, resulting in a 16% reduction of their fat (10% of their overall body weight and 4.4% of their overall body fat).
These are good results on the face of it but it's worth noting that this study involved only 16 people, this is a tiny sample. There was also no proper placebo control - this makes it impossible to tell how much weight loss can be attributed to the green coffee beans versus the daily monitoring and logging of food intake, which is known to help with weight loss.
Further studies show positive results
Dr. Oz was prompted to conduct a study of his own into the effectiveness of Green Coffee Bean Extract in weight loss. The study selected 100 women who fell between the following criteria:
- Between the ages of 35 and 49
- Were overweight with BMIs between 25 and 45
- Had no major medical problems (e.g. diabetes, history of heart attack or stroke)
- Weren’t pregnant or breastfeeding
The women were then given either a placebo or Green Coffee Bean Extract (they didn’t know which they were given i.e. double-blind study) and told not to change their diet or exercise routine in any way. They were given 400mg capsules 3 times a day 30 minutes before each meal. They also had to keep a food diary (a log of the food they ate). After two weeks, the 50 women given the Green Coffee Bean Extract lost an average of 2 pounds while the 50 woman given the placebo lost an average of 1 pound.
Dr Oz concluded that the pills were a safe way to lose weight sustainably - but inferred that more research was needed, admitting that keeping a food diary "doubles your weight loss". It is also worth noting that the study was held over a period of just 2 weeks, which is a very short time frame in which to assess a weight loss treatment.