A drug developed by Merck could provide a new form of obesity treatment after clinical trials showed it can reduce appetite.
The new weight loss drug, taranabant, was tested on 533 obese patients and was found to bring about significant weight loss at a range of different doses.
People taking 12 milligrams of the drug typically consumed 27 per cent fewer calories than those on a placebo drug and appeared to use up more energy and burn more fat while resting.
Study author Steven Heymsfield, of Merck Research Laboratories, said that the results were surprising.
"We didn't expect weight loss at all doses," he explained.
The drug works by blocking cannabinoid receptors in the brain which are responsible for the psychological effects of cannabis and help to regulate energy balance.
Mr Heymsfield revealed: "The effects of marijuana on appetite have been known for millennia from its medicinal and recreational use.
"When you block the cannabinoid system with an antagonist like taranabant, you suppress appetite."