NEW YORK — Willpower apparently can be bought. The chance to win or lose $20 a month enticed dieters in a yearlong study to drop an average of 9 pounds — four times more weight than others who were not offered dough to pass up the doughnuts.
Many employers, insurers, and Internet programs dangle dollars to try to change bad habits like smoking or not exercising, but most studies have found this does not work very well or for very long.
The new study, done with Mayo Clinic employees, was the longest test yet of financial incentives for weight loss. Doctors think it succeeded because it had a mix of carrots and sticks — penalties for not losing weight, multiple ways to earn cash for succeeding, and a chance to recoup lost money if you fell off the ‘‘diet wagon’’ and later repented.
Incentives are ‘‘not like training wheels, where people learn healthy habits and then will continue them on their own, ’’ said one study leader, Dr. Steve Driver. “You have to keep them up for them to work.”
And if you are looking to set up a system like this, the key is to make it self-sustaining, Driver said. The Mayo study did that by having people who did not lose weight put penalties into a fund that paid rewards to those who did. It is also a good idea to make people pony up in advance. One woman flew into a tizzy when she stepped on a scale at a weigh-in and was told she would have to pay.
‘‘She headed for the door, but later came back and paid,’’ Driver said. ‘‘People in Minnesota are pretty honest.’’
The diet study involved 100 obese employees at Mayo Clinic in Minnesota but was not a wellness program. Half were given weight-loss counseling, monthly weigh-ins, and a three-month gym membership. The others had those things, plus financial incentives.
The aim for the group with the incentives was to lose 4 pounds a month up to a goal that depended on their starting weight. If they failed, they paid $20 into a kitty. If they succeeded, they got a voucher to collect $20 when the study ended. Part of the kitty was used to pay the rewards. The rest was put into a lottery that anyone could win, whether they had made their goals or not.
‘‘People saw that if they stuck with it, they had a chance at winning more than they had lost,’’ Driver said.