A diet pill that can help women drop a dress size within a matter of weeks could be available within a couple of years.
In a large-scale study, overweight men and women who took lorcaserin for a year lost an average of 8 per cent of their body weight, reports the Daily Mail.
This equates to a stone for a 12st woman - and at least one dress size.
In one or two extreme cases in the 7,000-strong trial, dieters lost up to 40 per cent of their body weight, with most of the pounds melting away in the first few months.
Appetite was cut, waistlines shrunk and cholesterol and blood pressure were lowered, the European Congress on Obesity in Istanbul heard Friday.
However, despite lorcaserin's apparent effectiveness, safety concerns prompted by tests on rats have prevented it from being sold in the U.S.
The drug, taken before breakfast and dinner, affects the way the brain uses serotonin, a chemical that regulates appetite, making those who take it feel less hungry.
Common side-effects in the trial were headaches, dizziness and nausea, but they tended to be temporary.
Crucially, the drug appeared to be free of the cardiac and psychiatric side effects that have caused other obesity pills to be removed from the market in recent years.
Lorcaserin's Californian manufacturer, Arena, now plans to apply for permission to sell the twice-a-day drug in Britain early next year.