A breakthrough drug which directly targets middle-aged spread could help millions of overweight Britons to lose weight.
Slimmers taking the pills lost three times as much weight as those simply trying to diet and exercise, a landmark trial found. The drug also cut the risk of diabetes by a fifth.
Experts hailed lorcaserin as the most effective weight-loss pill yet, suggesting it could help the two in three adults battling weight problems.
The approach could be “the Holy Grail” in the battle to combat obesity, they said.
The US research, which tracked 12,000 obese or overweight adults, found that four in ten of those taking the drug lost a significant amount of weight over the course of a year.
On average, slimmers taking the twice-daily pills lost nine pounds - while those who stuck to traditional diet tips shed just three pounds.
And more than three years after the trial began, they had kept the weight off, the study found.
Scientists said the drug was an “important milestone” after decades of failed attempts to to develop effective diet medication, in a bid to combat the growing global obesity epidemic.
Until now, drugs which showed early promise have had little success - or been dogged by safety concerns, in particular about potential dangers to the heart.
Harvard researchers said their results, presented at the world’s largest cardiac conference, show for the first time that a weight loss drug can cause consistent and sustained weight loss with no such increased risk.
Scientists said the breakthrough was particularly significant, because the drug targets signals in the brain which have been linked to weight gain in middle age.