“Taking multiple capsules of green coffee extract a day, while eating a low fat, healthful diet and exercising regularly, appears to be a safe, effective, inexpensive way to lose weight,” said lead author Joe Vinson.

During the test researchers gave either 700 or 1,050 milligrams of green coffee extract a day or placebo pills to 16 obese adults while carefully observing their diets, physical activity, heart rates, blood pressure and weight.

After 22 weeks participants lost on average 7.9 kilograms and reduced their overall body weight by 10.5 percent, scientists reported at the American Chemical Society’s spring national meeting in San Diego.

Scientists couldn’t definitely explain how the compound helped weight loss but suggested that it may work by reducing the absorption of fat and glucose in the gut and also lowering insulin levels, which would improve metabolic function.

Although coffee bean extract is much less expensive compared to other weight loss compounds, one of its downsides is its extreme bitter taste that makes it difficult to swallow without a lot of water, said Vinson adding that no side effects were seen during the trial.

Nutrimental experts have, however, called for further evidence about the efficacy and safety of the extract, especially in long term. They also want assurances that green coffee extract doesn’t cause malabsorption.

Vinson and his team have planned to conduct a larger trial involving 60 people to get a better understanding of the effects of the extract.