ATLANTA – An experimental diet pill helped about half the people who tried it lose some weight and keep it off a year later, without the heart problems that some earlier drugs caused, a study found.

Arena Pharmaceuticals’ lorcaserin is one of three drugs that are boosting hope for a new generation of more effective weight-loss medicines. One gets a Food and Drug Administration review today and the others, later this year.

In the study, lorcaserin caused more people to lose at least 5 percent of their body weight over one year, more than twice the rate achieved by those on dummy pills.

Most people don’t stick to diets. And diet pills have had bad side effects or can’t be taken long-term. A low point came in 1997 when the popular “fen-phen” was pulled from the market after it was tied to heart valve problems.

But now comes lorcaserin, a round blue tablet that would be the first truly novel weight-loss pill in a dozen years if it wins approval.

Results of a large company-funded study of it are in today’s New England Journal of Medicine.

Except for headaches and dizziness, side effects were essentially no worse with the drug than placebo. However, larger studies are needed to conclusively rule out this risk.