I rarely recommend nutritional supplements specifically to boost weight loss, as I prefer to concentrate on encouraging good dietary habits first and foremost. However, a new study on green coffee extract did pique my interest. The study suggests that green coffee extract may be an effective supplement in aiding weight loss (1).
This supplement was linked with substantial weight loss, decreased body fat, and a decrease in blood pressure over the short study period.
The research, published in the journal Diabetes, Metabolic Syndrome and Obesity, followed a group of 16 adults over a course of 22 weeks.
Each participant was overweight or obese, and aged between 22 and 26 years. The study used a high dose capsule (1050mg), a low dose capsule (700mg) and a placebo. The study was a “cross-over” design, meaning that participants cycled through the dose active doses and the placebo, taking each for 6 weeks. Each person essentially acted as his or her own “control”, meaning that the study results were more likely to be accurate and meaningful.
The diets of the participants were monitored throughout. "Their calories, carbohydrates, fats and protein intake did not change during the study, nor did their exercise regimen change," study leader Vinson said. On average, the participants were eating around 2400 calories per day.
The subjects lost an average of 17 pounds over the course of the study. This was equal to 10.5% of their overall body weight. Each participant also lost an average of 16% body fat. Telephone interviews conducted 4 months after the study ended found that 14 of the 16 subjects had maintained their weight loss.
The caffeine in the supplement is unlikely to have contributed to the result. In total, the supplements provided up to 20mg caffeine – about the amount in a regular cup of coffee.
The active ingredient in the supplement actually appears to be chlorogenic acid. This is a compound naturally present in green coffee which acts as a strong anti-oxidant, quenching free oxygen radicals.
Chlorogenic acid has been found to slow down the absorption of fat from the intestine and to activate fat metabolism in the liver (2). It also inhibits sugar absorption and influences glucose metabolism (3).
Chlorogenic acid breaks down when coffee beans are roasted, meaning that drinking regular coffee will not offer the same benefits.
The design of the study used only a short break between each ‘cycle’, where the subjects swapped between supplements, and this may have affected the result. Despite this limitation, the authors concluded that the green coffee supplement may be “an effective neutraceutical in reducing weight in preobese adults, and may be an inexpensive means of preventing obesity in overweight adults.”
1. Vinson J, Burnham B, Nagendran MV (2012) 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. 5: 21-27.
2. Shimoda H, Seki E, Aitani M (2006) Inhibitory effect of green coffee bean extract on fat accumulation and body weight gain in mice. BMC Complement Altern Med 17;6:9.