NEW YORK (Bloomberg) — People who are paid to lose weight shed more than three times as many pounds as those who aren't, according to a study that researchers said may give insurers and employers a tool to make people healthier.

Study participants who were given money as a reward dropped 13 to 14 pounds on average after 16 weeks, compared with a loss of 3.9 pounds by those who didn't get the cash incentive, research in this week's Journal of the American Medical Association showed.

People paid to diet eventually regained some of those pounds during several months once the incentives were stopped, the study said.

About two-thirds of US adults are overweight or obese, and obesity is the second highest cause of preventable premature death in the US behind smoking, the researchers said.

More studies are needed to determine the time period for the incentives before people continue to maintain weight loss on their own, said lead author Kevin Volpp.

Researchers set up three groups in the study. The first group was a lottery-based system in which participants received money if they achieved or exceeded their targets for weight-loss. In the second group, participants deposited their own money into an account that was matched by researchers. The money was lost if they failed to meet their goals.

The third group received no financial incentives, just the monthly weight checkups. All those involved in the study had a goal to lose 16 pounds after 16 weeks.

More than 52 percent of the lottery group lost the 16 pounds, while about 47 percent of the deposit group lost the required weight. In the third group, only 10.5 percent met the 16-pound target loss.