A weight-loss pill has been hailed the potential "holy grail" in tackling obesity after a study showed it did not increase the risk of serious heart problems.

Researchers say lorcaserin is the first weight-loss drug to be deemed safe for heart health with long-term use.

It could see regulators approve it for prescription on the NHS.

The drug is an appetite suppressant which is taken twice a day.

It works by stimulating brain chemicals to induce a feeling of fullness.


Researchers in the US experimented on 12,000 people who were either obese or overweight.

Some were given the drug and some were given a placebo.

Those who took the drug lost an average of nine pounds - 4kg - in just over three years.

Further analysis showed no big differences in tests for heart valve damage.

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Tam Fry, of the National Obesity Forum, told the Press Association: "I think it is the thing everybody has been looking for.

"I think there will be several holy grails, but this is a holy grail and one which has been certainly at the back of the mind of a lot of specialists for a long time.

"But all of the other things apply - lifestyle change has got to be root and branch part of this."

The Food and Drug Administration, the US medicines watchdog, approved lorcaserin's use in some adults in 2012.

The drug has been on sale there since 2013, where it costs between $220-$290 (£155-£225) a month.

The study into its long-term effects was led by Dr Erin Bohula, a cardiovascular medicine expert at the Harvard-affiliated Brigham and Women's Hospital.

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She said: "Patients and their doctors have been nervous about using drugs to treat obesity and for good reason. There's history of these drugs having serious complications."

As well as heart problems, there are concerns some weight-loss drugs can lead to mental health problems.

Tests for heart valve damage were done on 3,270 participants, but no significant differences in rates were identified.

Suicidal thoughts or behaviour were reported in 21 people taking lorcaserin compared with 11 people given placebo; however, those taking the weight-loss drug had a history of depression.

Dr Aseem Malhotra, a consultant cardiologist with the NHS, questioned the significance of the findings - telling Sky News: "We should be highly sceptical of drug company sponsored trial on a diet pill for weight loss.

"But the results are so marginal, bordering on laughable, that this is clearly not a major part of the solution to solving Britain's obesity epidemic which will come from improving the nation's diet, half of which is now coming from ultra processed food.

"My own patients are not just seeing far better weight and health markers within weeks of cutting out junk but their quality of life improves too, without the risk of side effects from a diet pill."