An experimental weight-loss medication that targets the brain's hunger centre appears to be both safe and effective at helping dieters shed a few pounds, a large company-funded study has found.

The research, appearing in this week's New England Journal of Medicine, found that the drug lorcaserin helped about half the dieters who took it for a year in the study lose a modest amount of weight.

The drug is just one of three new weight-loss medications on the horizon that will soon go before the U.S. Food and Drug Administration for review and approval. All are boosting hopes for those who struggle to battle the bulge and who have disappointed by the current selection of medication options.

The study released Thursday involved more that 3,100 overweight people who were given either placebo pills or the medication, which works on an appetite-controlling serotonin receptor.

After a year, nearly 48 per cent of the lorcaserin group had lost at least five per cent of their body weight -- about 6 kilos (13 lbs) on average. That compares to just 20 per cent in the placebo group who lost the same amount of weight.

Only about half of those in the study stuck with the medications for a full year, a not-altogether-surprising finding, given that diet studies typically have lots of dropouts. But more of the people on lorcaserin stayed in the trial than those on placebo.

A second phase of the study using the participants who remained saw those on dummy pills keep taking them, while those on lorcaserin were assigned either to keep getting it or to switch to dummy pills. Neither they nor their doctors knew which treatment they were receiving.

After another year, 68 per cent of people who continued to take lorcaserin maintained the loss vs. 50 per cent of people switched to placebo.

The most frequently reported side events were headache, dizziness, and nausea, but symptoms tended to resolve after a few weeks.

One side effect noticeably absent was heart trouble. This was good news to researchers, since a previous weight loss medication that targeted serotonin receptors, called fenfluramine, was linked to potentially life-threatening heart valve problems.

Fenfluramine was the "fen" component of the now-notorious "fen-phen" combo treatment. It was taken off the market in 1997.

This study, which was funded by lorcaserin's developer, Arena Pharmaceuticals, found rates of heart valve problems were no higher in the medicated group than in those taking placebo.

As well, lorcaserin did not raise heart rates or blood pressure, as some other weight-loss medications have. In fact, cholesterol levels and other risk factors for heart disease improved in those on the drug.

However, larger studies are needed to confirm those findings.

Currently, the medication options for those struggling with obesity are few.

The appetite suppressant phentermine (the "phen" part of fen-phen) continues to be sold but has been linked to heart palpitations and higher blood pressure.

Sibutramine, another appetite suppressant sold as Meridia, has been tied to heart risks and has been pulled in Europe. And orlistat, a drug that blocks fat absorption and is sold as the prescription drug Xenical or the over-the-counter in the U.S. as Alli, can cause stomach pains and gas.

Another medication that is set for FDA review this week is called Qnexa. It combines two medicines already on the market: phentermine and topiramate, a drug for migraines and epilepsy.

Topiramate has raised safety concerns and carries warnings about possible suicidal tendencies.